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HJD INSTITUTE OF TECHNICAL EDUCATION AND RESEARCH, KERA

EXPERIMENT NO. 1

AIM: To study about basic concepts of CIM and scope of CIM.

1.1 INTRODUCTION TO CIM

Computer Integrated Manufacturing (CIM) encompasses the entire range of product development and manufacturing activities with all the functions being carried out with the help of dedicated software packages. The data required for various functions are passed from one application software to another in a seamless manner. For example, the product data is created during design. This data has to be transferred from the modelling software to manufacturing software without any loss of data. CIM uses a common database wherever feasible and communication technologies to integrate design, manufacturing and associated business functions that combine the automated segments of a factory or a manufacturing facility. CIM reduces the human component of manufacturing and thereby relieves the process of its slow, expensive and error-prone component. CIM stands for a holistic and methodological approach to the activities of the manufacturing enterprise in order to achieve vast improvement in its performance.

This methodological approach is applied to all activities from the design of the product to customer support in an integrated way, using various methods, means and techniques in order to achieve production improvement, cost reduction, fulfilment of scheduled delivery dates, quality improvement and total flexibility in the manufacturing system. CIM requires all those associated with a company to involve totally in the process of product development and manufacture. In such a holistic approach, economic, social and human aspects have the same importance as technical aspects.

1.2 SCOPE OF CIM

CIM applies computer and communication technology to completely integrate and automate the following four factory operations:

1.2.1 Product Design: The design department of the company establishes the initial database for production of a proposed product. In a CIM system this is accomplished through activities such as geometric modelling and computer aided design while considering the product requirements and concepts generated by the creativity of the design engineer. Configuration management is an important activity in many designs. Complex designs are usually carried out by several teams working simultaneously, located often in different parts of the world.

1.2.2 Manufacturing Engineering: Manufacturing Engineering is the activity of carrying out the production of the product, involving further enrichment of the database with performance data and information about the production equipment and processes. In CIM,

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this requires activities like CNC programming, simulation and computer aided scheduling of the production activity. This should include on-line dynamic scheduling and control based on the real time performance of the equipment and processes to assure continuous production activity. Often, the need to meet fluctuating market demand requires the manufacturing system flexible and agile.

Fig.1.1 Scope of CIM

1.2.3 Factory Automation Hardware: Factory automation equipment further enriches the database with equipment and process data, resident either in the operator or the equipment to carry out the production process. In CIM system this consists of computer controlled process machinery such as CNC machine tools, flexible manufacturing systems (FMS), Computer controlled robots, material handling systems, computer controlled assembly systems, flexibly automated inspection systems and so on.

1.2.4 Business Functions: In CIM the Computer Aided Business Function considers various activities such as purchase, store, cost planning and control, marketing and sales, packaging, finance and accounts, etc. Thus complete integration of these four functions helps in increase of productivity, plant efficiency, and product quality.

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1.3 CIM WHEEL

The new Manufacturing Enterprise Wheel describes six fundamental elements for competitive manufacturing:

1. The central role of the customer and evolving customer needs. A clear understanding of the marketplace and customer desires is the key to success. Marketing, design, manufacturing, and support must be aligned to meet customer needs. This is the bull's-eye, the hub of the Wheel, the vision and mission of the enterprise. 2. The role of people and teamwork in the organization. Included here are the means of organizing, hiring, training, motivating, measuring, and communicating to ensure teamwork and cooperation. This side of the enterprise is captured in ideas such as self-directed teams, teams of teams, the learning organization, leadership, metrics, rewards, quality circles, and corporate culture. 3. The revolutionary impact of shared knowledge and systems to support people and processes. Included here are both manual and computer tools to aid research, analysis, innovation, documentation, decision-making, and control of every process in the enterprise.

Fig 1.2 CIM Wheel4. Key processes from product definition through manufacturing and customer support. There are three main categories of processes: product/process definition; manufacturing; and customer support. Within these categories 15 key processes complete the product life cycle. 5. Enterprise resources (inputs) and responsibilities (outputs). Resources include capital, people, materials, management, information, technology, and suppliers. Reciprocal responsibilities include employee, investor, and community relations, as well as regulatory, ethical, and environmental obligations. In the new manufacturing enterprise, administrative functions are a thin layer around the periphery. They bring new resources into the enterprise and sustain key processes.

6. The manufacturing infrastructure. While a company may see itself as self-contained, its success depends on customers, competitors, suppliers, and other factors in the environment. The manufacturing infrastructure includes: customers and their needs, suppliers,

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competitors, prospective workers, distributors, natural resources, financial markets, communities, governments, and educational and research institutions.

The basic four islands of automation of CIM are discussed below:1). Computer Aided Design (CAD): The major activities covered under CAD are:

i. Geometric modellingii. Engineering Analysis

iii. Simulationiv. Computer aided drafting and documentation

2). Computer Aided Manufacturing Planning and Control (CAMPC):CAMPC is divided into two main areas:

i. Computer Aided Manufacturing Planning and Control (CAMPC), andii. Computer Aided Manufacturing

CAMPC basically includes:i. Production planning

ii. Computer aided process planning (CAPP)iii. Master schedulingiv. Material requirements planning (MRP I)v. Manufacturing resource planning (MRP II)

vi. Inventory management

3). Computer Aided Manufacturing (CAM)It includes the following activities:

i. Computer Aided Manufacturing by FMSii. Computer Aided Quality Assurance (CAQA)

4). Computer Aided Business Functions (CABF)The CABF includes the following activities:

i. Purchaseii. Stores

iii. Cost planning and controliv. Marketing and salesv. Packaging and forwarding

vi. Finance and accountsvii. Human resources and management

It is important that all the activities and functions in CIM are performed by keeping customer at centre point.

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1.4 ROLE OF MANAGEMENT IN CIM

The CIM is not just a technology but it is a philosophy as well. The basic objective of CIM is the complete integration and automation of all functions of factory including the business functions. However, for the success of CIM, there has to be a greater integration of the human resources and the factory resources. It may require the dismantling of the inter-departmental barriers and greater co-ordination among the different departments.

This is possible only with the active involvement of the top management in integration of the human resources. The strong commitment from the top management helps in creating the atmosphere conductive for the successful implementation of CIM. Bringing the human values into organization would help in developing the CIM with human face.

In addition to above role, the basic six tasks to be performed by the management in implementation of CIM are as follows:

1. Develop a business model for a factory to understand the problems.2. Develop a functional model for the processes, functions and activities.3. Develop an information model for system interfaces, database, information

exchange, etc.4. Develop a network model for communication and networking.5. Develop an organizational model for integrating the various islands of automation

on the existing organization structure, culture and to safeguard against detrimental effects.

6. Develop the implementation plan which takes into account special features of the business and operations.

1.5 IMPACT OF CIM ON PERSONNEL

The computer integrated manufacturing has affected all the company personnel from the lowest rank operator to the CEO of the company. The impact of CIM on the workforce is more than that on the technology itself.Some of the impacts of implementation of CIM on personnel are as follows:

1. Downsizing of Workforce:

Implementation of CIM has reduced the requirement of workforce drastically and hence there is a need of downsizing of the workforce at all levels from bottom to top. The downsizing has hit the people with lesser skills.

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2. Requirement of Change in Skill Sets: The implementation of CIM has created a need for change in skills sets of a people. For example NC machine operators need additional skills in CNC technology. The designers need additional skills in the area of modelling, finite element analysis, simulation, manufacturing, etc.

3. Specialists Need to Generalize and Generalists Need to Specialize

The CIM needs more powerful manpower. It demands that specialists must understand functions outside their areas. The CIM also demands that the general purpose manpower of each department must specialize in their area.

Thus the implementation of CIM expects that specialists need to generalize and generalists need to specialize.

4. Culture change in management: The CIM demands the cultural change in management at all levels: lower, middle and top. This is necessary to bring the change in work culture and compartmentalized behaviour of people. This cultural change must start at the top management level so that they can convince the middle and lower management.

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EXPERIMENT-2

Aim: To study about NC CNC machine tools.

2.1 INTRODUCTION

Numerical Control Machine Tool:

NC machine tools are the machine tools which are controlled by letters, numbers and symbols. The NC machine tool runs a program fed into it; without human operator. The NC program consists of set of instructions or statements for controlling the motion of the drives of machine tool as well as the motion of the cutting tool.

In NC machine tool more than one operation may be automatic. Following are the possible functions:

1. Starting and stopping of M/C tool spindle;2. Controlling spindle speed;3. Controlling feed rate;4. Changing the tools;5. Positioning the tools at desired locations.

Computer Numerically Controlled Machine Tool:

T h e d e s i g n a n d c o n s t r u c t i o n o f C o m p u t e r N u m e r i c a l l y C o n t r o l l e d (CNC) machines differs greatly from that of conventional machine tools. This difference arises from the requirements of higher performance levels.

