manufacturing of components for gpm
DESCRIPTION
HMT major projectTRANSCRIPT
A Project report on
Manufacture of Components for General Purpose Machinery
Submitted in the partial fulfillment of the requirements for the award of degree
BACHELOR OF TECHNOLOGY
IN
Mechanical Engineering
Submitted By
Manchikanti Nikhilesh 09D41A0305
Ravirala Venkata Ramana 09D41A0317
Mood Vidish Naik 09D41A0350
Under the Guidance of
Mr.N.V.S.RAMCHANDRA RAO Deputy Manager, Small parts, Hindustan Machine Tools-Praga Division
Department of Mechanical Engineering,
SRI INDU COLLEGE OF ENGINEERING AND TECHNOLOGY
(Affiliated to Jawaharlal Nehru Technological University, Hyderabad)
2012
SRI INDU COLLEGE OF ENGINEERING AND TECHNOLOGY
Department of Mechanical Engineering
CERTIFICATE
This is to certify that the project report titled “Manufacture of components
for General Purpose Machinery” is being submitted by Manchikanti Nikhilesh,
Ravirala Venkata Ramana, Mood Vidish Naik bearing Roll Nos. 09D41A0305,
09D41A0317, 09D41A0350 in IV B.Tech II semester Mechanical Engineering, is a
record bonafide work carried out by them. The results embodied in this report
have not been submitted to any other University for the award of any degree.
Internal Guide:
M.Srinivas Rao << HOD>>
External Guide:
Mr.N.V.S.Ramchandra Rao
ACKNOWLEDGEMENT
The project entitled “MANUFACTURE OF COMPONENTS FOR GENERAL PURPOSE MACHINERY” is the sum of total efforts of our batch. It is our duty to bring forward each and every one who is directly or indirectly in relation with our project and without whom it would not have gained a structure.
We express our grateful thanks to M.SRINIVAS RAO, HEAD OF DEPARTMENT (MECHANICAL ENGINEERING), SRI INDU COLLEGE OF ENGINEERING & TECHNOLOGY for their support in completing our project.
We express our sincere gratitude to Sri N.V.S RAMACHANDRA RAO, Dy. Manager, small parts (production MT-2 shop) for spending his valuable time and suggestions, guidance made by him at various stages of this work done at “HMT MACHINE TOOLS LTD, PRAGA DIVISION”.
DECLARATION
We hereby declare that the whole work done in completing this project is our own effort and we have not copied it from anywhere.
During our project, our project guide Mr. N.V.S.Ramachandra Rao garu guided us to complete our project taking his valuable time. We are very thankful to “HMT MACHINE TOOLS LTD, PRAGA DIVISION” for giving us opportunity to do our project in this esteemed organization.
PROJECT MEMBERSMachikanti Nikhilesh
Ravirala Venkata RamanaMood Vidish Naik
COMPANY PROFILE
“H.M.T Machine Tools PRAGA Division” is one of the leading machine tool
manufacturing units in India. Established in 1943, praga’s products are well known
in the field of machine tools. The company is organized in two divisions – viz the
machine tool and CNC division which pulsates with the activities of employees,
turning out a wide range of products. The two divisions equipped with modern
facilities for design, development and manufacture of machine tools, are manned
by qualified personnel with proven record of technical knowledge and exquisite
craftsmanship acquired over a period of years.
MANUFACTURERS OF Surface Grinding Machines
Cutter & Tool Grinding Machines.
Thread Rolling Machines.
Spline Rolling Machines.
Pulley Forming Machines.
Tube finishing machines.
Milling Machines.
Horizontal Machining Centres.
CNC Lathe Machines.
CNC Milling Machines.
CNC Surface Grinding Machines.
CNC Cutter & Tool Grinding Machines.
Praga are also manufacturers of Customer Tooling for the above Machinery like:
Jigs &fixtures.
Mountings.
Accessories.
Tooling for the above mentioned cold forming processes.
Praga is collaborated with some of the world famous companies like Jones &
Shipman of U.K., Gambin of France, Escoffier of France, George Fischer of
Switzerland, Mitsubishi Heavy Industries Japan and Keiyo Seiki also of Japan. The
collaborations have culminated in Praga producing Machine tools of the highest
quality conforming to international standards.
Praga has contributed to the development of the machine tool industry in the
country and the creation of a vast band of skilled technicians. Thus Praga, today is
a name of reckon with in the Machine Tool Industry.
In compliances of the directives of the Govt. of India actions have been
initiated for the merger of Praga tools limited with HMT limited. Bangalore
obtaining of necessary approvals and sanctions of BIFR and Government of India
with effect from (13-06-2008) and all formalities completed on (20-06-2009).
Praga tools limited renamed as m/s HMT Machine Tools Limited-VI (Praga
division-HYD) from this data all the guidelines and policies, rules and regulations
and facilities are applicable to the Praga employees as per HMT Machine Tools
Limited.
CONTENTSAbstract List of TablesSymbols, Codes& Abbreviations
1. Introduction 1.1 Motivation1.2 Objective of Project1.3 Limitations of Project
2. CLASSIFICATION OF OPERATIONS2.1 Milling
2.1.1 Classification of milling2.1.2 Methods of milling
2.2 Turning2.2.1 Adjustable cutting factors in turning2.2.2 Lathe related operations2.2.3 Cutting tools for lathes2.2.4 Turning machines
2.3 Other
3. MILLING3.1 Motor Flange3.2 Steady Support3.3 Bevel Gear Bracket3.4 Rear Bearing Support
4. TURNING4.1 Spindle Pulley4.2 Front Spindle4.3 Rear Spindle4.4 Front Bearing Cover
5. MILLING, TURNING and OTHER5.1 Coupling5.2 Feed Crank Disc5.3 Worm Wheel5.4 Worm Shaft
6. HEAT TREATMENT6.1 Annealing6.2 Hardening and Tempering6.3 Hardenability6.4 Surface hardening6.5 Carburizing
7. Quality Control Equipment and Inspection
8. CONCLUSION : First Paragraph - Project Conclusion Second Paragraph - Future enhancement
ABSTRACT
Manufacture of components for GPM (General Purpose Machinery) from
raw material stage to finishing stage.
The GPM relates various machines, components such as turning, milling /
machining centers, grinding, gear cutting drilling, die casting & plastic injection
moulding, special purpose machines, refurbishing and retrofitting, special
application components / jigs / fixtures.
