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1、Chapter 10Lean ManagementChapter SummaryThis chapter covers the history, philosophy, benefits, problems, and applications of lean production and just-in-time. It also covers in great detail the difference between traditional systems and lean thinking in terms of engineering, capacity, transformation
2、 system, layout, workforce, inventories, scheduling, and so on.Discussion Outline1. Lean Philosophy & HistoryPhilosophyElimination of waste (activities that do not add value)Strong customer orientation1. Large payoffs are possible from lean implementationCompatible with Six Sigma, which focuses on v
3、ariance reductionHistoryBased on Toyota Production System (TPS)1. Three important principles of TPSMinimizing waste in all formsContinuous improvement (pursuing perfection)Respect for workersA. Traditional systems compared with leanPrioritiesTraditional - Accept all orders and provide a large number
4、 of optionsLean - Target market is limited and product options are limited1. Product/service designTraditional - Engineers design custom outputs using new partsLean - Standard products are designed and then incrementally improved; designers consider manufacturability of product also (design for manu
5、facturability or design for assembly are key principles)Capacitya. Traditional - Extra capacities (equipment, overtime, partial shifts, large WIP) designed into the system just in case a problem arisesLean - Excess capacities (particularly WIP) kept to a minimumLarge work-in-process inventoryCant fi
6、nd needed parts1. Long lag time between decision to produce and start of productionPoor utilization of floor spaceLong lead times and poor on-time delivery performanceParts needed are not the ones in inventoryE. Suppliers Not Included in PlanningIL Applicability of JIT to J. Galt Lock CompanyCompany
7、 Appears to be Repetitive ManufacturerProblems Company Has are Kinds of Problems JIT can Help WithIII. Adopting Cellular Manufacturing Would Provide Much of InfrastructureNeeded to Successfully Implement JITJ. Galts Failure at Pull System is Likely Due to Not Having Proper InfrastructureLarge batch
8、sizes likely the result of large setup times1. Large travel distances resulting from functional layoutJumbled product flowsSuppliers not included in planningCellular Manufacturing Helps Provide Necessary Infrastructure1. Reduced setup times make it practical to produce in smaller batch sizesSmaller
9、batch sizes lead to increased flexibility, reduced work-in- process, and shorter lead timesShorter product lead times help to improve on-time delivery performance, facilitate more accurate forecasting, and provide a competitive advantageParts are produced in a single cell simplifying shop floor cont
10、rol and reducing part travel distancesIV. Problems Alleviated By Adopting JIT and Cellular ManufacturingEliminate Variety of Different Scheduling Techniques Used Throughout PlantEliminate Problems that Create the Need to Expedite PartsBetter Information and Shorter Lead Times will Help Eliminate Pro
11、blems of Producing Wrong Quantities and Not Having Correct Kanban CardsA. Cellular Manufacturing Will Eliminate Jumbled Flows and Large Part Travel DistancesReduced InventoryBetter utilization of floor spaceLess time spent looking for parts1. Shorter lead times resulting in better on-time delivery p
12、erformanceLess money tied up in inventorySuggested Cases/ReadingsCase: GE Thermocouple (Hvd. 5-689-019)This qualitative case concerns a manufacturing firm that is considering a project to reorganize the plant on a JIT basis. Issues involved include the workforce, customers, vendors, upper management
13、, the product and its quality, the infrastructure of the plant, and the production process.Case: Johnson Controls, Automotive Systems Group: The Georgetown, Kentucky Plant (Hvd. 9-693- 086, TN 5-693-102)Johnson is a supplier of seats to an automotive manufacturer and is moving to JIT deliveries of e
14、ntire seats rather than just sear parts. Allows students to understand the details of JIT delivery and JIT assembly.Case: EG&G Rotron Division (9-695-037, TN 5-697-100)Can be used to highlight issues related to implementing a strategy of competing on capabilities, or in a more detailed fashion, the