The CNC machines often employ the various mechatronics elements that have been developed over the years. However, the quality and reliability of these machines depends on the various machine elements and subsystems of the machines.

There are some of the important constituent’s parts and aspects of CNC machines to be considered in their designing, for example Machine structure, Guide ways, Feed drives, Spindle and Spindle bearings etc.

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Fig.2.1 Schematic diagram of CNC M/C tool

The basic design factors involved in the design of machine structure are as follows,1. Static load2. Dynamic load3. Thermal load4. Guide ways5. Feed drive: -

1) Servo motor, 2) Mechanical Transmission System

6. Spindle / spindle bearings: - 1) Hydrodynamic 2) Hydrostatic3) Antifriction

7. Measuring Systems: - 1) Direct 2) Indirect

8. Controls, Software and user interface9. Gauging10. Tool monitoring systems: -

1) Direct 2) Indirect

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2.2 CLASSIFICATION

2.2.1 Classification of NC machine tools:

1. According to control loop feedback system: Open Loop and Closed Loop type

2. According to type of tool motion control:

i. Finite Positioning Control and Continuous Path Control NC machines: The finite positioning type is classified further into two types. They are point to point and straight cut systems.

Fig.2.2 Tool Motion Control

ii. Continuous path control machines are further classified into: a. Two axes contouringb. Two and half Axes contouringc. Three axes contouringd. Multi-axes contouring

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3. According to programming methods: Absolute Programming and Incremental programming

4. According to type of controllers: NC based and CNC based controller systems

2.2.2 Classification of CNC machine tools:

1. Classification based on the motion type:

i. Point-to-Point Systems: It is used in some CNC machines such as drilling, boring and tapping machines, etc. The control equipment for use with them is known as point-to-point control equipment.

ii. Contouring Systems (Continuous Path Systems): It is used in CNC machine tools such as milling machines. The controls required for their control are known as

contouring control. These machines require simultaneous control of axes. 2. Classification based on the control loops:

i. Open Loop Systems: Programmed instructions are fed into the controller through an input device. These instructions are then converted to electrical pulses (signals) by the controller and sent to the servo amplifier to energize the servo motors.

ii. Closed Loop Systems: The closed-loop system has a feedback subsystem to monitor the actual output and correct any discrepancy from the programmed input. These systems use position and velocity feedback.

3. Classification based on the power supply: Mechanical power unit refers to a device which transforms some form of energy to mechanical power which may be used for driving slides, saddles or gantries forming a part of machine tool. The input power may be of electrical, hydraulic or pneumatic.

4. Classification based on no. of axes:i. 2 and 3 axes ii. 4 and 5 axes

2.3 CNC SYSTEM ELEMENTS

Any CNC system consists of following elements:

i. Part programii. Program input device

iii. Machine control unitiv. Drive system

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v. Machine toolvi. Feedback system

i. Part Program:

A part program is series of coded instruction that are required to the movement of the machine tools and the ON/OFF controls of auxiliary functions such as spindle rotation and coolant for producing a part. The basic commands of coded instructions are G-codes, M-codes, T-function, and F-function. Any part program, simple or complicated, is coded from these instructions. A word is the basic building unit of the part program. It always starts with an address followed by a numeric value, e.g.

G01 Linear interpolation mode

X5.0 X-dimension (5.0 in +X direction)

F15.0 Feed rate at 15 inches per minute

The coded instructions are composed of letters, numbers, and symbol and are arranged in the format of functional words and blocks, e.g.

N5 G00 X2.0 Y3.0 S1000 M3

Where N5= sequence number

G00= rapid traverse mode

X2.0= X-coordinate (2.0”)

Y3.0= Y-coordinate (3.0”)

S1000= spindle rate (1000 rpm)

M3= spindle on (Clockwise direction)

There are four methods of generating CNC part programs, namely: manual programming method, computer-assisted programming method, conversational programming method, and CAD/CAM programming method. In the manual programming method, standard G-codes, M-codes, T-function, and F-function are used to create the part program block-by-block. A computer program allows the programmer to pre-define part-geometry, tool-path movements and auxiliary functions, in computer-assisted programming method. Most modern CNC controls provide conversational programming function to allow part-programmers to interact with the control for generating part programs. CAD/CAM programming method mainly consists of three components CAD, CAM, and post processor. CAD creates \part geometry; CAM uses that part geometry to generate tool paths. Finally, the postprocessors convert the tool paths to CNC part programs for particular CNC machine.

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ii. Program Input Device:

The program input device is the mechanism used to enter the part program into the CNC control. The main components of program input devices are:

Punch tape recorder Magnetic tape recorder

Computer via RS-232-C communication

NIC card for network communication

Fig.2.3 Typical program input device.

iii. Machine Control Unit:

The machine control unit (MCU) is the backbone of CNC systems. Following six functions are being done by MCU:

Read coded instructions Decode coded instructions Implement interpolations to generate axis motion commands Feed axis motion commands to amplifier circuits to drive axis mechanisms Receive the feedback signals of position and speed for each drive axis Implement auxiliary control functions such as coolant ON/OFF, spindle ON/OFF,

and tool change.

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iv. Drive System:

Amplifier circuit, drive motors, and ball lead screws are main components of a drive system. Control signals i.e. position and speed of each axis is fed to amplifier circuits from MCU. The control signals are augmented to actuate drive motors that in turn rotate ball lead-screws to position the machine table.

v. Machine Tool:

CNC controls are used to control various types of machine tools. Irrespective of type of machine tool is to be controlled, a machine consists of one or two motion axes (X and/or Y) perpendicular to the work head and one motion axis (Z) parallel to the work head. Some machines are equipped with index tables that allow rotary motions (A, B, or C) around the linear axes (X, Y, or Z).

2.4 FEEDBACK SYSTEM

A feedback system is also referred to as a measuring system. It uses position and speed transducers to continuously monitor the position of the cutting tool at any particular time. The MCU uses the difference between reference signals and feedback signals for correcting position and speed errors.

In most of the NC/CNC machines, there are linear as well as rotary motions. For the position measurements of linear and rotary motions, two types of incremental encoders are used as feedback devices:

2.4.1 Rotary Encoders: It consists of a glass disc with accurately etched lines at equal regular intervals on the outer periphery of the disc. The disc is connected to the lead screw either directly or through precision gearing.

The disc rotates between a light source and a photodiode. The etched lines make or break the photoelectric beam and a pulse signal generated is magnified to give a square wave output.

A rotary encoder with 360 lines can give 360 pulses per revolution, and if a lead screw with 3.6mm pitch is connected to such an encoder, it will give one pulse for every 0.01mm linear movement of slide.

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Fig 2.4 Rotary encoder

2.4.2 Linear Encoder: The linear encoders are connected partly to machine structure or guide and partly to the slides which moves over stationary guide ways.The principle of operation of linear incremental encoder is nearly same as that of the rotary encoder. Here, instead of disc, glass scales with line grating are used, which have line graduations. The relative movement between the glass scale fixed to slides and photoelectric sensing device fixed to guide results in alternate light pulses which generates an electric pulse. The periodic signals are processed and converted into equivalent linear movement.

Fig 2.4 Linear encoder

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EXPERIMENT N0. 3

AIM: To study about manual part programming.

3.1 INTRODUCTION

The part programming is the set of machining instructions, written in standard format, for the NC/CNC machine.These instructions can be either punched on tape using the tape punching machine or directly fed to the machine.

3.2 TYPES OF PROGRAMMING METHODS:

3.2.1 Absolute Co-ordinate System:

In the absolute system the co-ordinates of a point are always referred with reference to the same datum. The datum positions in the X-axis, y-axis and Z-axis are defined by the user/programmer before starting the operation on the machine. The major advantage of using absolute system is that it is very easy to check or correct a programme using this method. If a mistake made in the value of any dimension in a particular block, it may affect that dimension only and once the error is corrected there will be no further problems.

Fig 3.1 Absolute coordinate system

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3.2.2 Incremental Co-ordinate System:

In the incremental system the co-ordinates of any point are calculated with reference to the previous point i.e. the point at which the cutting tool is positioned is taken as datum point for calculating the coordinates of the next point to which movement is to be made.

The difference between absolute system and incremental system can be better appreciated with the help of component shown in Fig. The co-ordinates of points PI, P2, P3 and P4 in absolute and incremental system are given in the table below. In addition, the position of a point may be defined using the polar co-ordinates where the distance of the point from a specified datum point and the angle from a specified datum axis give the coordinates of the points.