Tables:
Drill sizes for tapped hole
Size Pitch DrillsM3 0.5 2.5M4 0.7 3.3M5 0.8 4.2M6 1.0 5.0M8 1.3 6.8
M10 1.5 8.5M12 1.8 10.2M14 2.0 12.0M16 2.0 14.0M18 2.5 15.5M20 2.5 17.5M22 2.5 19.5M24 3.0 21.0
Symbols, Codes and Abbreviations
Ø – Diameter
GPM – General Purpose Machinery
GENERAL CODES OF A CNC MACHINE
0. G00 X---- Y---- Z---- RAPID POSITIONING TO THE
SPECIFIED POINT
1. G01 X---- Y---- F---- LINEAR INTERPOLATION
X= END POINT X - COORDINATE
Y= END POINT Y-COORDINATE
F= FEED IN MM/MIN FOR G94 = FEED IN MM/REV FOR G95
2. G02 X--- Y--- I--- J--- C.W. CIRCULAR INTERPOLATION
X= END POINT X-COORDINATE
Y= END POINT Y-COORDINATE
I= (CENTER POINT – START
POINT) OF X
J= (CENTER POINT –START
POINT) OF Y 3. G03 X--- Y--- I--- J--- C.C.W. CIRCULAR INTERPOLATION
X= END POINT X-COORDINATE
Y= END POINT Y-COORDINATE
I= (CENTER POINT – START
POINT) OF X J= (CENTER POINT –START
POINT) OF Y
3A. G02X----Y----R---- R = CR = CIRCLE or ARC RADIUS
G03 X----Y----R----
G02 X----Y----CR=----
G03 X----Y----CR=----
4. G04 P---- or
G04 F---- or DWELL FOR X or F SECS or P
milliSECS
G04 X----
5. G07 IMAGINARY AXIS DESIGNATION
6. G09 EXACT STOP CHECK
7. G10 SETTABLE WORK OFFSET
8. G16 X----Y---- POLAR COORDINATES ON
(FANUC SYSTEM) X= LENGTH OF LINE
Y= ANGLE +ve IN CCW direction
FROM +X-AXIS
9. G15 POLAR COORDINATES OFF
(FANUC SYSTEM)
10. G110 RP----- AP---- POLAR COORDINATES ON
(SINUMERIK SYSTEM) RP= LENGTH OF LINE or POLAR
RADIUS AP= POLAR ANGLE +ve IN CCW
direction FROM +X AXIS
11. G17 SELECTION OF XY-PLANE
12. G18 SELECTION OF YZ-PLANE
13. G19 SELECTION OF ZX-PLANE
14. G20 INCHES INPUT
15. G21 METRIC INPUT
16. G22 STORED STROKE LIMIT ON
17. G23 STORED STROKE LIMIT OFF
18. G27 REFERENCE POINT RETURN
CHECK
19. G28 RETURN TO REFERENCE POINT
20. G29 RETURN FROM REFERENCE POINT
21. G30 RETURN TO 2nd, 3rd & 4th
REFERENCE POINTS
22. G31 SKIP CUTTING
23. G33 THREAD CUTTING
24. G40 CUTTER COMPENSATION CANCEL
25. G41 CUTTER COMPENSATION LEFT
26. G42 CUTTER COMPENSATION RIGHT
27. G43 TOOL LENGTH COMPENSATION
+ DIRECTION
28. G44 TOOL LENGTH COMPENSATION
- DIRECTION
29. G45 TOOL OFFSET INCREASE
30. G46 TOOL OFFSET DECREASE
31. G47 TOOL OFFSET DOUBLE INCREASE
32. G48 TOOL OFFSET DOUBLE DECREASE
33. G49 TOOL LENGTH COMPENSATION
CANCEL
34. G50 SCALING OFF
35. G51 SCALING ON
36. G54 to G59 WORK COORD. SYSTEMS #1 TO #6
37. G60 SINGLE DIRECTION POSITIONING
38. G61 EXACT STOP CHECK MODE
39. G64 CUTTING MODE
40. G65 CUSTOM MACRO SIMPLE CALL
41. G66 CUSTOM MACRO MODAL CALL
42. G67 CUSTOM MACRO MODAL CALL
CANCEL
43. G68 COORDINATE SYSTEM ROTATION
ON
44. G69 COORDINATE SYSTEM ROTATION
OFF
45. G90 ABSOLUTE PROGRAMMING
46. G91 INCREMENTAL PROGRAMMING
47. G92 PROGRAMMING OF ABSOLUTE ZERO
POINT
48. G94 FEED PER MINUTE
49. G95 FEED PER REVOLUTION
50. G96 CONSTANT SPEED CONTROL ON
51. G97 CONSTANT SPPED CONTROL OFF
58. G98 RETURN TO INITIAL POINT IN A
CANNED CYCLE
59. G99 RETURN TO R-POINT IN A CANNED
CYCLE
60. G80 CANCELLATION OF CANNED CYCLE
61. G73 HIGH SPEED PECK DRILLING
62. G74 LEFT HAND TAPPING
63. G76 PRECISSION BORING CYCLE
64. G81 DRILLING CYCLE
65. G82 DRILLING CYCLE WITH DWELL
66. G83 PECK DRILLING CYCLE
67. G84 RH TAPPING CYCLE
68. G85 BORING CYCLE
69. G86 BORING CYCLE
70. G87 BACK BORING CYCLE
71. G88 BORING CYCLE
72. G89 BORING CYCLE
F CUTTING FEED RATE
R RADIUS OF THE CIRCLE
S SPINDLE SPEED
M-CODES
M00 PROGRAM STOP
M01 OPTIONAL STOP
THIS COMMAND IS ACTIVE ONLY WHEN THE OS-KEY
IS PUT ON
M02 END OF PROGRAM W/O REWIND
M03 SPINDLE CW ROTATION ON
M04 SPINDLE CCW ROTATION ON
M05 SPINDLE ROTATION OFF
M06 TOOL CHANGE
M07 MIST COOLANT ON
M08 FLOOD COOLANT ON
M09 COOLANT OFF
M19 SPINDLE ORIENTATION ON (ORIENTED SPINDLE STOP)
M20 SPINDLE ORIENTATION OFF
M21 TOOL MAGAZINE RIGHT
M22 TOOL MAGAZINE LEFT
M23 TOOL MAGAZINE UP
M24 TOOL MAGAZINE DOWN
M25 TOOL CLAMP
M26 TOOL UNCLAMP
M27 CLUTCH NEUTRAL ON
M28 CLUTCH NEUTRAL OFF
M30 END OF PROGRAM WITH REWIND
M60
M61
M62
M63
M98 CALL OF SUBPROGRAM
M99 END OF SUBPROGRAM
M19 to M28 USED FOR MAITENANCE PURPOSES
1. INTRODUCTION
Classification of components is based upon the types of operation
involved in the manufacturing process.
Manufacturing is defined as a process of making finished goods (as per
requirement) from raw materials. This involves varies mechanical
operations. GPM refers to General Purpose Machinery, the word specifies
to a range of machines that are most commonly used in manufacturing (or
production) in an industry.