15、challenges of JIT production.Case: Bose Corporation: The JIT II Program (A) (Hvd. 9-694-001, TN 5-695-017)This speaker manufacturer is trying to decide on how much work to subcontract to a supplier and how much to do in-house. Presents the perspective from both that of the customer as well as that o
16、f the supplier.Videotape: Stockless Production (the Hewlett-Packard video on JIT)Although somewhat dated now, and difficult to find, this videotape on the operation and benefits of JIT is excellent and highly entertaining. The tape runs about 20 minutes and demonstrates why firms are going, or have
17、gone, to JIT as their production philosophy.Reading: Lean Consumption (J. P. Womack and D. T. Jones, Harvard Business Review, March 2005, pp. 58-68)This article extends lean thinking to the processes of consumer consumption. Lean consumption focuses on how business can meet customer needs without wa
18、sting their own or the customers time, effort, and resources.Reading: The Lean Service Machine (C. K. Swank, Harvard Business Review, October 2003, pp. 123- 129)This article discusses how Jefferson Pilot Financial (JPF) used a five-person lean team to reengineer its New Business operations using lea
19、n production principles. JPF built a model cell for processing insurance policies from independent advisers.Reading: Learning to Lead at Toyota (S. J. Spear, Harvard Business Review May 2004, pp. 78-86)This article follows the journey of a young American hired for an upper-level position at one of T
20、oyotas U.S. plants. This manager learned about the Toyota Production System fbr 3 months by learning how to observe work, to propose changes to that work, and to structure the proposed changes as experiments.Reading: JIT Manufacturing: A Survey of Implementations in Small and Large U.S. Manufacturer
21、s (R.E. White, J.N. Pearson, and J.R. Wilson, Management Science, Jan. 1999, pp. 1-15)This article updates the literature on JIT with examples of the experience of firms who have actually introduced JIT in their organizations.Reading: Does Manufacturing Need a JIT Revolution? (P.H. Zipkin, Harvard B
22、usiness Review, Jan.- Feb. 1991, Reprint # 91111)Identifies the basics of JIT and notes that an idea that is simple in concept can be much more complex in execution. Describes errors in implementation and what JIT is NOT.Reading: Whats Your Excuse for Not Using JIT? (R.C. Walleigh, Harvard Business
23、Review Mar.- Apr. 1986, pp. 39-54, Reprint #86214)Describes some of the unexpected benefits of JIT and how to implement a successful JIT program.Answers to ExercisesExercise 1Takt =Takt =510 20 308.5x30460255= 1.8 minutes/patientA1 Exercise 223 Mean Arrival Rate4 Break 15 Break 26 Lunch78 Takt Time
24、=91011 Takt Time:BCDE F G H1.803922 Minutes/patientExercise 2In the table shown below, the assumption cells are B3, B4, B5, & B6. The forecast cell is Bll.II (255 per day: Normally distributed with a sigma of255 30)10 (10 min. break: Uniformly distributed between 9 -13.5 minutes)10 (10 min. break: U
25、niformly distributed between 9-13.5 minutes) 30 | (30 min. break: Uniformly distributed between 28 - 34 minutes)Total Time Clinic is Open - Breakl Break 2 Lunch Time#ofArrivalsThe simulation was run 1,000 times. As shown in the output provided below, takt time ranged from 1.32 to 2.93 minutes/patien
26、t. The managerial implications of this simulation are as follows: (a) variability in time between patient arrivals, (b) variability in employee breaks, & (c) increased wait time for patients due to this variability. The clinic may have to add nurses if this wait time becomes excessive.Crystal Ball R
27、eport - TextbookEditionNot for Commercial UseSimulation started on 1/2/06 at12:05:52Simulation stopped on 1/2/06 at12:05:55Forecast: Takt Time:Summary:Display Range is from 1.34 to 2.39 minutesEntire Range is from 1.32 to 2.93 minutesAfter 1,000 Trials, the Std. Error of the Mean is 0.01Statistics:T
28、rialsMeanMedianModeStandard DeviationVarianceSkewnessKurtosisCoeff. of VariabilityRange MinimumRange MaximumRange WidthMean Std. ErrorCell:B12Crystal Ball Text book EditionNet for Commerciai Use1,000 TrialsForecast: Takt Time:Frequency ChartValue 10001.82 1.790.22 0.05 0.764.17 0.12 1.32 2.931.60 0.