Fig 3.2 Incremental coordinate system

3.3 AXIS IDENTIFICATION IN NC/CNC MACHINES

Most of the machines have two or more sideways, disposed at right angles to each other, along which the slides are displaced. Each slide can be fitted with a control system and for the purpose of giving commands to the control system the axis have to be identified. The basis of axis identification is the 3-dimensional Cartesian co-ordinate system and the three axis of movement are identified as X, Y and Z axis. The possible linear and rotary movements of machine slides/work piece are shown in Fig. Rotary movements about X, Y and Z axis are designated as A, B and C respectively. The main axis of movement and the direction of movement along this axis are identified as follows:

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Z-axis: The Z-axis is always the axis of main spindle of the machine. It does not matter whether the spindle carries the work piece or the cutting tool. If there are several spindles on a machine, one spindle is selected as the main spindle and its axis is then considered to be Z-axis On vertical machining centres, the Z-axis is vertical and on horizontal machining centres and turning centres, the Z-axis is horizontal. Z movement (+ Z) is in the direction that increases the distance between the work piece and the tool.

X-axis: The X-axis is always horizontal and is always parallel to work holding surface. If the Z-axis is vertical, as in vertical milling machine, positive X-axis (+X) movement is identified as being to the right, when looking from the spindle towards its supporting column.If Z-axis is also horizontal as in turning centres, positive X-axis motion is to the right, when looking from the spindle towards the workspace.

"Y-axis: The Y-axis is always at right angles to both the X-axis and Z-axis. Positive Y-axis movement (+ Y) is always such as to complete the standard 3-dimensional co-ordinate system.

Rotary axis: The rotary motion about the X, Y and Z-axis are identified by A, B, C respectively. Clockwise rotation is designated positive movement and counter-clockwise rotation as negative movement. Positive rotation is identified looking in + X, + Y and + Z directions respectively.

Fig 3.3 Axis Designation of Milling and Drilling m/c.

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3.4 PART PROGRAMING

The part programming of any CNC system consists of the calculation of a tool path along which the machine operations will be performed and the arrangement of those given and calculated data in standard format, which could be converted to an acceptable form for a particular machine control system.

The necessary data for producing a part is as follows.

A) Information taken directly from a drawing:1. Dimensions: length, width, height, radius, etc.2. Segment shape: linear, circular or parabolic.3. Diameter of hole to be drilled.

B) Date established according to surface quality, required tolerances, type of work piece and cutting tool:1. Feed2. Cutting speeds.3. Turn ON and turn OFF coolant.

C) Data determined by the part programmer:1. Direction of cutting circle clockwise or anti-clockwise2. Tool change.

D) Information depending on the particular CNC system e.g. canned cycles available in CNC systems vary from manufacturer to manufacturer.Part programming is of two types:

1. Manual2. Computer assisted.

In the manual part programming, the data required for machining a part is written in a standard format on a special program sheet. It is then entered in the control system through keyboard or through paper punch/reader.

When it becomes very complicated and time consuming, computer assisted part programming is preferred especially in milling, too many mathematical calculations are required to be performed. This can be efficiently done with computer assisted part Programming.CNC part program for machining of the component as shown in fig on CNC turning centre [facing & boring operation]

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3.4.1 CODES USED IN PART PROGRAMMING:

There are many codes specifying t h e particular area of instructions required to control t h e machine tool. The tool path of the CNC machine is then described in machine codes, which usually take the form-

N-G-X Y-Z-I-J-K-F-S-T-M

WhereN = Sequence numberG = Preparatory functionXYZ = Dimension wordsIJK = Dimension words for arcs and circleF = Feed rateS = Spindle speedT = Tool selectionM = Miscellaneous function

1. "N'' - The sequence number is designated by the address character "N" and three numeric digits. The word indicates the start of a specific sequence of operations. It is the first word for the programming sequence within the block.

2. "G" - The preparatory function is designated by the character "G" and two numeric digits. This word immediately follows the sequence number word. The "G" word prepare the numerical control unit for a specific mode of operation, Many G-functions have been standardized G-functions are listed below.

G00 - Rapid movementG01 - Linear interpolationG02 - Circular interpolation-c/wG03 - Circular interpolation –cc/wG04 - DwellG33 - Thread cuttingG40 -Cutter compensation cancelG41 -Cutter compensation-leftG42 -Cutter compensation-rightG70 -Dimensions in inchesG71 -Dimensions in mmG90 - Absolute Co-ordinates systemG91 - Incremental Co-ordinates systemG92 -Zero presetG94 -Feed rate in mm/min

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G95 -Feed rate in mm/rev

3."XYZ" - These addresses signify axis motions in accordance with the designated axis motions of the machine tool. These addresses could be supplemented by W, A, B AND C etc. if the machine has extra axes of motion.

4 "IJK" These addresses are used when employing circular interpolation to specify the centre of the programmed arc. I, J, and K which are the equivalent to X, Y, and Z but with reference to the start point.

5 "F”: The feed rate for slide displacement is expressed in mm/min and is a three digit number prefixed by the letter "F".

6 "S”- The spindle is expressed in rev. /mm, and is a three digit number prefixed by the letter "S".

7 "T" - The tool function is designated by the letter "T" and a maximum of five numeric digits this word immediately follows the spindle speed word. Tool function code identifies the tool to be used or loaded if at a tool change.

8 "M"-The miscellaneous function is designated by the letter M and two numerical digits. These functions are a family of instructions that cause the starting, stopping or setting of a variety of machine functions. Some M-functions have been standardized by popular usage and others have special significance for individual machines. The common standardized functions are listed below.

M02 -programme stopM03 - Spindle on clockwiseM04 -spindle on counter clockwiseM05 -spindle stopM06 -tool changeM08 -coolant onM09 -coolant offM10 -clampM11 -unclampM60 -work piece change

3.4.2 Programming fundamentals

Machining involves an important aspect of relative movement between cutting tool and work piece. In machine tools this is accomplished by either moving the tool with respect to work piece or vice versa. In order to define relative motion of two objects, reference

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directions are required to be defined. These reference directions depend on type of machine tool and are defined by considering an imaginary coordinate system on the machine tool. A program defining motion of tool / work piece in this coordinate system is known as a part program. Lathe and Milling machines are taken for case study but other machine tools like CNC grinding; CNC hobbing, CNC filament winding machine, etc. can also be dealt with in the same manner.

3.4.3 Zero Points and Reference Points

On each CNC machine, zero points and reference points are defined. The part programme for any component is developed relative to these points.

i. Machine Zero (machine origin): The machine zero point is at the origin of the coordinate measuring system of the machine. The machine zero point is fixed and cannot be shifted. The machine zero point is also called 'Home position'

ii. Work Zero (part origin): Work piece zero or datum may be defined as a point, line or surface on the component drawing to which all the dimensions referenced. For writing the part programme, the programmer should know the relationship between the work piece zero coordinates and machine zero coordinates. In other words, all the coordinate values for slide movements have to be defined with reference to the machine zero. However this complicates the part programmer’s job. To simplify the part programme writing, the CNC machines have the facility of floating zero or zero shifting.

iii. Zero Shifts: The zero shifting facility is available on CNC machines. This facility allows the machine tool zero point to be shifted to any position within the programmable area of the machine.

iv. Program Origin: It is also called home position of the tool. Program origin is point from where the tool starts for its motion while executing a program and returns back at the end of the cycle. This can be any point within the workspace of the tool which is sufficiently away from the part. In case of CNC lathe it is a point where tool change is carried out.

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Example: 1

Part program for job prepared on drilling machine:

N010 G71 G90 G94 EOBN020 M03 F200S1000EOBN030 G00 X10.00 Y10.00 EOBN040 G00 Z 2.00 EOBN050 G01 Z-10.00 EOBN060 G00 Z2.00 EOBN070 G00 X50.00 EOBN080 G01 Z-10.00 EOBN090 G00 Z2.00 EOBN100 G00 Y30.00 EOBN110 G01 Z-10.00 EOBN120 G00 Z20.00 EOBN130 G00 X00 Y00 EOBN140 M02

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Example: 2

Part program for job prepared on Lathe machine:

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Example: 3

Part program for job prepared on milling machine:

Given data

Feed= 65 mm/minuteSpeed= 1000 rpmDepth of Cut= 10 mm

N010 G71 G90 G94 EOBN020 T01 S1000 M03 EOBN010 G00 X-20.00 EOBN015 G00 Z-10.00 EOBN020 G01 G42 X0 Y0 F200 EOBN0025 G01 X80.00 EOBN0030 G03 X95.00 Y15.00 I0.0 J 15.00 EOBN0035 G01 Y50.00 EOBN0040 G01 X15.00 EOBN0045 G01 X0 Y35.00 EOBN0055 G01 X0 Y0 EOBN0060 G40 EOBN0065 G00 X-20.00 Z20.00 EOBN0070 M02 EOB

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EXPERIMENT NO: - 4

AIM: - To Study about automation and group technology.