1.1 Motivation:
Throughout the centuries, people have challenged to make their lives
easier. One way to accomplish this was to invent tools that make jobs less
difficult. We know these tools as machines. The tools most of us think
about when we hear the word "machine" are actually a combination of two
or more simple machines. We use simple machines every day. We
are dependent on simple machines in many aspects of our lives. You need
a bottle opener to open a soft drink bottle. A carpenter needs a hammer to
separate two boards that have been nailed together incorrectly. A furniture
mover needs to use a ramp to bring up heavy cabinet in to the back of a
truck.
In the same way even for a machine to be manufactured for an industry
there are certain machine manufacture techniques. These can be enhanced
with proper approach in component designs and simplifying the
manufacturing process. This manufacturing process includes to the study of
proper machining operations.
1.2 OBJECTIVE OF PROJECT:
Machines do not increase the work you put into them. The work that
comes out of a machine can never be greater than the work that goes into
it. In reality, the work output is always less than the work input. These
enable various construction companies and organizations to complete their
targeted task in an easy way. These machines help in reducing the manual
labor and also the risk factor, which is usually a constant worry. It becomes
very important to check the latest arrivals in order to meet the industrial
needs. Hence we suppose our project could provide an intimate study
regarding the basic manufacturing technologies and their processes for
those who try to establish an unaccounted growth of their organization.
1.3 LIMITATIONS OF PROJECT:
Even though our project subjects to a brief study on various machining
processes, these operations are restricted only to the specified components
and dimensions, the operational features vary accordingly with the
required component design. However these explain well how the
operational techniques are being adopted in making a component more
flexible for the machinery. Our project is confined only to the components
that are being described here.
2. CLASSIFICATION OF OPERATIONS
Machining is not just one process; it is a group of processes. The
common feature is the use of a cutting tool to form a chip that is removed
from the work part, called swarf. To perform the operation, relative motion
is required between the tool and work. This relative motion is achieved in
most machining operation by means of a primary motion, called "cutting
speed" and a secondary motion called "feed'". The shape of the tool and its
penetration into the work surface, combined with these motions, produce
the desired shape of the resulting work surface.
There are many kinds of machining operations, each of which is capable
of generating a certain part geometry and surface texture.
In turning, a cutting tool with a single cutting edge is used to remove
material from a rotating work piece to generate a cylindrical shape. The
speed motion in turning is provided by the rotating work part, and the feed
motion is achieved by the cutting tool moving slowly in a direction parallel
to the axis of rotation of the work piece.
Drilling is used to create a round hole. It is accomplished by a rotating
tool that is typically has two or four cutting edges. The tool is fed in a
direction parallel to its axis of rotation into the work part to form the round
hole.
In boring, the tool is used to enlarge an already available hole. It is a
fine finishing operation used in the final stages of product manufacture.
In milling, a rotating tool with multiple cutting edges is moved slowly
relative to the material to generate a plane or straight surface. The
direction of the feed motion is perpendicular to the tool's axis of rotation.
The speed motion is provided by the rotating milling cutter.
2.1 MILLING:
Milling is the process of cutting away material by feeding a work piece
past a rotating multiple tooth cutter. The cutting action of the many teeth
around the milling cutter provides a fast method of machining. The
machined surface may be flat, angular, or curved. The surface may also be
milled to any combination of shapes. The machine for holding the work
piece, rotating the cutter, and feeding it is known as the Milling machine.
2.1.1 CLASSIFICATION OF MILLING
Peripheral Milling
In peripheral (or slab) milling, the milled surface is generated by
teeth located on the periphery of the cutter body. The axis of cutter
rotation is generally in a plane parallel to the work piece surface to be
machined.
Face Milling
In face milling, the cutter is mounted on a spindle having an axis of
rotation perpendicular to the work piece surface. The milled surface results
from the action of cutting edges located on the periphery and face of the
cutter.
End Milling
The cutter in end milling generally rotates on an axis vertical to the work
piece. It can be tilted to machine tapered surfaces. Cutting teeth are
located on both the end face of the cutter and the periphery of the cutter
body.
2.1.2 METHODS OF MILLING:
Up Milling
Up milling is also referred to as conventional milling. The direction of the
cutter rotation opposes the feed motion. For example, if the cutter rotates
clockwise, the work piece is fed to the right in up milling.
Down Milling
Down milling is also referred to as climb milling. The direction of cutter
rotation is same as the feed motion. For example, if the cutter rotates
counter clockwise, the work piece is fed to the right in down milling.
The chip formation in down milling is opposite to the chip formation
in up milling. The figure for down milling shows that the cutter tooth is
almost parallel to the top surface of the work piece. The cutter tooth begins
to mill the full chip thickness. Then the chip thickness gradually decreases.
Other milling operations are shown in the figure
2.1.3 Types of Milling MachinesMilling machines can be broadly classified into the following types:
Column and knee type of milling machines
Bed type
Rotary table
Tracer controlled
2.2 TURNING
Turning is the machining operation that produces cylindrical parts. In its
basic form, it can be defined as the machining of an external surface:
With the work piece rotating,
With a single-point cutting tool, and
With the cutting tool feeding parallel to the axis of the work piece
and at a distance that will remove the outer surface of the work.
Taper turning is practically the same, except that the cutter path is at an
angle to the work axis. Similarly, in contour turning, the distance of the
cutter from the work axis is varied to produce the desired shape.
Even though a single-point tool is specified, this does not exclude
multiple-tool setups, which are often employed in turning. In such setups,
each tool operates independently as a single-point cutter.
2.2.1 Adjustable cutting factors in turning
The three primary factors in any basic turning operation are speed,
feed, and depth of cut. Other factors such as kind of material and type of
tool have a large influence, of course, but these three are the ones the
operator can change by adjusting the controls, right at the machine.
Speed, always refers to the spindle and the work piece. When it is
stated in revolutions per minute (rpm) it tells their rotating speed. But the
important figure for a particular turning operation is the surface speed, or
the speed at which the work piece material is moving past the cutting tool.
It is simply the product of the rotating speed times the circumference (in
feet) of the work piece before the cut is started. It is expressed in surface
feet per minute (sfpm), and it refers only to the work piece. Every different
diameter on a work piece will have a different cutting speed, even though
the rotating speed remains the same.
Feed, always refers to the cutting tool, and it is the rate at which the
tool advances along its cutting path. On most power-fed lathes, the feed
rate is directly related to the spindle speed and is expressed in inches (of
tool advance) per revolution (of the spindle), or ipr. The figure, by the way,
is usually much less than an inch and is shown as decimal amount.
Depth of Cut, is practically self explanatory. It is the thickness of the
layer being removed from the work piece or the distance from the uncut
surface of the work to the cut surface, expressed in inches. It is important
to note, though, that the diameter of the work piece is reduced by two
times the depth of cut because this layer is being removed from both sides
of the work.
2.2.2 LATHE RELATED OPERATIONS
The lathe, of course, is the basic turning machine. Apart from
turning, several other operations can also be performed on a lathe.