29、01980 DisplayedT 31.031Frequencye三qpqodminutesExercise 3Effectiveness = Equipment Availability x Equipment Efficiency x Rate of Quality OutputEffectiveness = 0.95 x 0.75 x (1-0.03)= 0.6911 or 69.11%.Exercise 4In the table shown below, the assumption cells are B3, B4, & B5. The forecast cell is B8. T
30、he overall equipment effectiveness = (B3/12)*(B4/4)*(1-B5)123456781234567812345678ABExercise 4D E F GEquipment Availability:Equipment Rate:Scrap Rate: (Hours/day, Min. = 2, Most Likely = 10, Max. = 12)(Copies/second: Uniformly distributed between 2 - 4 copies/second) (Normally distributed with mean
31、of 0.03 and a sigma of 0.007)Overall Equipment Effectiveness:60.63%The simulation was run 1,000 times. As shown in the output provided below, the overall equipment effectiveness ranged from 10.69% to 90.25%. The managerial implications of this simulation are as follows: (a) copier output will vary w
32、idely and (b) long queues of jobs will likely build up.Crystal Ball Report - TextbookEditionNot for Commercial UseSimulation started on 1/2/06 at13:18:07Simulation stopped on 1/2/06 at13:18:09Forecast: Effectiveness:Summary:Display Range is from 10.69% to 90.25% %Entire Range is from 10.69% to 90.25
33、% %After 1,000 Trials, the Std. Error of the Mean is 0.53%Statistics:TrialsMeanMedianModeStandard DeviationVarianceSkewnessKurtosisCoeff. of VariabilityRange MinimumRange MaximumRange WidthMean Std. ErrorCell:B8Cell:B8Cell:B8Value 100048.25%47.07%16.90%2.86% 0.20 2.34 0.3510.69%90.25%79.56%0.53%Fore
34、cast: Effectiveness:1,000 Trials1,000 DisplayedFrequency Chart%FrequencyCrystal Ball Text book Edition Not for Commercial Use4. LayoutTraditional - Job shop approach using widely spread-out equipment (a spaghetti chart will show the long and excessive physical flows in the shop)Lean - Equipment is m
35、oved close togetherWorkforcea. Traditional - Employees have narrow responsibilities, spend most of their time on nonworking time looking for parts, moving materials, etc., and when they are actually working, they produce at a rapid pace whether or not their output is needed by the next workerLean -
36、Employees are flexible and produce only when the next worker is readyInventoriesTraditional - Inventories are large enough to buffer operations so that problems at one stage do not affect other stages; defective units become hidden in large inventories and managers devise production plans assuming a
37、 given defect rate in the planta. Lean - Inventories and storage spaces are reduced substantially; defective units cannot be hidden; setup time reduction tools, such as single minute exchange of die (SMED), are usedSuppliersTraditional - Practice has been to multi-source (pitting suppliers against o
38、ne another) to keep prices downLean - Single-sourcing is commonly used, thereby giving the supplier an incentive to help plan and to design parts, to make many small deliveries, and to locate nearby5. Planning & controlTraditional - Planning is the focus, is complex, & is computerized (MRP).a. Lean
39、- Control is the focus; MRP is used only to plan long lead- time itemsQualityTraditional - Approach is to inspect goods at critical points in the process and to track and plan for scrap ratesLean - Goal is zero defects; workers check parts as they hand off parts to next worker6. MaintenanceTradition
40、al - Corrective maintenance along with preventive maintenance performed by a group of expertsLean - Maintenance function assumes a greater role, with workers taking on many maintenance tasks, particularly preventive maintenanceIL Key Lean ConceptsA. Specify valueValue is the opposite of waste (overp
41、roduction, inventory, waiting, unnecessary transport, unnecessary processing, unnecessary human motions, & defects)Target cost - Based on how a customer defines value; Quality Function Deployment is useful for determining valueIdentify the value stream1. All activities (value-added and non-value-add
42、ed) from the creation of raw materials to the final delivery of the output to end customerValue stream within an organization - Design of output, operations function, & delivery to customerValue stream also should include suppliers, customer, distributors, etc.2. Categories for activitiesValue-added
43、Non-value-added but necessaryNon-value-added and not necessaryB. Make value flowContinuous flow manufacturingWork should flow without interruptionDelays associated with set up, moving work, & storing work must be eliminateda. Synchronize flow of work with takt time (available work time / customer re
44、quired volume)Converting to mixed-model assembly & sequencingItems produced throughout the day in small batchesa. For each product, divide monthly demand for each item by working days per month and then by number of shifts per day to determine daily production requirements per shiftFind the greatest
45、 common divisor for the daily production requirements per shift for each item and then divide the daily production requirements by the common divisor; this provides the amount of each item to produce in a cycleThe Theory of ConstraintsKey aspects - Identifying bottlenecks in a process & balancing th
46、e work flows in the processa. Guidelines - Balance flows; fluctuations in a tightly connected system add to each other; utilization of a non-bottleneck is determined by the constraint(s) in the system; utilizing a resource (using it to help the system create more output) differs from activating a re
47、source (keeping a resource busy but not increasing the system output); an hour lost at a bottleneck is an hour lost for the system; an hour saved at a non-bottleneck is a mirage; bottlenecks govern throughput; transfer batches should normally be smaller than process batches; the size of the process
48、batch should be variable at different resources; a shop schedule should be set by examining all shop constraints simultaneouslyFive-step improvement process - Identify the constraint; exploit the constraint; subordinate all else to the constraint; elevate the constraint; repeat the previous steps when a constraint is brokenPull value through the value streamActual customer demand drives the system1. Kanban system - Card or signal for communicating that more of a product is need