4.1 INTRODUCTION:

Automation can be defined as the technology used for the application of integrated mechanical, electronic and computer based systems in the operation and control of production system. Automation of production system means:

i. Automation of manufacturing facilities, orii. Automation of manufacturing support system, oriii. Automation of the both facilities and manufacturing support systems.

Automation is not economically feasible in low scale production. However, as the volume of production goes on increasing, automation becomes more and more feasible. Some of the examples of automation of processes in production systems are as follows:

i. NC and CNC machines,ii. Automatic assembly machines,iii. Automated assembly lines,iv. Industrial robots,v. Automated material handling system,vi. Automated storage system,vii. Automated inspection and quality control system,viii. Automated transfer lines,ix. Automated feedback and process control equipment,x. Computer aided production planning and control.

4.1.1 Need of Automation:

i. To increase the productivity,ii. To reduce the cost of production,

iii. To improve product quality,iv. To mitigate the effects of labour shortages,v. To reduce production time,

vi. To avoid high cost of not automating,vii. To have better control over manufacturing activities,

viii. To improve worker safety, andix. To reduce or eliminate routine manual and clerical tasks.

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4.1.2 Types of Automation:

The production of automation systems can be broadly classified as:

i. Fixed (Hard) Automationii. Programmable Automationiii. Flexible (Soft) Automation

Fixed Automation: Fixed automation is an automation system in which the sequence of processing operations is fixed by the production equipment configuration. The fixed automation cannot be changed once it is established and hence, it is inflexible in accommodating the product variety.

The fixed automation is economical when there is continuous high demand for the product at the high volume. The initial cost of the automated equipment can be spread over a very large number of units, thus making the unit cost attractive compared with the equipment without automation.

The fixed automation is suitable for continuous flow type production systems and mass production systems. Examples: bottling plant, packaging plants, transfer lines, etc.

Programmable Automation: Programmable automation is an automation system in which the production equipment is designed with a capability to change the sequence of operations so as to accommodate the different product configurations.

The operation sequence is controlled by a program, which is a set of coded instructions that can be read by the equipment. New programs can be prepared and entered into the equipment to produce the new equipment.

To produce a batch of new products, a new program must be prepared and entered into the equipment. The physical setup of the machine (i.e. tooling, fixtures, machine settings, etc.) must also be changed. This changeover procedure takes time and is called as setup time.

Programmable automation is suitable for batch production systems. Examples: NC machine tools, industrial robots, PLC’s, etc.

Flexible Automation: Flexible automation is an extension of programmable automation, which is capable of producing products of design variations, continuously with little or no time loss for changeovers from one product to the other.

There is no production time loss while reprogramming the program fro new configuration of product. Therefore, the system can produce various combinations of products continuously instead of requiring that they may be made in batches.

The variety of products that can be produced by flexible automation system is less than that can be produced by programmable automation system.

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4.2 GROUP TECHNOLOGY:

A batch production is the most common form of production and constitutes more than 50% of the total manufacturing activity. In addition, there is increasing trend towards achieving a higher level of integration between the design and manufacturing activity of a company.

The above two objectives can be achieved by using a manufacturing philosophy known as Group Technology.

Thus, it is a manufacturing philosophy in which similar parts are identified and groups together as a part family, in order to take the advantage of their similarities in design and manufacturing. In a manufacturing plant, similar parts are arranged into part family, which consists of number of similar parts, possesses similar design and/or manufacturing characteristics.

The production machines are grouped into number of machine cells, where each machine cell specializes in the production of one part family. This group technology philosophy of grouping of production machines into machine cells, where each machine cell specializes in the production of one part family is called as Cellular Manufacturing.

The group technology layout for the batch production is shown below. It results in better and reduced material handling, small in-process inventory, less manufacturing lead time and low cost.

Fig 4.1 Group Technology Layout

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4.3 PART FAMILY:

GT is based on a general principle that many problems are similar and by grouping similar problems, a single solution can be found to a set of problems, thus saving time and effort. The group of similar parts is known as part family and the group of machineries used to process an individual part family is known as machine cell.

4.3.1 Methods of Grouping Parts into Families:

i. Manual Visual Inspectionii. Composite Part Method

iii. Production Flow Analysisiv. Classification and Coding

Visual Inspection: In this method grouping of parts into part families is done by direct looking at the part, considering its shape, size and methods of manufacture. This is least expensive method but least sophisticated and least accurate method.

Composite Part Method: In this method the features of all the parts of the part family are combined into a hypothetical composite part.

For a hypothetical part, the list of all operations is done and a tool-setting is done on a multi tool setup. This list of operations includes all operations required for machining the complete part family. Each part of the part family may not need all the operations of hypothetical composite part.

Production Flow Analysis: The production floe analysis uses manufacturing data to identify part families. This process includes following steps:

i. Data collection: The data such as par number and operation sequence is collected from the manufacturing data contained in the route sheets.

ii. Sorting of operations: The operations are arranged according to similarity.

iii.Preparation of PFA chart: The PFA chart containing the data of part numbers against operation or machine code is prepared.

iv. Data analysis: The data from PFA chart is then analysed and parts requiring similar operations are grouped together as part family.

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Fig 4.2 PFA Chart

Part Classification and Coding: Part classification refers to the grouping of parts on the basis of essential features of the parts, while coding is the process of assigning the cods to the parts.

The symbols represent design attributes of parts or manufacturing features of part families. The variations in codes resulting from the way the symbols are assigned can be grouped into three distinct types of codes. Before coding scheme can be a survey of all components feature must be completed and then code value assign to the feature.

Coding can be used for classification purpose and classification requirements must be considered during the construction of a coding scheme, therefore coding and classification are closely related.

4.3.2 Types of Part Coding:

4.3.2.1 Monocode or hierarchical code:

The structure of monocode is like a tree in which each symbol amplifies the information provided in the previous digit. Large amount of information in a relatively small number of digits can be provided. It is Useful for storage and retrieval of design-related information such as part geometry, material, size, etc.

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It is difficult to developed hierarchical code because of all the branches of hierarchy must be defined.

Fig 4.3 Monocode

4.3.2.2 Polycode or attribute:

The code symbols are independent of each other. Each digit in specific location of the code describes a unique property of the work piece. It is easy to learn and useful in manufacturing situations where the manufacturing process has to be described. The length of a polycode may become excessive because of its unlimited combinational features.

4.3.2.3 Hybrid or mixed code:

It is the mixture of both monocode and polycode systems. Mixed code retains the advantages of both systems. Most coding systems use this code structure.

4.4 OPTIZ CODE:

The optiz coding classification system (optiz – 1970) is probably best knowing coding system. It was developed by H optiz of the “Achem test university” in West Germany,

12345 6789 ABCD

Form code Supplementary code Secondary code

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The code used a mixed code structure; however except for the first digit it resembles a chain structure more closely. The optiz code consists of nine digits which can be extended by adding four more digits. The first nine digits are intended to convey both design and manufacturing data; the general interpretation of the nine digits is indicated in the table.

The first five digits are called “form code” or geometric code, can represent parts of following type: rotational, flat, long and cube. The dimension ratio is also used to classify the geometry. The length to diameter ratio is also used to classify cylindrical part and length to width or length to height ratio is also used to classify non rotary part.

Geometric code use five digit representing

(1) Component class

(2) Basic shape

(3) Rotational surface machining

(4) Plane surface machining and

(5) Auxiliary holes, gear teeth and forming

The next four digits constitute the “supplementary code” It indicated some of the attributes that would be use of manufacturing

(1) The first digit represent major dimension,

(2) Work material type

(3) Raw material shape and

(4) Accuracy required

The extra four digits are referred to as the “secondary code” and are designed by the firm intended to serve it own particular needs.

The optiz code is concise and easy to use. It has been adopted by many companies as their coding system several CAM and CAPP system currently use an optiz based coding system.

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EXPERIMENT NO. 5

AIM: To study about Flexible Manufacturing System

5.1 INTRODUCTION:

Flexible Manufacturing system is a highly automated group technology machine cell, consisting of group of workstations (CNC machines or CNC machining centres), interconnected by an automated material handling and storage system and controlled by a computer system.

Flexible manufacturing systems (FMSs) are the most automated and technologically sophisticated of the machine cell types used to implement cellular manufacturing. An FMS usually has multiple automated stations and is capable of variable routings among stations, while its flexibility allows it to operate as a mixed model system. The FMS concept integrates many of the advanced technologies that we met in previous units, including flexible automation, CNC machines, distributed computer control, and automated material handling and storage. FMS is capable of processing variety of parts. The system setup and processes are programmable and can be programmed as the requirement of a part.

The basic features of FMS systems are:

1. Ability to manufacture variety of products2. less manufacturing lead time3. high quality

Fig 5.1 FMS Features

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5.2 ELEMENTS OF FMS:

1. Work Station: The main element of flexible manufacturing system is work station. The flexible manufacturing system consist of one or more workstation which include: CNC machines, CNC machining centres, CNC presses, CNC forging presses, industrial robots, heating furnace etc. The type of workstations used and their sequences depend upon the part to be manufactured.

