(精品)chap018.ppt

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1、McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.1The McGraw-Hill Companies,Inc.,20062McGraw-Hill/IrwinChapter 18Synchronous Manufacturing and Theory of ConstraintsMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.3Goldratts RulesGoldratts Goal of the

2、 FirmPerformance MeasurementCapacity and Flow issuesSynchronous ManufacturingOBJECTIVES McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.4Goldratts Rules of Production SchedulingDo not balance capacity balance the flowThe level utilization of a non-bottleneck resource is not

3、 determined by its own potential but by some other constraint in the systemUtilization and activation of a resource are not the sameAn hour lost at a bottleneck is an hour lost for the entire systemAn hour saved at a non-bottleneck is a mirage McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,Al

4、l Rights Reserved.5Goldratts Rules of Production Scheduling(Continued)Bottlenecks govern both throughput and inventory in the systemTransfer batch may not and many times should not be equal to the process batchA process batch should be variable both along its route and in timePriorities can be set o

5、nly by examining the systems constraints and lead time is a derivative of the scheduleMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.6Goldratts Theory of Constraints(TOC)Identify the system constraintsDecide how to exploit the system constraintsSubordinate everything else

6、to that decisionElevate the system constraintsIf,in the previous steps,the constraints have been broken,go back to Step 1,but do not let inertia become the system constraintMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.7Goldratts Goal of the FirmThe goal of a firm is to m

7、ake moneyMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.8Performance Measurement:FinancialNet profitan absolute measurement in dollarsReturn on investmenta relative measure based on investmentCash flowa survival measurement McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,

8、Inc.,All Rights Reserved.9Performance Measurement:Operational1.Throughputthe rate at which money is generated by the system through sales2.Inventoryall the money that the system has invested in purchasing things it intends to sell3.Operating expensesall the money that the system spends to turn inven

9、tory into throughput McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.10ProductivityDoes not guarantee profitabilityHas throughput increased?Has inventory decreased?Have operational expenses decreased?McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.

10、11Unbalanced CapacityIn earlier chapters,we discussed balancing assembly linesThe goal was a constant cycle time across all stationsSynchronous manufacturing views constant workstation capacity as a bad decisionMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.12The Statistic

11、s of Dependent EventsRather than balancing capacities,the flow of product through the system should be balanced Process Time(B)Process Time(A)106 8 10 12 14Process Time(B)Process Time(A)106 8 10 12 14(Constant)(Constant)(Variable)(Variable)When one process takes longer than the average,the time can

12、not be made upMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.13Capacity Related TerminologyCapacity is the available time for productionBottleneck is what happens if capacity is less than demand placed on resourceNon-bottleneck is what happens when capacity is greater than

13、 demand placed on resourceCapacity-constrained resource(CCR)is a resource where the capacity is close to demand placed on the resource McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.14Capacity Example Situation 1XYMarketCase AThere is some idle production in this set up.Ho

14、w much?25%in YMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.15Capacity Example Situation 2YXMarketCase BIs there is going to be a build up of unnecessary production in Y?Yes,25%in YMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.16Capacity Exampl

15、e Situation 3XYAssemblyMarketCase CIs there going to be a build up in unnecessary production in Y?Yes,25%in YMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.17Capacity Example Situation 4XYMarketMarketCase DIf we run both X and Y for the same time,will we produce any unneed

16、ed production?Yes,25%in YMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.18Time Components of Production CycleSetup time is the time that a part spends waiting for a resource to be set up to work on this same partProcess time is the time that the part is being processedQueu

17、e time is the time that a part waits for a resource while the resource is busy with something else McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.19Time Components of Production Cycle(Continued)Wait time is the time that a part waits not for a resource but for another part

18、 so that they can be assembled togetherIdle time is the unused time that represents the cycle time less the sum of the setup time,processing time,queue time,and wait timeMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.20Saving TimeBottleneckNonbottleneckWhat are the consequ

19、ences of saving time at each process?Rule:Bottlenecks govern both throughput and inventory in the system.Rule:An hour lost at a bottleneck is an hour lost for the entire system.Rule:An hour saved at a nonbottleneck is a mirage.McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved

