manufacturing system - intro

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Manufacturing SystemsManufacturing Systems


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Manufacturing SystemManufacturing System --

DefinitionDefinition From Latin wordsFrom Latin words ManuManu FactusFactus

DefinitionDefinition

Transformation of materials and information into usefulTransformation of materials and information into usefulproducts (goods)products (goods)

ProductionProduction -- ManufacturingManufacturing

Defining Manufacturing by System TheoryDefining Manufacturing by System TheoryInputInput ProcessProcess Output OutputMaterialsMaterials DesignDesign GoodsGoods

ManpowerManpower Mfg ProcessesMfg ProcessesCapitalCapital Management Management

EnergyEnergy

TechnologyTechnology

DemandDemand SatisfactionSatisfaction


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Types of ProductionTypes of Production

Mass ProductionMass Production Large Quantity (in Millions)Large Quantity (in Millions)

ContinuousContinuous

Specialized MachinerySpecialized Machinery

Low Unit CostLow Unit Cost Assured DemandAssured Demand

High Rate of ProductionHigh Rate of Production

Examples:Examples: Nuts, BoltsNuts, Bolts

Light BulbsLight Bulbs

Batch ProductionBatch Production Small Quantity (Upto thousands)Small Quantity (Upto thousands)

In BatchesIn Batches

General Purpose MachineryGeneral Purpose Machinery

High Unit CostHigh Unit Cost

Made to OrderMade to Order

Low Rate of ProductionLow Rate of Production

Examples:Examples: Large Power GeneratorsLarge Power Generators

AirplanesAirplanes


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Other ClassificationsOther Classifications

ManualManual

MechanizedMechanized

AutomatedAutomated RigidRigid

FlexibleFlexible

LeanLean

CellularCellular


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Main Attributes ofMain Attributes of

Manufacturing SystemManufacturing System

CostCost

TimeTimeQualityQuality

FlexibilityFlexibility


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Cost ElementsCost Elements

Cost of Equipment (Capital Cost)Cost of Equipment (Capital Cost)

Labour CostLabour Cost Material CostMaterial Cost

Energy CostEnergy Cost

Maintenance CostMaintenance Cost Training CostTraining Cost

MiscMisc


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For Capital costFor Capital cost --------------------------

Consider Following ExampleConsider Following Example

CNC LatheCNC Lathe Capital CostCapital Cost Rs 2.5 MilRs 2.5 Mil

Estimated LifeEstimated Life 5 Years5 Years Operation Based on :Operation Based on :

300 days/year300 days/year

16 hours/day16 hours/day

Machine hourly rate:Machine hourly rate:--

2.5x1000,000/5x300x162.5x1000,000/5x300x16

=Rs 1042 per hr=Rs 1042 per hr

Conventional LatheConventional Lathe Capital CostCapital Cost Rs 0.25 MilRs 0.25 Mil

Estimated LifeEstimated Life 5 Years5 Years Operation Based on :Operation Based on :

300 days/year300 days/year

16 hours/day16 hours/day

Machine hourly rate:Machine hourly rate:--

0.25x1000,000/5x300x160.25x1000,000/5x300x16=Rs 104 per hr=Rs 104 per hr


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Work Centre CostWork Centre Cost

It is generally taken as addition ofIt is generally taken as addition of a,b,ca,b,c..

a.a. Capital Cost (Machine Hourly Rate) sayCapital Cost (Machine Hourly Rate) say

370/hr370/hr

b.b. Labour Rate say 120/hrLabour Rate say 120/hr

c.c. O/H say (40% of a) and (55% of b) aboveO/H say (40% of a) and (55% of b) above

Work Centre Cost =Work Centre Cost =370+120+(0.4x370+0.55x120)370+120+(0.4x370+0.55x120)


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Analyzing Cost perAnalyzing Cost perPiece.Piece.

Consider Following ExampleConsider Following ExampleA batch of 150 Part X is machined from 35mm barA batch of 150 Part X is machined from 35mm barstock costing Rs 1800/m. Work centre hourly rate isstock costing Rs 1800/m. Work centre hourly rate is

Rs 705. The machine setup time is 25 hrs, and eachRs 705. The machine setup time is 25 hrs, and eachpart requires 37 min of machining. The job requirespart requires 37 min of machining. The job requiresa single cutting tool costing Rs 610 which lasts for 7a single cutting tool costing Rs 610 which lasts for 7workpieces. Tool change time is 20 min. The cost ofworkpieces. Tool change time is 20 min. The cost ofindirect materials is Rs1184.indirect materials is Rs1184.


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Analyzing Cost per PieceAnalyzing Cost per Piece

Material CostMaterial Cost DirectDirect = 35/1000 x1800= 35/1000 x1800 =Rs63.00/piece=Rs63.00/piece

IndirectIndirect = 1184/150= 1184/150 =Rs7.90/piece=Rs7.90/piece

ToolTool = 610/7= 610/7 =Rs87.14/piece=Rs87.14/piece

Work Centre CostWork Centre Cost SetupSetup = 25/150 x= 25/150 x 705 =Rs117.50/piece705 =Rs117.50/piece

MachiningMachining =37/60x705 = Rs 434.75/piece=37/60x705 = Rs 434.75/piece

Tool Change=20/60x1/7x705=Rs33.57/pieceTool Change=20/60x1/7x705=Rs33.57/piece


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0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00400.00

450.00

500.00

Dir Material Indir

Material

Tool

Material

Set Up Machining Tool

Change

Analyzing Cost per PieceAnalyzing Cost per Piece


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Time!Time!

AvailabilityAvailability

Percentage of the total time thePercentage of the total time theequipment is available for production.equipment is available for production.