2. Material handling and storage: The second major element is material handling and storage system. The material handling system performs the following functions:

i. Sequential or random movement of workpieces between workstations.

ii. Handling and locating the workpieces of different configurations,

iii. Temporary storage of workpieces

iv. Loading and unloading of workpieces.

The storage system performs the functions of storage of raw material and storage of finished parts.

3. Computer control system: The computer control system is brain of flexible manufacturing system. It is interfaced with work station, material handling system and storage system. The computer control system integrates, monitors, and controls the functioning of workstations, material handling system.

4. Human Resources: Human resource is needed to manage the operation of flexible manufacturing system.

The functions performed by operators include:

i. Loading of raw material into the systemii. Unloading of finished parts from the system

iii. Changing and setting of tooliv. Programming and operating the systemv. Maintenance of system

vi. Overall management of system.

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Fig 5.2 FMS Layout

5.3 DIFFERENT TYPES OF LAYOUTS:

FMS can be distinguished by how they perform, as either processing operations or assembly operations. FMS are custom-built so that we may expect to find a wide range of types have been implemented to suit differing projects. Each FMS is customized and unique; however, we can still define a typology for FMS depending on:

(1) The number of machines it contains; or

(2) Whether it is a dedicated or random-order FMS, in terms of the parts it processes.

i. Inline layout: In an inclined layout type FMS, the workstations are arranged in a straight line as in fig. The parts flow only in one direction and that too in a straight line. It is the simplest form of the layout and simplifies the material handling system.

Fig 5.3 Inline Layout

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ii. Rotary layout type: In a rotary layout type FMS, the workstations are arranged in a circular arrangement as in fig. The rotary layout type arrangement is compact and it also simplifies the material handling system.

iii. Loop layout type: In a loop layout type FMS, the workstations are arranged in a loop as in fig. In this layout, the loading and unloading stations are located at one end of the loop.

.

Fig 5.4 Loop Layout

iv. Rectangular layout type: In a rectangular type FMS, the workstations are arranged as in fig. This arrangement is a modification of inline layout. This arrangement is used to return the pallets to the starting position.

Fig 5.5 Rectangular Layout

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v. Ladder layout type: In a ladder layout type FMS, the workstations are arranged in the form of rungs of a ladder as in fig. The rungs increase the possible ways of getting from one machine to next. It reduces the transport time between workstations.

Fig 5.6 Ladder Layout

5.4 AUTOMATED STORAGE AND RETRIEVAL SYSTEM (AS/RS):

Machining centre is an automated manufacturing environment represents high capital cost and every attempt must be made to keep the machines in the cutting cycle. Raw materials, jigs and fixtures, pallets and tools must always be available before actual machining can take place manual method of depositing and retrieving these items from storage areas result in inefficient and inadequate control for automated manufacturing. Depending on the degree of automation an automated storage and retrieval system (AS/RS) may be a fully computer controlled system which is capable of moving material in and out of the storage area without humour intervention. AS/RS when used with an automated material handling system can integrate the material handling and storage system with shipping and receiving, production, and material management and control.

AS/RS used for storage of (typically heavy loads of) finished goods, work-in-process, raw material, and supplies.

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5.4.1 AS/RS DESIGN:

i. Load size and opening size.ii. Number and location of I/O stations.

iii. Number, height, and length of storage aisles.iv. Percentage of dual command operations.v. Applicability of transfer cars.

vi. Randomized or dedicated storage or a combination.vii. S/R machine dwell point.

viii. Throughput requirement.ix. Storage lane depth.x. Amount of I/O queue space.

5.4.2 Basic components of AS/RS:

Fig 5.7 Components of AS/RS

i. Storage and retrieved machine

ii. Pickup/deposit [P/D] station

iii. Storage modules and

iv. Control system

The storage structure is usually in the forms of racks; its prime function is supporting multiple levels of selectable loads. The storage/retrieval [S/R] machines, also called cranes, are used to move loads to and from specific locations on either of the aisle in which the s/r machine travels. The pickup/deposit [P/D] station is used to transfer loads to and from the AS/RS. The storage modules are the containers of the stored material. Examples of storage modules include pallets, steel wire baskets and containers, storage bins and special drawers. Control system software is used to

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integrate the various functions such as receiving, storage and rearrangement picking and shipping. Figure gives the basic configuration of an automated storage and retrieval hardware.

5.4.3 TYPES OF AS/RS:

i. Unit load AS/RS:This is typically a lays automated system design to handle unit loads stored on pallet or other standard containers. The system is computer controlled and the S/R machines area automated and designed to handle the unit load continuers.

ii. Miniload AS/RS:This storage system is uses to handle small loads [individual parts] that are contained in bins or drawers within the storage system .the S/R machine is designed to retrieve the bin and deliver it to a P&D station at the end of the aisle so that the individual items can be withdrawn from the bins. The bin or drawer is then returned to its location in the system. The miniload AS/RS is generally smaller than the unit load AS/RS.

iii. Man on-board AS/RS:In case of miniload system which delivers the entire bin to the end of aisle pick station where as in case of man on board system permits the individual items to be picked directly at their storage location. This offers an opportunity to reduce the transaction time of the system.

iv. Automated item retrieval system:These systems are also designed for retrieval of individual items or small unit loads such as part of product in a however in this system the items are stored in single file lanes rather than in bins or drawers when an item is to be retrieved it is released from its lane on to a conveyer for delivery to the pickup station the supply of items in each lane is annoyed from the rear to maintain first in/first out inventory control.

v. Deep lane AS/RS:The deep lane AS/RS is a high density unit load storage system that is appropriate when large quantities are to be stored but the number it separate types of material is relatively staff loads are picked from one side of the rock system by a special S/R type machine designed for retrieval and another special machine is used on the entry side of the rack system for input of loads.

5.4.4 POTENTIAL BENEFITS ACHIEVED BY AS/RS:

i. Re-education in space required.ii. Free manufacturing space for more production facilities

iii. Reduction in man power requirements.iv. Reduced product damage.v. Increase manufacturing efficiency due to.

vi. Reduced lost labour and reduced lost machine productivity.vii. Reduced light& power required for warehouse.

viii. More accrual inventory control.ix. Better production scheduling ability due to better control of in process material.

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5.4.5 DISADVANTAGES OF AS/RS:

i. AS/RS is designed to perform the dedicated function of storage and retrieval the system can be very difficult to modify.

ii. AS/RS requires high optical investment.

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EXPERIMENT NO:-6

AIM: - To Study about various components of Robots.

6.1 INTRODUCTION:

The robot institute of America defines the robots as,” a reprogrammable, multi-functional manipulator designed to move materials, parts, tools or specialized devices through variable programmed motions for performing a variety of tasks”.

A robot is, thus, an example of programmable automation and is designed to perform highly repetitive operation. Industrial robots of today do not look like humans. Instead, they are machines which operate from a fixed location on the factory floor. Future robots are likely to have more attributes similar to the humans.

The robot technology has established over the period of time. It has taken more than half a century. The first generation of robots are referred as dumb robots. These robots strictly work in a fixed sequence. They do not have any sensors which can take corrective action in case of deviation. The second generation of robots are referred as clever robots. They come with a number of sensors which can take corrective action in case of deviation. They are capable of taking logical decision. The third generation of robots are referred as intelligent robots. They are still in design stage. They can take strategic and importance decision. They are design by using the concept of artificial intelligence.

6.2 BASIC COMPONENTS OF ROBOT

A typical robot, shows in fig. consists of following components:

Fig 6.1 Components of Robot

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1. End Effector:

The end effector is the part that is connected to the last joint (hand) of a manipulator, which generally perform and the required tasks handle the objects. The hand of robot has provisions for connecting the end effector that is specially designed for a purpose. The end effector is either controlled by the robot’s controller or the controller communicates with the end effector’s controlling device such as PLC.

2. Manipulator:

Manipulator is the combination of mechanical linkages, connected by joints to form an open loop kinematic chain. The manipulator is capable of movement in various directions. The joints of the manipulator produce the motion which is either rotary or linear. The manipulator gets the task performed through the end effector, which is connected to the manipulator.

3. Actuators:

The actuators are the drives used to actuate the joints of the manipulators. They produce relative rotary or linear motion between two links of joints. In short, they are the ‘muscles’ of the manipulator. The common type of actuators is: servomotors, stepper motors, pneumatic cylinders, and hydraulic cylinders. The actuators are controlled by controller.

4. Controller:

The controller receives the instructions from the processor of a computer and controls the motion of the actuators. It takes feedback from the sensors.