Boring, Boring always involves the enlarging of an existing hole,
which may have been made by a drill or may be the result of a core in a
casting. Concentricity is an important attribute of bored holes. When boring
is done in a lathe, the work usually is held in a chuck or on a face plate.
Holes may be bored straight, tapered, or to irregular contours. Boring is
essentially internal turning while feeding the tool parallel to the rotation
axis of the work piece.
Facing, Facing is the producing of a flat surface as the result of a
tool's being fed across the end of the rotating work piece. Unless the work
is held on a mandrel, if both ends of the work are to be faced, it must be
turned end for end after the first end is completed and the facing operation
repeated. In the facing of casting or other materials that have a hard
surface, the depth of the first cut should be sufficient to penetrate the hard
material to avoid excessive tool wear.
Parting, Parting is the operation by which one section of a work
piece is severed from the remainder by means of a cutoff tool. Because
cutting tools are quite thin and must have considerable overhang, this
process is less accurate and more difficult. The tool should be set exactly at
the height of the axis of rotation, be kept sharp, have proper clearance
angles, and be fed into the work piece at a proper and uniform feed rate.
Threading, Lathe provided the first method for cutting threads by
machines. There are two basic requirements for thread cutting. An
accurately shaped and properly mounted tool is needed because thread
cutting is a form-cutting operation. The resulting thread profile is
determined by the shape of the tool and its position relative to the work
piece. The second by requirement is that the tool must move longitudinally
in a specific relationship to the rotation of the work piece, because this
determines the lead of the thread. This requirement is met through the use
of the lead screw and the split unit, which provide positive motion of the
carriage relative to the rotation of the spindle.
2.2.3 CUTTING TOOLS FOR LATHES
Tool Geometry, For cutting tools, geometry depends mainly on the
properties of the tool material and the work material. The standard
terminology is shown in the following figure. For single point tools, the
most important angles are the rake angles and the end and side relief angles.
The back rake angle affects the ability of the tool to shear the work
material and form the chip. It can be positive or negative. Positive rake
angles reduce the cutting forces resulting in smaller deflections of the work
piece, tool holder, and machine. If the back rake angle is too large, the
strength of the tool is reduced as well as its capacity to conduct heat. In
machining hard work materials, the back rake angle must be small, even
negative for carbide and diamond tools. The higher the hardness, the smaller
is the back rake angle. For high-speed steels, back rake angle is normally
chosen in the positive range.
Most lathe operations are done with relatively simple, single-point
cutting tools. On right-hand and left-hand turning and facing tools, the
cutting takes place on the side of the tool; therefore the side rake angle is of
primary importance and deep cuts can be made. On the round-nose turning
tools, cutoff tools, finishing tools, and some threading tools, cutting takes
place on or near the end of the tool, and the back rake is therefore of
importance. Such tools are used with relatively light depths of cut. Because
tool materials are expensive, it is desirable to use as little as possible. It is
essential, at the same, that the cutting tool be supported in a strong, rigid
manner to minimize deflection and possible vibration. Consequently, lathe
tools are supported in various types of heavy, forged steel tool holders, as
shown in the figure.
The tool bit should be clamped in the tool holder with minimum overhang.
Otherwise, tool chatter and a poor surface finish may result. In the use of
carbide, ceramic, or coated carbides for mass production work, throwaway
inserts are used; these can be purchased in great variety of shapes,
geometrics (nose radius, tool angle, and groove geometry), and sizes.
2.2.4 TURNING MACHINES
The turning machines are, of course, every kinds of lathes. Lathes
used in manufacturing can be classified as engine, turret, automatics, and
numerical control etc.
They are heavy duty machine tools and have power drive for all tool
movements. They commonly range in size from 12 to 24 inches swing and
from 24 to 48 inches center distance, but swings up to 50 inches and center
distances up to 12 feet are not uncommon. Many engine lathes are
equipped with chip pans and built-in coolant circulating system.
Turret Lathes, In a turret lathe, a longitudinally feed able, hexagon turret
replaces the tailstock. The turret, on which six tools can be mounted, can
be rotated about a vertical axis to bring each tool into operating position,
and the entire unit can be moved longitudinally, either annually or by
power, to provide feed for the tools. When the turret assembly is backed
away from the spindle by means of a capstan wheel, the turret indexes
automatically at the end of its movement thus bringing each of the six tools
into operating position. The square turret on the cross slide can be rotated
manually about a vertical axis to bring each of the four tools into operating
position. On most machines, the turret can be moved transversely, either
manually or by power, by means of the cross slide, and longitudinally
through power or manual operation of the carriage. In most cased, a fixed
tool holder also is added to the back end of the cross slide; this often
carries a parting tool.
Through these basic features of a turret lathe, a number of tools can be set
on the machine and then quickly be brought successively into working
position so that a complete part can be machined without the necessity for
further adjusting, changing tools, or making measurements.
CNC Machines, Nowadays, more and more Computer Numerical
Controlled (CNC) machines are being used in every kinds of manufacturing
processes. In a CNC machine, functions like program storage, tool offset
and tool compensation, program-editing capability, various degree of
computation, and the ability to send and receive data from a variety of
sources, including remote locations can be easily realized through on board
computer. The computer can store multiple-part programs, recalling them
as needed for different parts.
2.3 Other
Other conventional machining operations include shaping, planing,
broaching and sawing. Also, grinding and similar abrasive operations are
often included within the category of machining.
3. MILLING
3.1 Motor Flange
Purpose:
It is obvious that every machine is setup with a motor which provides
the complete rotary motion required. This Motor rests on the current
component Motor Flange.
The dovetail of the motor flange allows the sliding movement
of the motor.
This sliding action lets motor movement to and fro and enables
in tightening of the v-belts.
The step wise operations included in making of the motor flange are:
0. Raw material:
The raw material here is the cast iron moulding as show in the figure
Facing of the flat side on the raw material is to be done. It is done
either on a milling machine or on a turning lathe where the raw material
can be held rigid.
1. On a center lathe:
The raw material is held in individual four jaw chuck such that
the facing operation can be carried. The facing tool used here is the parting
tool.
Further to the center of the face a bore of ø30 is to be made.
This is done using a twist drill of ø28mm and further +1 to 1.5mm using the
boring tool.
A counter bore of ø110H7 is made using the same counter
boring tool for 4mm depth.
2. On a milling center:
After the formation of counter bore on the component the component
is sent for milling operations.
The four sides of the component are milled on a horizontal
milling machine making the component 160mm x 160mm dimensionally (l
& b). Here the job is held in a circular chuck which acts like a support and
sufficient packing is made required for the milling operation. For this
initially one side of the job is milled by making 80mm centre distance from
centre to the side. Further the other sides are milled with reference to the
first side with perpendicularity and squareness.