ReliabilityReliability

Probability that the equipment willProbability that the equipment willcontinue to remain operational forcontinue to remain operational forcertain specified length of time.certain specified length of time.


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Availability AAvailability A

A = MTBF/(MTBF+MTTR)A = MTBF/(MTBF+MTTR)

MTBFMTBF=Mean Time Between Failures=Mean Time Between Failures

MTTRMTTR=Mean Time to Repair=Mean Time to Repair

5 11 4 7 4 7 35 11 4 7 4 7 3

42 44 87 23 22 21 26 2542 44 87 23 22 21 26 25


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Reliability RReliability R

tt

RR = e= e

WhereWhere = 1/MTBF (Failure= 1/MTBF (FailureRate)Rate)

And t = Mission Time And t = Mission Time


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HereHere = 1/41.43= 1/41.43

= 0.0241= 0.0241

Let us assume 2 shift x 8 hour operationLet us assume 2 shift x 8 hour operationor mission time, thenor mission time, then

-- (0.0241x16)(0.0241x16)

RR = e= e = 0.68 or 68 %= 0.68 or 68 %

Reliability RReliability R


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= .00023 = .00027= .0073= .00025

= .00023+.00025+.0073+.0027

= .00805

Let t=16, Reliability R will be

-

tR = e

= 0.87987 or 87.9 %

Consider Following Example.Consider Following Example.


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= .00023 = .00027= .0073= .00025

= .00023+.00025+.001825 +.00027

= .002575

Let t=16, Reliability R will be

- tR = e

= 0.9596 or 95.96 %

= .0073

= .0073

= .0073

With Redundancy,With Redundancy,Notice the increaseNotice the increase

in Rin R


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QualityQuality

Capability Index (Cp)Capability Index (Cp)Cp = UCLCp = UCL--LCL (say Tolerance) / 6LCL (say Tolerance) / 6

Explanation:Explanation: In this formula, USL and LSLIn this formula, USL and LSLare the upper and lower specification limitsare the upper and lower specification limitsof the quality characteristic of theof the quality characteristic of the productproduct,,respectively. The quantity in therespectively. The quantity in the

denominator, 6denominator, 6 signifies the fact thatsignifies the fact that99.73% of the values generated by the99.73% of the values generated by theprocessprocess is contained within.is contained within.


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Machine Accuracy

Product Tolerance

Cp = 14/6 = 2.33Mfg Process too accurate for the product.


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Product Tolerance

Machine Accuracy

Cp = 2/6 = 0.33 Mfg Process too rough / inaccurate for the product.


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Product Tolerance

Machine Accuracy

Cp = 6.1/6 = 1.02 . The mfg process is well suited for the job.


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Quality :Quality : Consider FollowingConsider Following

Example.Example.

Part Tolerance + 10Part Tolerance + 10 mm

Machine Accuracy (Following random error dataMachine Accuracy (Following random error data

available. All values in m.)available. All values in m.)22 --33 --1 3 1 3 21 3 1 3 2 --2 12 1 --33 --1 01 0

Standard DeviationStandard Deviation ==

Cp = Tolerance/6Cp = Tolerance/6 = == =


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FlexibilityFlexibility

Flexibility of the Mfg System can beFlexibility of the Mfg System can bedefined asdefined as the ease with which thethe ease with which the

production can be changed..production can be changed.. Product, capacity or Process FlexibilityProduct, capacity or Process Flexibility

Product Type can be changedProduct Type can be changed Product flexibilityProduct flexibility

Product Volume can be changedProduct Volume can be changed CapacityCapacity

FlexibilityFlexibility Manufacturing Process can be changedManufacturing Process can be changed ProcessProcessFlexibilityFlexibility

..depending upon how easily..depending upon how easilythese parameters can be altered.these parameters can be altered.


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Penalty of Change (POC) can be calculated for each mfgPenalty of Change (POC) can be calculated for each mfgsystem as followssystem as follows

Product A Product B Product C POCProduct A Product B Product C POC

Sys ISys I 3(.5)3(.5) 2(.3)2(.3) 6(.2)6(.2) 3.33.3

Sys II 5(.5)Sys II 5(.5) 7(.3)7(.3) 1(.2)1(.2) 4.84.8

Sys III 7(.5)Sys III 7(.5) 2(.3)2(.3) 1(.2)1(.2) 4.34.3

Since POC is minimum for Sys I (3.3), it is the most flexible.Since POC is minimum for Sys I (3.3), it is the most flexible.

Flexibility: ExampleFlexibility: Example


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Evolution of Manufacturing Systems in last 50 yearsEvolution of Manufacturing Systems in last 50 years

TimeTimeDurationDuration

DrivingDrivingForceForce

ManufacturingManufacturingStrategyStrategy

SupportSupportSystemsSystems

1960s1960s Cost Cost(Selling)(Selling)

MechanizationMechanization PPC, InvPPC, InvControlControl

1970s1970s Market Market Automation,Automation,DiversificationDiversification

MRPMRP--1, MPS,1, MPS,PUSHPUSH

1980s1980s QualityQuality Process ControlProcess Control MRPMRP--II, PULL,II, PULL,SQCSQC

1990s1990s Time toTime toMarketMarket Responsiveness,Responsiveness,ReengineeringReengineering

CIM, TQMCIM, TQM

2000s2000s Service &Service &ValueValue

Info Sharing, LifeInfo Sharing, LifeCycle, EnvironmentCycle, Environment

Paperless,Paperless,SafetySafety


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The EndThe End

Any Questions?Any Questions?

manufacturing system - intro

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