The controller performs following three functions:

i. It stores the position and sequence date of the manipulator.

ii. It initiates and terminates the motions of the individual components (links) of the

manipulators in the desired sequence and at the specified points.

iii. It permits the robot to be interfaced to the outside world via sensors.

5. Sensors: The sensors are used to collect the information about the status of the manipulator and the end effector. This can be done continuously or at the end of desired motion. The sensor collects the information like: instantaneous position, velocity and acceleration, of various links and joints of manipulator. This information is sent to the controller. Using this information, the controller determines the configuration of the robot and controls the movements of the manipulator.

The information sent by the sensors can be analog, digital or combination of two.

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The sensors used in robots can be divided into two classes:

I. Non-Visual Sensors :

The non-visual sensors include: limit switches, position sensors, velocity sensors, or force and tactile sensors.

II. Visual Sensors :

The visual sensors include: TV cameras, vision system, charge-coupled device (CCD), or charge injection device (CID).

6. Processor:

The processor is the brain of robot, which calculates motion of joints so as to achieve the desired action of robot. It sends signals to the controller and receives the feedback from the controller. The processor is a computer which is dedicated to a single purpose.

7. Software:

There are generally three groups of software that are used in robot:

i. Operating system: for operating the computer.

ii. Robotic software: for operation of the robot.

iii. Application programmes: for operation of peripheral devices.

6.3 TYPES OF ROBOT JOINTS AND DEGREES OF FREEDOM:

Two links of a manipulator of a robot, which are connected together in such a way that their relative motion is completely or successfully constrained, form a kinematic joint.

Generally, two types of joints are used in manipulator:

i. Rotary (Revolute) Joint: The rotary (revolute) joint produces pure rotary

motion. Most of the rotary (revolute) joints are electrically driven, either by

stepper motors or, more commonly by servomotors.

ii. Linear (Prismatic) Joint: The linear (prismatic) joint produced linear or

translatory motion. The linear (prismatic) joint are driven by, hydraulic

cylinders, pneumatic cylinder, or linear electric actuators.

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6.3.1 Degrees of freedom of Robot:

Every joint has one degree of freedom (D.O.F). Hence total DOFs of robot is equal to the number of joints. Many robots have six DOFs: three rotational for orientation in space and three translational for positioning. However, it is possible to have us few as two and as many as eight DOFs. A robot having six degrees of freedom is shown in figure. The six degree of freedoms (DOFs) is as follows:

[1.] Degree of freedom of Arm:

The arm typically has three degrees of freedom.

A. Vertical Traverse: Vertical traverse is the upward or downward movement of the

arm. This movement allows the robot to cover the height during its operation.

B. Radial Traverse: Radial traverse is the in and out movement of the arm along its

axis. This movement allows the robot to cover the area during its operation.

C. Rotational Traverse: Rotational traverse is the rotation of the arm about the

vertical axis. This movement allows the robot to occupy desired angular position

about the vertical axis.

[2.] Degree of freedom of Wrist:

The wrist has three degree of freedom.

D. Wrist Pitch: Wrist pitch is the up and down rotation or pitching of the wrist

about the horizontal axis of the wrist.

E. Wrist Yaw: Wrist yaw is the rotation of the wrist in horizontal plane about the

vertical axis of the wrist.

F. Wrist Roll: Wrist roll is the rotation or rolling motion of the about its

longitudinal axis.

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6.4 TYPE OF ROBOT:

The robots are classified into two categories:

i. Non-servo-controlled robotii. Servo-controlled robot

6.4.1 Non-servo-controlled robot:

In non-controlled robot, the axes of robot remain in non-controlled motion (linear or rotary) from initial point till the end stop.

a) Operation sequence for non-servo controlled robot:b) A program ‘start’ causes the controller/sequencer to send ‘on’ signal to the actuator

of the manipulator.c) This causes the actuator to start, there by initiating the motion of the linkages of the

manipulator.d) The motion of linkages continue till they come in contact with ‘end stop’.e) The limit switches located on ‘end stop’ send the signal to the controller/sequencer,

which send ‘off’ signal to the actuator.f) The controller / sequencer now indexes to the next step and send ‘ON’ signal to the

actuator of other link of the manipulator.g) The process is repeated until all steps in the sequence are executed.

6.4.2 Servo-controlled Robots:

In servo-controlled robots, the axes of robots remain in controlled motion from initial point till the end stop.

Operating sequence for servo-controlled robots:

a) At the beginning, the information regarding the desired motion position is stored in the computer.

b) The desired motion sequence is sent by the computer to the controller.c) The controller sends the signals to the actuators.d) The sensors give feedback to the controller. The actual and desired motion positions

are compared and error signal is formede) The error signal is used by the controller to control the operation of the actuators.f) The error signals are modified continuously.

6.4.2.1 TYPE OF SERVO- CONTROLLED ROBOTS:

i. Point-to-point servo-controlled robots : In point –to-point servo controlled robots, the end effort moves from one point to other point in its work envelop along the straight line. Such robots are normally used in loading-unloading and material handling.

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ii. Continuous path servo-controlled robots : In continuous path servo-controlled robots, the end effectors can be made to move along the predetermined continuous path of desired geometry. Such robots are used for spray painting, arc-welding, polishing, grinding, etc.

6.5 TYPES OF SENSORS

6.5.1 Classification Based On Contact

a. Tactile or contact sensors : Tactile sensors measure the parameters by making the physical contact with the object Tactile or contact sensors are further sub divided into three categories.

Fig 6.2 Types of Sensors

b. Tactile or contact sensors : Tactile sensors measure the parameters by making the physical contact with the object Tactile or contact sensors are further sub divided into three categories.

i. Touch sensors: These sensors indicate and respond to the presence or absence of an object. They provide binary output signal. Limit switches and micro switches are the example of touch sensors.

ii. Force sensors: Force sensors indicate the magnitude of the contact force between the object and the sensors. The example of force sensors are: Piezoelectric sensors, force-sensing resistors etc.

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sensors

tactile or contact sensors

touch sensors force sensorsposition and displacement

sensors

external sensors

non contact sensors

proximity and range sensors

robot vision system

voice synthesizers

internal sensors


iii. Position and displacement sensors: Position and displacement sensors are used to measure the displacement, both rotary and linear. The example of displacement sensors are: potentiometers, encoders, resolvers, etc.

b. Non-Contact Sensors:

Non-contact sensors measure the parameters without contacting the object. Non-contact sensors are further sub-divided into three categories.

i. Proximity and range sensors : Proximity sensors give an indication, when object is closed to the sensors. Range sensors are used to measure the distance between the object and the sensors.

ii. Robot (or machine) vision systems : Robot (or machine) vision system is concerned with the sensing of three dimensional vision data and its interpretation by a computer. Function of robot vision system:

a) Sensing and digitizing image datab) Image processing and analysingc) Application

iii. Voice synthesizers : Voice sensing relies on the techniques of speech recognition to analyse spoken words uttered by a human and compare these words with a set of stored word patterns.

6.5.2 Classification Based On Reference Potion:

i. Internal sensor: Internal sensors are used for measurement of parameters with respect to some reference position itself.

ii. External sensors: External sensors are used for measurement of parameters with respect to some reference position outside the robot structure.

6.6 TYPES OF ACTUATORS:-

Actuators are the devices which people the actual motive force for the manipulator joints of the robots. Based on the types of actuating elements, actuators are classified into four types

i. Mechanical Actuatorsii. Hydraulic Actuators

iii. Pneumatic Actuatorsiv. Electric Actuators

The actuators are the drives used to actuate the joints of the manipulators. They produce relative rotary or linear motion between two links of joints. In short, they are the ‘muscles’ of the manipulator. The common types of actuators are: servomotors, stepper motors, pneumatic cylinders, and hydraulic cylinders. The actuators are controlled by controller.

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Fig 6.3 Types of Actuators

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6.7 ROBOT CONTROLLER:-

The controllers may be placed in a separate cabinet or installed in a manipulator structure itself. The controller receives the instructions from the processor of a computer and controls the motion of the actuators. The input instructions can be given through keyboard or through storage devices such as CD, Floppy disk, Magnetic tapes, etc. It takes feedback from the sensors. The instructions to the controller could be in lower level machine languages or higher level programming language.

6.7.1 Functions of Robot controller:

The controller performs the following three functions:

1. It stores the position and sequence date of the manipulator.2. It initiates and terminates the motion of the individual components (links) of

the manipulator in a desired sequence at the specified point.3. It permits the robot to be interfaced to the outside world via sensors.

6.7.2 Types of Robot controllers:

The robot controllers are of following five types:

i. Simple step sequencer ii. Pneumatic logic system

iii. Electronic sequenceriv. Microcomputerv. Minicomputer

The first three types of controllers are used in less expensive open-loop-control robots, while the last two types of controllers are used in close-loop-control robots.

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EXPERIMENT NO:-7

AIM: - To Study about basic types of robots and its configuration.