20、.21Drum,Buffer,RopeABCDEFBottleneck(Drum)Inventorybuffer(time buffer)Communication(rope)MarketExhibit 18.9McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.22Quality ImplicationsMore tolerant than JIT systemsExcess capacity throughout systemExcept for the bottleneckQuality co

21、ntrol needed before bottleneck McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.23Batch SizesWhat is the batch size?One?Infinity?McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.24Bottlenecks and CCRs:Flow-Control SituationsA bottleneck(1)with no set

22、up required when changing from one product to another(2)with setup times required to change from one product to anotherA capacity constrained resource(CCR)(3)with no setup required to change from one product to another(4)with setup time required when changing from one product to another McGraw-Hill/

23、Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.25Inventory Cost Measurement:Dollar DaysDollar Days is a measurement of the value of inventory and the time it stays within an area McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.26Benefits from Dollar Day Measu

24、rementMarketingDiscourages holding large amounts of finished goods inventory PurchasingDiscourages placing large purchase orders that on the surface appear to take advantage of quantity discounts ManufacturingDiscourage large work in process and producing earlier than needed McGraw-Hill/Irwin 2006 T

25、he McGraw-Hill Companies,Inc.,All Rights Reserved.27Comparing Synchronous Manufacturing to MRPMRP uses backward schedulingSynchronous manufacturing uses forward scheduling McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.28Comparing Synchronous Manufacturing to JITJIT is lim

26、ited to repetitive manufacturingJIT requires a stable production levelJIT does not allow very much flexibility in the products produced McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.29Comparing Synchronous Manufacturing to JIT(Continued)JIT still requires work in process

27、when used with kanban so that there is“something to pull”Vendors need to be located nearby because the system depends on smaller,more frequent deliveries McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.30Relationship with Other Functional AreasAccountings influenceMarketing

28、 and productionMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.31Question BowlWhich of the following are examples of Goldratts Rules of Production Scheduling?a.Balance flow,not capacityb.Utilization and activation are the samec.Nonbottlenecks govern throughputd.All of the a

29、bovee.None of the aboveAnswer:a.Balance flow,not capacity(There are eight other rules.)McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.32Question BowlWhich of the following are examples of Goldratts Theory of Constraints?a.Identify the system constraintsb.Decide how to expl

30、oit the system constraintsc.Elevate the system constraintsd.All of the abovee.None of the aboveAnswer:d.All of the aboveMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.33Question BowlWhich of the following is Goldratts“Goal of the Firm”?a.Reduce costsb.Increase jobsc.Increa

31、se market shared.All of the abovee.None of the aboveAnswer:e.None of the above(The Goal of the Firm is to“make money”.)McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.34Question BowlWhich of the following are Goldratts Financial Measurements used to measure a firms ability

32、to make money?a.Net profitb.Return on investmentc.Cash flowd.All of the abovee.None of the aboveAnswer:d.All of the above McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.35Question BowlWhich of the following are Goldratts Operational Measurements used to measure a firms abi

33、lity to make money?a.Throughputb.Inventoryc.Operating expensesd.All of the abovee.None of the aboveAnswer:d.All of the above McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.36Question BowlAccording to Goldratt,any resource whose capacity is less than the demand placed on it

34、,is considered which of the following?a.Nonbottleneck resourceb.Bottleneck resourcec.Capacity-constrained resourced.A buffer resourcee.None of the aboveAnswer:b.Bottleneck resourceMcGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.37Question BowlWhich of the following kinds of

35、 time make up a“cycle time”?a.Setup b.Processingc.Queued.Waite.All of the aboveAnswer:e.All of the above(The correct answer can also include Idle Time.)McGraw-Hill/Irwin 2006 The McGraw-Hill Companies,Inc.,All Rights Reserved.38Question BowlWhen comparing JIT to synchronous manufacturing,synchronous

36、 manufacturing has which of the following drawbacks?a.Limited to repetitive manufacturingb.Requires stable production levelc.Does not allow much flexibility in the products producedd.All of the abovee.None of the aboveAnswer:e.None of the above(These are drawbacks of JIT,not synchronous manufacturing.)The McGraw-Hill Companies,Inc.,200639McGraw-Hill/IrwinEnd of Chapter 18