The job is now remained with milling on the other face of the
component and dovetail making. This is done manually on a horizontal
milling machine or using CNC. Where the tools required will be the mill face
cutter, mill cutter with radius and dovetail cutter.
3. On manual milling machine:
Initially the job is milled on either side of the steps provided
for the flange with a 28mm mill cutter such that it measures 120mm
between the milled portions externally.
The dove tail is formed by an appropriate milling of the job by
passing the dove tail cutter of 28 diameter and 600 dovetail, such that the
dovetail formed exactly cuts 600 dovetail without disturbing the 120mm
distance.
Finally the fillet depth is milled with a side and face mill cutter
of 5mm fillet radius to a depth of 5mm.
4. On a radial drilling machine:
Four holes of ø9 through and counter bore of ø13.5 to a depth
of 8mm from the bottom flat face are to be done at equidistant maintaining
a pitch circle diameter (P.C.D) of 130mm.
The four holes are aligned exactly opposite with each side of
the job.
5. Inspection:
The component is inspected for the pitch circle diameter of ø130 and
dove tails using the quality control equipment.
3.2 STEADY SUPPORT
1st operation: Obtaining the required thickness and width (40.5mm,
53.5mm resp.) of the job from raw material.
Raw material: 60mm thick & 63mm wide, mild steel block.
Width & thickness are obtained on a vertical milling machine (speed
range-20 to 1500 rpm) using a cutter having a diameter of 120mm and
the spindle speed of 270rpm.
First a face is made flat & with reference to it i.e., fixing the flattened
side onto the fixed jaw of the machine, other sides made flat &
perpendicular to the previous flattened side. Thus work piece moves in CW
or CCW direction during the cycle of operations.
The perpendicularity is checked with a tri square.
2nd operation:
Length (200mm) is obtained on a horizontal milling machine. With
base as a reference the face 43.5x53.5 is milled perpendicular to the
reference side.
With this face as the reference further the length 200mm is obtained
by milling on the other side.
3rd operation:
In a vertical milling machine, the taper (1- refer fig.) at the side of the
job is cut at an angle of 600 by tilting the mill cutter in the required angle
(600).
4th operation:
The other stock to be removed (2- refer fig.) on the other part of the
side face is removed (Insert fig.) is obtained.
5th operation:
The 19 holes are drilled through on the front side on a drilling
machine (5mm drill each) & tapped with M6.
The work piece is held on parallel blocks & drilling is done i.e., two
holes of 12mm diameter is made & counter boring of ø20x4mm deep
is done on the top.
Other 3 holes of 5mm drill and tapping is done.
Care should be taken that the parallel blocks do not lie beneath the
holes to be drilled i.e., they should be kept away.
6thoperation:
Heat treatment will be done immediately after the last metal cutting
operation (or) before the 1st grinding process. The required heat treatment
process is explained in Heat treatment processes chapter 6.
3.3 BEVEL GEAR BRACKET
On horizontal milling machine:
For the bottom side. Hold in vice; mill thick 2nd side & keep for
grinding
For the two profile sides of the component which are parallel. Hold in
vice; mill flat on R28mm
For two other sides of 16mmx32mm. Hold in vice; mill width to
16mm height.
Inspect
The milling for 16x32 is carried as:
5. Mark for center
6. Mill length one side to maintain 34mm from bore center
7. Mill length second side to 74mm
Further to carry the drilling operations the component is initially heat treated.
8. Stress relieve
9. Surface grind thickness in batches
10. Surface grind bottom face, second side
On radial drilling machine:
11. Hold in jig the component and drill 2 holes ɸ6.75x27 with M8 drill
12. 2 holes ɸ5.8x8 reamɸ6 M8; drill ɸ6 through
On the same drilling machine tapping operations are done at lower spindle
speed.
13. Clamp on table tap, M8x20deep 2 holes
Again on the drilling machine:
14. Bore ɸ35H7; bore ɸ47H10x30.02; *-0.05 from base chamfer both side
15. Chamfer both sides of the component
On the surface grinding machine:
16. Surface grinds other side to maintain 30.02-0.5
Inspection:
17. Inspection of all the milled sides and the holes is done.
On a die grinding machine:
18. Die grind (it is done on areas where machining is undone)
Final step:
19. Painting
20. Inspection of all the operations including profile.
3.4 REAR BEARING SUPPORT
Raw material- a cast iron block of 150mmx130mmx110mm
On milling machine:
The block is milled all the sides on a vertical milling machine,
obtaining the dimensions as shown in the figure.
The two chamfers each 15x15 at the two regions are made by
inclining the milling cutter.
The back side of the component i.e., opposite to the chamfered side
is to be milled accordingly. This is done by holding the chamfered side on
the bed. The two slots are milled perpendicular to each other, of width
20mm.
On radial drilling machine:
A major drill through of 54mm is made 36mm away from the
chamfered side.
This bore on the right face is extended to a diameter of ø90 for a
depth of 2.8mm. This operation can also be done using a milling tool.
At the left face the bore ø54 is extended to ø62 for a depth of 86mm
with a fillet radius of 3mm provided at the end. Further the ø62 is also
extended to ø96 to a depth of 8mm from the face.
The extended regions here are concentric with the ø54 bore.
The chamfered face and the behind face are drilled accordingly with
the through holes and drills respectively.
On CNC lathe:
The drills of M6 with depth 12mm on right face and 20mm on the left
face are done on horizontal machining center using canned cycles.
A groove of 2.5mm thick and diameterø65.5 is made inside the 62
bore at 40mm away from the left face. This groove is obtained by using a
cutter of 2.5mm thickness and diameter less than ø62.
On milling machine:
The through holes made on the chamfered face are milled to form
the counter bore to the drilled hole using a ø14.5mm side and face mill
cutter to a depth of 28mm from the face.
Inspection:
The component is inspected for all the center distances.
4. TURNING
4.1 SPINDLE PULLEY
0. Raw material – here used is the casting of cast iron alloys as show in
the picture.
1. Facing on the side having the same plane of faces for inner and outer
diameters is done. Using a parting tool, a groove of 3 3/8” major diameter
and 1 3/8” minor diameter is made to a depth 5/8” is made on a turret
lathe.
2. Mark the center on the face using a center drill. A through hole of
diameter 17/32” is made.
3. A taper bore is made using a parting tool maintaining major diameter
0.8” and minor diameter 17/32” for a length 21/16”.
4. Turning of outer diameter maintaining 4” is done.
5. Facing is done on the other side making the width 1 ¾”. Another
facing for the smaller diameter ¼” away from the outer plane is done.
6. The groove with major diameter 3 3/8” and minor diameter 1 ¼” is
turned to a depth of 13/16” from the outer plane.
7. Counter bore of 1” is done to a depth of 5/8”.
8. Threads are turned at 20TPI (threads per inch) on the 1 ¼” diameter
to a length of 7/16”.