7.1 INTRODUCTION The robot institute of America defines the robot as, “a reprogrammable, multi-functional manipulator designed to move materials, parts, tools or specialized devices through variable programmed motions for performing variety of tasks. Robot is thus an example of programmable automation and is design to perform highly repetitive operations.

A robot must possess some intelligence which is normally due to computer algorithms associated with its control and sensing sensors. There are now increasing number of applications of robots such as in nursing and aiding a patient. Micro robots are being designed to do damage control inside human veins. Robot like systems is now employed in heavy earth-moving equipment. It is not possible to put up an exhaustive list of robot applications. One type of robot commonly used in the industry is a robotic manipulator or simply a manipulator or a robotic arm. It is an open or closed kinematic chain of rigid links interconnected by movable joints.

7.2 BASIC CONFIGURATIONS OF ROBOT

7.2.1 Cartesian Configuration Robots:

Fig 7.1 Cartesian configuration

Cartesian configuration robot, shown in above fig. provides 3 linier motions along 3 mutually perpendicular axes: X, Y and Z. However there is no rotary motion. This

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configuration provides rectangular work envelope. Cartesian configuration robots are used for assembly, palletizing and machine tool loading.

7.2.2 Cylindrical Configuration Robots

Fig 7.2 Cylindrical Configuration

Cylindrical configuration robot, shown in above fig. provides 2 linier and 1 rotary motions. This configuration, which provides cylindrical work envelope, has good work area to floor area ratio. Cylindrical configuration robots are used for loading and unloading of machine tools.

7.2.3 Polar (Spherical) Configuration Robots:

Polar configuration provides one linear and two rotary configurations as shown in figure. This configuration provides spherical work envelope.

Polar configurations are used for spot welding and manipulation of heavy loads.

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Fig 7.3 Polar Configuration

7.2.4 Jointed-Arm (Articulated) Configuration Robots:

This type of configuration have robotic arm made of two pieces which are jointed together by turning pair. There are two types jointed arm configuration robots:

i. Revolute Robots

ii. SCARA Robots

7.2.4.1 Revolute Robots:

It provides three rotary motions about three mutually perpendicular axes. It consists of two straight links, corresponding to the human forearm and upper arm, connected by a rotary joint.

This configuration, which provides spherical work envelope, has excellent work area to floor area ratio. The revolute robot, which has highly versatile configuration, is used for diverse tasks like: spray painting, seam assembly, spot welding, assembly, heavy material handling, etc.

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Fig 7.4 Revolute Configuration

7.2.4.2 SACRA (Selective Compliance Assembly Robot Arm):

SCARA robot provides one linear and two rotary motions. This configuration provides cylindrical work envelope. These robots are provided with high speed drive motors.

ARA robot has substantial rigidity in the vertical direction but has compliance in horizontal directions. This makes it suitable for high assembly operations where it is expected to perform the insertion task.

Fig 7.5 SCARA Robot

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7.3METHODS OF ROBOT PROGRAMMING

Robot programming is a set of instructions for:

i. Setting a path of the manipulator in a space,ii. For controlling the movement of the end effector, and

iii. For receiving the signal from the sensors.

There are three basic methods of programming:

1. Mechanical Programming

2. Leadthrough (Teachthrough) Programming

3. Textual Language Programming

7.3.1 Mechanical Programming:

The simple, limited-sequence, low-technology robots are controlled by means of the limit switches & mechanical stops. The limit switches and mechanical stops are used for defining end points of their motion path. The setting of these limit switches and mechanical stops is called as mechanical programming.

The mechanical programming is used in simple pick-and-place robots.

7.3.2 Leadthrough (Teachthrough) Programming:

Leadthrough programming consists of forcing the end effector to move through the desired motion path and recording the motion path into the controller memory.

Methods for Accomplishing Leadthrough Programming:

There are two ways of accomplishing leadthrough programing:

(i) Power leadthrough programming method:

The power leadthrough programming method makes use of control box or a teach pendant. The control box or teach pendant is equipped with a combination of toggle switches, buttons, and dials, to control robot’s movements. The teach pendant is used for driving the manipulator and end effector to each of the desired points in the work envelope and recording these points into the computer memory for subsequent playback.

The power leadthrough programming method is used in point-to-point robots such as: machine loading and unloading robots, material handling robots, spot welding robots, etc.

The power leadthrough programming method, which uses teach pendant, can’t be used for regulating continuous path motions in space.

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The teach pendant operates in either of two modes: teach mode and run mode. The teach mode is used to program the robot, while run mode is used to execute the program.

(ii) Manual leadthroug programming method:

In a manual leadthrough programming method, the programmer physically grasps the robot arm, manually moves it through the desired motion path and records the position at closely spaced number of sampling points.

A teach button is normally located near the wrist of the robot.

The manual leadthrough programming method is used in continuous path robots such as: arc welding robots and spray painting robots.

(iii) Textual Language Programming:

The textual language programming uses robot languages to establish the logic and sequence of work cycle. The computer terminal is used to input the program instruction into the controller, but a teach pendant is also used to define the locations of various points in the work envelope.

The robot languages permit the use of: detailed logic flow, subroutines, calculations, communication with sensor for decision making, etc.

7.4 TEXTUAL ROBOT PROGRAMMING LANGUAGES:

The first textual robot programming language, known as WAVE, was developed in 1973. The subsequent textual robot programming languages are: AL, VAL, AML, MCL, RAIL, HELP, RPL, PAL and ADA.

Robot programming languages can be grouped into three major classes:

i. First Generation Language:

These language uses a combination of teach pendant procedures and command statements for robot programming. They define point locations by teach pendant and sequence of the motions by command statements.

This language possess capabilities similar to the advanced teach pendant methods. VAL is an example of first generation language. Some of the limitations are: inability to perform complex sensors, and limited capacity to communicate with other computers.

ii. Second Generation Language:

This can accomplish complex motions, can perform complex arithmetic computations during program execution and can make use of complex sensors. They have better capacity to communicate with other computers. The commonly available second generation languages are: AML, RAIL, MCL and VAL II.

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iii. Future Generation (World Modeling) Language:

The future generation or world modeling languages can perform the robots without the use teach pendant. The robot possesses a three dimensional geometric model of its work envelope by which it knows the desired points without using the teach pendant. The points of motion path are entered with the help of three dimensional coordinates.

The programming can be completely off-line without interrupting the work of the robot.

7.5 APPLICATION OF ROBOTS IN MANUFACTURING INDUSTRY

The applications of robots in manufacturing industry are broadly classify into five areas:

1. Machine Loading and Unloading

2. Material Handling

3. Processing Operations

4. Assembly

5. Inspection

Machine Loading and Unloading

Fig 7.6 Machine loading and unloading

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Robots are used for loading and unloading of parts in CNC machining centres, flexible manufacturing system, die casting machines, punching press, etc. The use of robots in such machine reduces the part handling time, thereby reducing the cycle time and hence improving the productivity. In machine loading and unloading, a robot should be able to orient the work piece correctly so as to locate it accurately to a machine after picking it from bins or conveyor.

Material Handling

The robots are used for shifting the material or finished parts from machine, conveyor, or feeder to the storage pallets and arranging them in order. Such operation is known as palletizing. The robots are also used for shifting the material from storage pallets to the machine, conveyor, or feeder. Such operation is known as depalletizing.

Processing Operation

The robots are also used for performing the operations on work piece. The robots are equipped with tools mounted on the end effectors. Some of the processing operations performed by the robots are:

i. Spot welding

ii. Arc welding

iii. Spray painting

iv. Machining operation

Assembly

In assembly, two or more components are added to form a new entity. The assembly normally involves following operation:

i. Mechanical fastening,

ii. Soldering and brazing,

iii. Welding,

iv. Press fitting,

v. Adhesive bonding

The assembly involves highly repetitive and boring operations which lead to human fatigue. This may adversely affect the product quality and productivity.

Inspection

Robots are used for inspecting parts or sub-assemblies. The inspection probes mounted on the effectors are used for checking the dimensions. In some cases, the robots separate the rejected parts.

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7.6 APPLICATION OF ROBOTS IN OTHER AREAS

Some of applications of robots in areas other than manufacturing are as follows:

1. Medical and surgical application

Special purpose robots are designed to assist surgeons in operation like: knee joint, replacement, heat surgery, neuro surgery, etc.

2. Mining

In mining, robots are used for: exploration, tunnelling, and material handling.

3. Nuclear power plant

In nuclear power plants, robots are used for the inspection and maintenance of atomic reactors.

4. Space research

Robots are commonly used for space research. Although no human has yet landed and explored the mars, number of robots have already landed and explored to mars. The robots are used as the first entitles to explore any new destination in space.