9. Further the component is sent for making a crown of 7 ½” at an outer
diameter of 3 ¾” leaving the 1/8” thick portion at the ends. This is obtained
using a plunge cutter of 7 ½” radiuses or by part programming on a CNC
turning center.
10. Inspection: The pulley is inspected for all the dimensions including
taper, crown and counter bores using the quality control equipment.
4.2 FRONT SPINDLE
1. Raw material (fig.) –here is a ms rod of required length and
diameter to be turned.
2. Facing is done on both sides for appropriate length.
3. The job is initially turned to ø48mm.
4. Hold one side in chuck. Then turning is done to ø36 through the
length (185+27=) 212mm.
5. Then turn to ø33.8mm to the length (185-10=) 175mm & provide an
undercut at the step.
6. Then turn the length 27mm to ø25mm
7. Bore of 11mm through is done
8. Remove the work piece and fix it into the chuck holding with the soft
jaws.
9. Now the tapered section of the bore is made to a minor diameter of
ø20.2mm and length 84mm with a major diameter ø23.825.
10. To a length 40mm turning is done to a dia. Ø45.5.
11. On a milling machine key way is made of length 11mm.
12. Further threads M25x1.5P are turned on lathe.
13. Inspection and component stores.
4.3 REAR SPINDLE
0. Raw material
Cylindrical rod of ø50 and length 180mm.
1. Initially on a turning lathe,
Ø50 hold in chuck and turning made of ø30 with h10 tolerance to a
length of 117mm with one face as reference.
Step turning at the end of ø30 to a diameter 20mm is also made for
M20 for a length 15mm.
Groove of 1mm width is made 10mm away from ø50 face (at a length
117mm from reference face) of depth ø27. After the groove the ø30 is
turned to ø28.7 h7.
An undercut provided to ø30 at the ø50 face.
Center is marked to the reference face.
2. The other side ø28.7 is hold in soft jaws.
Facing is done and a length of 170mm is obtained.
Ø50 is turned toø45 along the total length.
Ø25 is turned for a length of 43mm from the end.
Chamfers are provided at the end of diameter turning at each
diameter.
Taper is turned for a major diameter of 25mm and a minor diameter
of 2mm. This taper is obtained by form tool of 300 and linear feed.
3. On key way milling machine:
A key way of length 10mm is made on the M20 diameter.
4. Threads are turned to a length of 13mm on M20x1P.
5. Heat Treatment:
The heat treatment is done for making the spindles hard by the
process hardening of the steels as explained in chapter 6.
6. Inspection
The component is inspected for the various lengths, diameters and
for the taper using quality control equipment.
4.4 FRONT BEARING COVER
1. Raw material
2. The job is turned to a 10mm thick disc and ø165mm by turning and
facing as required.
3. A bore of ø112mm is made through concentric with the outer
diameter
4. A step is obtained of 1mm thick and a diameter of 130mm -0.1-0.15 by
turning.
5. Using an end mill cutter a flat side is obtained 152.5mm away from
the other end.
6. With reference to the center and pitch circle diameter of 150mm, 4
holes each 900 apart are drilled with ø8.5mm drill according to the drawing.
7. To the same holes a counter sink from ø16.2 with 900 angle are
made.
8. The component is sent for grinding.
9. Blackening is done.
10. Inspected for diameters and center distances.
5. MILLING, TURNING & OTHER
5.1 COUPLING
0. Raw material
A pattern with required allowances for coupling is made in the pattern
shop and casting is done from the mould obtained. The material used is
cast iron.
1. 140 held in chuck, Turn 90g6. 140 to 141, Drill 55
The turning operations are carried on a turret lathe in which the tool
post carries the turning tool while the turret carries the necessary drill bits.
The job is set on the individual four jaw chuck holding the part of job
having the higher diameter (say 140+10) by aligning it to the center of
the chuck and the Ø90 is obtained.
Further Ø140+10 are also turned to 141 for certain length. The tool
post is set back.
The center of the Ø90 is marked with a center drill bit held in the
turret. Next at a very low speed of spindle Ø55 is drilled with a drill bit of
Ø55 held in turret head.
2. Ø90g6 held in soft chucks. Ø140±0.3 finished (with low speed and low
depth of cut).
After drilling is done the job is removed from the chuck and the 90 is
held in the chuck with soft jaws and the Ø140+10 is turned to Ø140 along
the total length.
3. 66 width pocket milling + Bottom face of 66 width (pocket)Ø90g6 held in chuck
On a horizontal milling machine job is fixed in a chuck holding 90g6.
Using a side & face milling cutter, the pocket of 66width to a length
measuring 71 from the bottom of the component (Ø90g6 face).
In Horizontal milling machine: for side & face cutter: of cutter =
Bottom face; Side face = width
4. Part is sent to CNC machining centers for 39.72 H7 bore and recesses + profile.
Here the CNC operation is included for making of the profile, making
drills to hold the arms of cross piece and groove for the circlip which is a
locking of the cross piece bearing.
CNC progam:
N10 T1M100 B0 ;M6 ;(T1CENTRE DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H1 ;T2 ;M3 S1000 M7 ;G98 G81 R5.0 Z-6.5 F40 ;M5 M9 ;M100 ;M6 ;
N20 T2 ;M6 ;(T2 DIA 14 DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H2 ;T3 ;M3 S450 M7 ;
G98 G81 R5.0 Z-36.0 F40 ;M5 M9 ;M100 ;
N30 T3 ;M6 ;(T3 DIA 25 U DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H3 ;T4 ;M3 S500 M7 ;G98 G81 R5.0 Z-36.0 F40 ;M5 M9 ;M100 ;
N40 T4 ;M6 ;
(T4 DIA 31 U DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H4 ;T5 ;M3 S500 M7 ;G98 G81 R5.0 Z-36.0 F40 ;M5 M9 ;M100 ;N50 T5 ;M6 ;(T5 DIA 38 U DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H5 ;T6 ;M3 S500 M7 ;G98 G81 R5.0 Z-36.0 F40 ;M5 M9 ;M100 ;
N60 T6 ;M6 ;(T6 DIA 25 END DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H5 ;M3 S450 M7 ; (PROFILE FIRST SIDE)R1=4 ;RAM :R2=R1+10 ;R1=R2 ;G0 X110.0 Y35.0 ;G0 Z5.0 ;G01 Z-R2 F40 ;G0 X87.5 Y-54.0 G42 F30 ;X59.9877 ;G02 X45.7218 Y-43.6353 CR=15 ;G01 X28.5317 Y9.2705 ;G03 X-28.5317 Y-9.2705 CR=30 ;G01 X-45.7218 Y-43.6553 ;G02 X-59.9877 Y-54.0 CR=15 ;G01 X-87.5 Y-54.0 ;G0 Z75.0 ;Z125.0 G40 ;IF R3<34 GO TO 'RAM' ;M5 ;M100 ;M00 ;B180 ;
N70 M6 ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100 G43 H5 ;T1 ;M3 S450 M7 ;(PROFILE SECOND SIDE)R1=4 ;RAM :R2=R1+10 ;R1=R2 ;G0 X110.0 Y35.0 ;G0 Z5.0 ;G01 Z-R2 F40 ;
G0 X87.5 Y-54.0 G42 F30 ;X59.9877 ;G02 X45.7218 Y-43.6353 CR=15 ;G01 X28.5317 Y9.2705 ;G03 X-28.5317 Y-9.2705 CR=30 ;G01 X-45.7218 Y-43.6353 ;G02 X-59.9877 Y-54.0 CR=15 ;G01 X-87.5 Y-54.0 ;G0 Z75.0 ;Z125.0 G40 ;IF R3<34 GO TO 'RAM' ;M5 ;M100 ;
N75 M00 ;
N80 T1 ;M100 B0 ;M6 ;(T1 CENTRE DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H1 ;T2 ;M3 S1000 M7 ;G98 G81 R5.0 Z-6.5 F40 ;M5 M9 ;M100 ;M6 ;
N90 T2 ;M6 ;(T2 DIA 14 DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H2 ;T3 ;M3 S450 M7 ;G98 G81 R5.0 Z-36.0 F40 ;M5 M9 ;M100 ;
N100 T3 ;M6 ;(T3 DIA 25 U DRILL) ;G0 G90 G54 X0.0 Y0.0 ;
G0 Z100 G43 H3 ;T4 ;M3 S500 M7 ;G98 G81 R5.0 Z-36.0 F40 ;M5 M9 ;M100 ;
N110 T4 ;M6 ;(T4 DIA 31 U DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H4 ;T5 ;M3 S500 M7 ;G98 G81 R5.0 Z-36.0 F40 ;M5 M9 ;M100 ;
N120 T5 ;M6 ;(T5 DIA 38 U DRILL) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H5 ;M3 S500 M7 ;G98 G81 R5.0 Z-36.0 F40 ;M5 M9 ;M100 ;
N130 T19 ;M100 ;M6 ;(T19 DIA 39 S.F.BORING BAR) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100 G43 H19 ;M3 S500 ;G98 G81 R5.0 Z-142.0 F12 ;M5 M9 ;M100 ;M6 ;
N140 T20;M6 ;(T20 DIA 39.8 FINE BORING BAR) ;G0 G90 G54 X0.0 Y0.0 ;
G0 Z100.0 G43 H20 ;M3 S500 ;G0 Z5.0 ;G01 Z-34.0 F12 ;Z-100.0 F200 ;Z-142.0 F12 ;M19 ;G0 Z100.0 ;M9 ;N150 T21;
M6 ;(T21 DIA 41.8 RECESS) ;G0 G90 G54 X0.0 Y0.0 ;G0 Z100.0 G43 H21 ;M3 S150 ;G0 Z5.0 ;G01 Z-11.1 F50 ;X3.85 F4 ;G02 I-3.85 ;G01 X0.0 Y0.0 F100 ;
Z-130.75 F200 ;G01 X3.85 F4 ;G02 I-3.85 ;G01 X0.0 Y0.0 F100 ;G0 Z100.0 ;M5 M19 ;M100 ;M6 ;M30 ;
5. Broaching of Internal splines:
The internal splines with ø55 as the internal diameter and ø60 as the
external diameter are broached on a vertical broaching machine with the
necessary tool.
6. Relief milling for inserting cross pieces in assembly:
Relief is made for easy movement of cross piece during the assembly
of cross piece. This is done using a milling cutter of 40 width for a thickness
of 5mm of the material at the 40H7 hole. The tool is a end mill cutter
milling done on horizontal milling machine.
7. Phosphate = Blackening.
This blackening process is explained in Heat treatment.
8. Inspection & Dispatch:
The component is inspected accordingly as reference to the drawing
using quality control equipment and dispatched for assembly.
5.2 FEED CRANK DISC
0. Raw material
Raw material here is a cylindrical rod piece of required length.
1st stage:
For a raw cylinder facing is done on one side.
The required step turning operation is performed.
The center to the component on face is marked.
Chamfer provided at each stage
2nd stage: on lathe
Further the facing on the other side is made by holding the already
turned region in soft jaws. (Ex. If diameter obtained by turning is 40.04 then
the soft chuck is 40.04 exactly)
The turned diameters should be concentric.
Center on the face is marked.
Center drill is used to obtain a small hole of 6.5 deep enhancing the
further drilling operations.
15.87mm (3/5”) drill bit is used and bore is made through
Step turning of the inner depth is made.
3rd stage: Milling
The next operation is milling of the job making a slot to the required
depth on vertical milling machine by fixing the smaller diameter of the job
on the bed.
Using a T-slot milling tool of width 20.06mm (13/16”), the required T-
slot is obtained.
4th stage:
Key way made on a vertical slotting machine.
5th stage:
Drills to the required dimensions are made. The holes to be drilled
are made with reference to the appropriate sides and the bore in the
center.
This is done on CNC vertical machining center(VMC 500) with CNC
coding.
CNC Program:
N10 T1;
G0 G90 G55 X0 Y0 Z100 D1;
M3 S1000 M7 F40;
MSG(“C-DRILL”);
MCALL CYCLE 81(100,0,5,-6.5,6.5);
X0 Y-23.812;
MCALL CYCLE 81( 100,0,5,-23.8,23.8);
X-11.113 Y0;
X28.575 Y0;
MCALL;
M19 M9;
N20 T14;
L90;
G0 G90 G55 X0 Y0 Z100 D1;
M3 S1000 M7 F40;
MSG(“3.3 DRILL”);
MCALL CYCLE 81(100,0,5,-20,-20)
X-11.113 Y0;
X28.575 Y0;
MCALL;
M19 M9;
N30 T7;
L90;
G0 G90 G55 X0 Y0 Z100 D1;
M3 S650 M7 F30;
MSG(“11.1 DRILL”);
MCALL CYCLE 81(100,0,5,-25,25);
X0 Y-23.812;
MCALL;
M19 M9;
M30;
6th stage:
Heat treatment is to be done before the 1st grinding process.
This involves blackening of the component.
7th stage:
Grinding is done as required.
8th stage:
Inspection of the total components diameters, thickness and center
distances.
5.3 WORM WHEEL
1. Raw material( toughened brass)
2. Bore turning is made to obtain the bore of diameter 55mm.
3. Outer diameter of 136mm is turned.
4. Facing is done to obtain the width of 50mm.
5. Step turning is done on either side such that it measures a diameter
of 86mm to a length of 5mm on either side provided with a fillet of 2mm
radius.
6. 2 Key ways are made on a key way slotting machine according to the
dimensions.
7. Using a plunge cut of radius 16.83(having a center at a distance of
80mm from the center of the job) a radial depth is obtained on the outer
diameter.