5. Underwater application

It is impossible for human to explore and recover sunken ships and crashed airplanes in deep oceans. Underwater robots are, now a day, used for such application.

6. Mine clearance

The manual mine clearance operation by the military is highly risky. The robots are successfully and effectively used for detecting and clearing of the mines.

7. Entertainment

Most of the engine movies based on science fiction use the robots of different shapes and sizes.

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EXPERIMENT NO: 8

Aim: To study about Computer Integrated Production Manufacturing System.

8.1 COMPUTER AIDED PROCESS PLANNING (CAPP)

Because of the problems encountered with manual process planning, attempts have been made in recent years to capture the logic, judgment, and experience required for this important function and incorporates them into computer programs. Based on the characteristics of a given part, the program automatically generates the manufacturing operation sequence.

A computer-aided process planning (CAPP) system offers the potential for reducing the routine clerical work of manufacturing engineers. At the same time, it provides the opportunity to generate production routines which arc rational, consistent, and perhaps even optimal.

Two alternative approaches to computer-aided process planning have been developed. These are:

i. Retrieval-type CAPP systems (also called variant systems)ii. Generative CAPP systems

8.1.1 RETRIEVAL-TYPE PROCESS PLANNING SYSTEMS:

Retrieval-type CAPP systems use parts classification and coding system and group technology as a foundation. In this approach, the parts produced in the plant arc grouped into part family, distinguished according lo their manufacturing characteristics.

For each part family a standard process plan prepared and this standard process plan stored in the computer file, and retrieved for new work part which form of parts classification and coding system required to organize the computer files and to permit efficient retrieval of the appropriate process plan for a new work part.

For new parts editing of the existing process plan may be take place if new part is slightly different from the standard, but the machine routing may be same for all parts within part family and the specific operations required at each machine may be different. The complete process plan must document the operations as well as the sequence of machines through which the part must be routed. Because of the alterations that are made in the retrieved process plan, this CAPP system is also called the name "variant process plan system''. In short the variant process planning approach can be realized as a four step process;

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i. Definition of coding scheme.ii. Grouping parts into part families.

iii. Development of a standard process plan.iv. Retrieval and modification of standard process plan.

8.1.2 GENERATIVE PROCESS PLANNING SYSTEMS:

Generative process planning involves the use of the computer lo create an individual process plan from scratch, automatically and without human assistance. A computer would employ a set of algorithms to progress through the various technical and logical decisions toward a final Plan.

For manufacturing Inputs to the system would include comprehensive description in of the work part, use of some form of part code number to summarize the work part data, but it does not involve retrieval of existing standard plans in generative CAPP system. It synthesizes design of the optimum process sequence, based on an analysis of part geometry, material and other factors which would influence in the manufacturing decisions. The generative planning approach has the following advantages.

i. It can generate consistent process plans rapidly.ii. New components can be planned as easily as existent components.

iii. It can potentially be interfaced with an automated manufacturing facility to provide detailed and up-to-date control information.

Successful implementation of this approach requires the following key developments:i. The part to be produced must be clearly and precisely defined in a computer-

readable format (e.g., three-dimensional model and GT code).ii. The captured process-planning knowledge and the part description data must be

incorporated into a unified manufacturing database.

8.1.3 BENEFITS OF CAPP:

Whether it is a retrieval system or a generative system, computer-aided process planning offers a number of potential advantages over manually oriented process planning.

i. Process rationalization.ii. Increased productivity of process planners.

iii. Reduced turnaround time.iv. Incorporation of other application programs.v. It can reduce the skill required of a planner.

vi. It can reduce the process-planning time.vii. It can reduce both process-planning and manufacturing costs.

viii. It can create more consistent plans.ix. It can produce more accurate plans.x. It can increase productivity.

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8.2 MATERIAL REQUIREMENTS PLANNING (MRP I)

Material requirement planning, popularly known as MRP I, is a computerized function or a computational technique which converts the master schedule for the product into a detailed schedule for the procurement of raw materials and vendor manufactured components.

The material requirement planning defines:

i. The required quantities of each raw material;ii. The required quantities of each vendor manufactured components;

iii. The timing of placing orders; andiv. The timing of delivery.

The master scheduling provides the weekly and monthly production plan for a number of products. Each product contains the number of components. The different components are made of the different materials. The manufacturing schedule for the different components is different and so is the material procurement schedule. Therefore, the material requirement planning requires high degree of computation and can be done effectively with the help of computers only.

8.2.1 Factors to be considered in MRP I:

The material requirements planning depend upon the number of factors. Some of them are:

i. Dependent and Independent Demands:The dependent demand means the demand for one item depends upon the other. Therefore, for dependent demand it is necessary to only forecast the market demand for the product and establish the delivery schedule for the product. Based on the delivery schedule for the product, the requirements for the components and the raw materials can be precisely estimated. MRP I is a very effective tool in estimating requirements related to dependent demands.

The independent demand means the demand for one item is independent of the demand for another item. Therefore, for independent demands, as demands are not interrelated, it is necessary to separately forecast the demands.

ii. Lumpy Demand:In some cases of the manufacturing, the demand for the raw material or the item will occur at a continuous constant rate.In some other cases of the manufacturing, the demand for the raw material or the item will occur in large increments rather than at a continuous constant rate. The large increments correspond to contain batch of final product. Such demand in large increments is called as lumpy demand. MRP I is effective tool in planning of the lumpy demand.

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iii. Ordering and Manufacturing Lead Times:There are two types of lead times which should be considered in MRP I:

a) Ordering lead time: An ordering lead time of an item is the time required from the initiation of the purchase requisition to the receipt of the item from vendor.

b) Manufacturing Lead Time: The manufacturing lead time for an item is the time required for the complete manufacturing of the item from the start to the finish.

iv. Items of Common Use:In manufacturing, a single raw material may be used to produce more than one type of component. Again, a single component may be used on more than one final product.MRPI is used as an effective tool in planning the procurement of such commonly used items.

8.2.2 Input Parameters to MRPI:

The MRPI converts the master schedule for the product into a detailed schedule for the procurement of the raw materials and vendor manufactured components.

The MRPI program is given three input parameters for performing its functions as:

i. Master Production Schedule:The master production schedule for the product specifies how many units of each product are to be delivered and when.The format of master production schedule is shown below:

Week No. 1 2 3 4 5 6 7Product M1 20 10 - 15 10 20 -Product M2 - 5 10 10 15 - 10

ii. Bill of Materials:The bill of materials gives the list of parts that make each product. The bill of materials for all products put together gives the bill of material file (BOM).The BOM file and production schedule are fed as input for MRPI.

iii. Inventory Record:It is important to have the current inventory record in material requirements planning.The inventory record file along with the BOM and the master production schedule are fed as input to MRP program to get the output of MRPI.

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8.2.3 Outputs of MRPI:

The material requirement planning generates the following outputs:

i. Reports of planned supply orders:These reports contain the supply orders planned to be released in the future.

ii. Supply orders:These supply orders are to be issued by the purchase departments.

iii. Rescheduling notices:The rescheduling notices indicate the changes in due dates of supply orders which is because of changes in the master schedule.

iv. Cancellation notices:The cancellation notices inform the cancellation of supply orders because of the changes in the master schedule.

v. Inventory status report:The inventory status report gives the detail status of the inventory.

8.3 MANUFACTURING RESOURCE PLANNING (MRPII)

Manufacturing Resource Planning can be defined as the computer based production information system that integrates and coordinates all the major functions of the business to produce the right products at right times.

MRPII integrates and coordinates the following activities:

1. Business Planning2. Production Planning3. Capacity Planning4. Master Production Scheduling5. Resource Requirement Planning6. Material Requirement Planning7. Capacity Requirement Planning8. Production Activity Control

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8.4 COST PLANNING AND CONTROL

The cost planning and control is the computerized function used for determining and controlling the unit of the product.

The objectives of the cost planning and control are:

i. Estimating the expected unit cost of the product.ii. Estimating the actual unit cost of the product.

iii. Estimating and analysing the reasons for the difference between the actual unit cost and expected standard unit cost of the product.

In order to achieve the above three objectives, the cost planning and control function is subdivided into sub functions:

1. Cost Planning2. Cost Control

8.4.1 Cost Planning:

The cost planning is the computerized activity which deals with the estimation of the expected standard unit cost of the product.

The expected standard unit cost of the product is the sum of the material cost machining cost, labour cost and overhead costs.

The standard unit cost are computed using various data files such as: bill of materials, material procurement files, process route sheets, machine rates, labour rates, accounting data for overhead costs, etc.

8.4.2 Cost Control:

The control is the computerized activity which deals with:

i. Estimation of the actual unit cost of the product;ii. Establishing and analysing the reasons for the difference between the actual

unit cost and standard unit cost of the product.

The standard unit cost provides the base with which the actual unit cost of the product can be compared for the measurement of the performance of company.

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