8. On a gear hobbing machine, the gear teeth are cut as per the
dimensions.
9. Grinding of the inner bore and the teeth are carried on the respective
grinding machines.
10. The component is inspected for the gear teeth and bore dimensions
5.4 WORM SHAFT
Raw material
A rod of 50mm diameter and 415mm length is the raw material here.
On a Lathe:
Facing is done on both ends of the job to obtain a length of 407mm.
Initially turning of the rod for overall length is done to a diameter of
45mm.
Further turning for this component involve various diameters. Hence
it is easily done on a copy lathe where the previously finished job is set in
the lathe and tool moves accordingly copying the dimensions as per the
finished job. The depth at each time is to be manually adjusted until the
required steps are obtained.
On milling machine:
An end of the worm shaft where the diameter is 25mm is flattened
on either side to obtain width of 22mm.
In the heat treatment section, the blackening of the component is
done.
On thread milling machine:
The worm thread is obtained by inclining the tool post to the desired
angle and the tool used is a mill cutter of teeth width equal to width of
worm thread.
Inspection:
The diameters and the thread dimensions are checked.
6. HEAT TREATMENT
Heat treatment is generally applied to steels to impart specific
mechanical properties such as increased strength or toughness or wear
resistance. Heat treatment is also resorted to relieve internal stresses and
to soften hard metals to improve machinability. Heat treatment is
essentially a process of heating the steels to a pre-determined temperature
followed by a controlled cooling at a pre-determined rate to obtain desired
end results. The heat treatment process can be classified into:
1. Recrystallization Annealing which is employed to relieve internal
stresses, reduce the hardness and to increase the ductility of strain
hardened metal. At first, upon an increase in the heating temperature the
elastic distortions of the crystal lattices are eliminated. At higher
temperature new grains for and begins to grow (recrystallization).
2. Full annealing which involves phase recrystallization and is achieved by
heating alloys above the temperature required for phase transformation.
This is followed by slow cooling. Full annealing substantially changes the
physical and mechanical properties and refines a coarse grained structure.
3. Quenching wherein hardening alloys are heated above the phase
transformations temperature and are then rapidly cooled (quenched).
4.Tempering involves the reheating of hardened of hardened steel to a
temperature below that required for phase transformation so as to bring it
nearer to an equilibrium state.
6.1 Annealing
Annealing is the process necessary to obtain softness, improve
machinability, increase or restore ductility and toughness, relieve internal
stresses, reduce structural non-homogeneity and to prepare for
subsequent heat treatment operations.
The Process consists of heating the metal to the required
temperature depending upon the carbon content and other alloying
elements of the steel and then cooling in the furnace at a slow rate. Most
of the cast iron components are annealed at a low temperature before final
machining.
6.2 Hardening and tempering
In this process steel is heated to predetermined temperature and
then quenched in water, oil or molten salt baths. Hardening followed by
tempering is done to improve the mechanical properties of steel.
Tempering consists of reheating the hardened steels to a temperature
below lower critical values followed by cooling at a desired rate.
6.3 Hardenability
It is defined as the capacity to develop a desired degree of hardness
usually measured in terms of depth of penetration. The higher the carbon
content, the harder a steel will be after hardening owing to a martensite
structure.
6.4 Surface hardening
This is a selective heat treatment in which the surface layer of metal
is hardened to a certain depth whilst a relatively soft core is maintained.
The principal purpose of surface hardening is to increase the hardness and
wear resistance of the surface. Surface hardening may be accomplished
with or without changing the chemical composition of the surface.
6.5 Carburizing
This is a process for saturating the surface layer of low carbon steels
with carbon. Several methods are employed for this purpose such as pack
carburizing, gas carburizing and liquid carburizing.
After carburizing, regardless of the process employed, the material is
heat treated to produce a hard surface resistant to wear. The heat
treatment process for carburized parts consists of the following:
a) Normalizing after carburizing at temperatures of 8800-9000 to
improve the core structure of the work which is over heated by
carburizing.
b) Hardening at 750-8500to eliminate the effects of overheating and to
impart a high hardness to the carburized layer and
c) Tempering at 1500 to 1800
7. QUALITY CONTROL EQUIPMENT and INSPECTION
Verniers are used for checking external and internal dimensions that
are controlled within ±0.2mm and above. Gear tooth vernier is used for
checking chordal thickness of bevel gears at major diameter in its taper.
Micrometers are used for checking dimensions of shafts and
__________ controlled within ±0.01 to ±0.05.
Three point bore micrometer is used for checking bores of tolerance
±0.03 to ±0.08.
Bore indicators are used for checking bores of tolerance ±0.001 to
0.025.
Flange micrometers are used for checking accurate dimensions on
stepped faces. Pitch micrometers are used for checking effective diameters
of threads.
Groove micrometers are used for checking groove diameters of
external grooves. For checking groove diameters, we use inside caliper and
an external micrometer.
Height gauges are used for checking parallelisms, run outs,
concentricity and so on. On surface plate we use height master for
comparing the heights or distances of holes, faces etc.
Universal hardness tester is used for checking hardness of work
pieces after we calibrate it by cross checking with a master piece provided
for this purpose.
Surface finish tester is used for checking the surface finish of ground
& tapped surfaces in RA and RMS values after calibrating it on master piece.
Sine bar is used for checking the accuracy of angles of tapered
surfaces.
Centrimeter is used for checking the center distances of two holes
directly.
Profile projector is used for checking the irregular contours of work
pieces by comparing the shadow magnified (by 10, 20, 50, 100 times) with a
shadow graph drawn on transparent sheets by design’s depth.
Universal microscope is used for checking the threads, serration
profiles by comparing them with oculars containing ideal (error free)
profiles duly printed on them.
Plug gauges are used for checking the lower and upper limits of
holes. Similarly we use ring gauges for calibrating bore indicators before we
check work pieces with them.
Pins or rollers are used for checking O.W.M on threads/serrations
Sample mics:
8. CONCLUSION
Every aspect of this project has been interesting throughout.
Concluding a project doesn’t just simply, the project ending without
serving a purpose that it should be. Conclusion includes all the summary
of a project which may have in them - the literature survey, procurement
of raw materials, machinery required for production, production
processes, and time estimation for manufacturing and feasibility studies.
It becomes very important to check the latest arrivals in order to
meet the industrial needs. Hence we suppose our project could provide an
intimate study regarding the basic manufacturing technologies and their
processes for those who try to establish an unaccounted growth of their
organization.
BIBLIOGRAPHY:
Machine tool design handbook – Central machine tool institute,
Banglore
Workshop technology- Raghuwamshi
Metrology and surface engineering – R.K.Jain
References:
http://www.mfg.mtu.edu/marc/primers/turning/turn.html
www.wikipedia.org – The encyclopedia
www.pragatools.org