第八章 供应链的综合计划

1、PowerPoint presentation to accompanyChopra and Meindl Supply Chain Management, 5e1-1Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.1-1Copyright 20

2、13 Pearson Education, Inc. publishing as Prentice Hall.1-1Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.8-1Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.8Aggregate Planning in a Supply Chain8-2Copyright 2013 Pearson Education, Inc. publishing as Prentice Hal

3、l.Learning Objectives1. Identify the decisions that are best solved by aggregate planning.2. Understand the importance of aggregate planning as a supply chain activity.3. Describe the information needed to produce an aggregate plan.4. Explain the basic trade-offs to consider when creating an aggrega

4、te plan.5. Formulate and solve basic aggregate planning problems using Microsoft Excel.8-3Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Role of Aggregate Planning in a Supply ChainCapacity has a cost and lead times are often longAggregate planning: process by which a company det

5、ermines levels of capacity, production, subcontracting, inventory, stockouts, and pricing over a specified time horizon goal is to maximize profit decisions made at a product family (not SKU) level time frame of 3 to 18 months how can a firm best use the facilities it has?8-4Copyright 2013 Pearson E

6、ducation, Inc. publishing as Prentice Hall.Role of Aggregate Planning in a Supply ChainSpecify operational parameters over the time horizon Production rateSubcontracting WorkforceBacklog OvertimeInventory on hand Machine capacity levelAll supply chain stages should work together on an aggregate plan

7、 that will optimize supply chain performance8-5Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.The Aggregate Planning ProblemGiven the demand forecast for each period in the planning horizon, determine the production level, inventory level, and the capacity level for each period t

8、hat maximizes the firms (supply chains) profit over the planning horizonSpecify the planning horizon (typically 3-18 months)Specify the duration of each periodSpecify key information required to develop an aggregate plan8-6Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Informatio

9、n Needed foran Aggregate PlanAggregate demand forecast Ft for each Period t over T periodsProduction costs Labor costs, regular time ($/hr) and overtime ($/hr) Subcontracting costs ($/hr or $/unit) Cost of changing capacity hiring or layoff ($/worker), adding or reducing machine capacity ($/machine)

10、Labor/machine hours required per unitInventory holding cost ($/unit/period)Stockout or backlog cost ($/unit/period)Constraints overtime, layoffs, capital available, stockouts, backlogs, from suppliers8-7Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Outputs of Aggregate PlanProdu

11、ction quantity from regular time, overtime, and subcontracted timeInventory heldBacklog/stockout quantityMachine capacity increase/decreaseA poor aggregate plan can result in lost sales, lost profits, excess inventory, or excess capacity8-8Copyright 2013 Pearson Education, Inc. publishing as Prentic

12、e Hall.Identifying Aggregate Units of ProductionAggregate unit should be identified in a way that the resulting production schedule can be accomplished in practiceFocus on the bottlenecks when selecting the aggregate unit and identifying capacity and production timesAccount for activities such as se

13、tups and maintenance8-9Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsFamilyMaterial Cost/ Unit ($)Revenue/ Unit ($)Setup Time/Batch (hour)Average Batch SizeProduction Time/ Unit (hour)Net Production Time/Unit (hour)Percentage Share of Units SoldA15548505.605.7610

14、B73061503.003.0425C93981003.803.8820D124910504.805.0010E93661003.603.6620F13485754.304.3715Table 8-18-10Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsWeighted average approachMaterial cost per aggregate unit = 15 x 0.10 + 7 x 0.25 + 9 x 0.20 + 12 x 0.10 + 9 x 0.2

15、0 + 13 x 0.15 = $10SimilarlyRevenue per aggregate unit = $40Net production time per aggregate unit = 4.00 hours8-11Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Aggregate Planning StrategiesTrade-off between capacity, inventory, backlog/lost salesChase strategy using capacity as

16、 the leverTime flexibility from workforce or capacity strategy using utilization as the leverLevel strategy using inventory as the leverTailored or hybrid strategy a combination of strategies8-12Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Chase StrategyVary machine capacity or

17、 hire and lay off workers as demand variesOften difficult to vary capacity and workforce on short noticeExpensive if cost of varying capacity is highNegative effect on workforce moraleResults in low levels of inventoryUsed when inventory holding costs are high and costs of changing capacity are low8

18、-13Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Time Flexibility StrategyUse excess machine capacityWorkforce stable, number of hours worked variesUse overtime or a flexible work scheduleFlexible workforce, avoids morale problemsLow levels of inventory, lower utilizationUsed wh

19、en inventory holding costs are high and capacity is relatively inexpensive8-14Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Level StrategyStable machine capacity and workforce levels, constant output rateInventory levels fluctuate over timeInventories carried over from high to l

20、ow demand periodsBetter for worker moraleLarge inventories and backlogs may accumulateUsed when inventory holding and backlog costs are relatively low8-15Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Aggregate Planning Using Linear ProgrammingRed Tomato Tools Highly seasonal dem

21、and Develop a forecastMonthDemand ForecastJanuary1,600February3,000March3,200April3,800May2,200June2,200Table 8-28-16Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsItemCostMaterial cost$10/unitInventory holding cost$2/unit/monthMarginal cost of stockout/backlog$5/

22、unit/monthHiring and training costs$300/workerLayoff cost$500/workerLabor hours required4/unitRegular time cost$4/hourOvertime cost$6/hourCost of subcontracting$30/unitTable 8-38-17Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsDecision VariablesFor t = 1, ., 6Wt=

23、 Workforce size for month tHt= Number of employees hired at the beginning of month tLt= Number of employees laid off at the beginning of month tPt= Production in month tIt= Inventory at the end of month tSt= Number of units stocked out at the end of month tCt= Number of units subcontracted for month

24、 tOt= Number of overtime hours worked in month t8-18Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsObjective FunctionMinimize(Regular-time labor cost + Overtime labor cost + Cost of hiring and layoffs + Cost of holding inventory + Cost of stocking out + Cost of su

25、bcontracting + Material cost)Min640Wtt=16+6Ott=16+300Htt=16+500Ltt=16+2Itt=16+5Stt=16+10Ptt=16+30Ctt=168-19Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsConstraints1. Workforce, hiring, and layoff constraintsAll for t = 1,., 6Wt=Wt1+HtLt2. Capacity constraintsPt

26、40Wt+Ot43. Inventory balance constraintsIt1+Pt+Ct=Dt+St1+ItSt4. Overtime limit constraintsOt10Wt8-20Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsAverage inventory =(I0+IT) / 2+Itt=1T1()T=(I0+IT) / 2+Itt=1T1()T Dtt=1T1()TAverage timein inventory8-21Copyright 2013

27、 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsTotal cost over planning horizon = $422,275Revenue over planning horizon = 40 x 16,000 = $640,000Period, tNo. Hired, HtNo. Laid Off, LtWorkforce Size, WtOvertime, OtInventory, ItStockout, StSubcontract, CtTotal Production, Pt000800

28、1,0000010156501,983002,5832006501,567002,583300650950002,583400650026702,583500650117002,583600650500002,583Table 8-48-22Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato Tools=(I0+I6) / 2+Itt=15()T=5,3676= 895Average seasonal inventoryAverage flow time =8952,667= 0.34 =

29、0.34 months8-23Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsHigher demand variabilityMonthDemand ForecastJanuary1,000February3,000March3,800April4,800May2,000June1,400Table 8-5=(I0+IT) / 2+Itt=1T1()T=6,4506=1,075Average seasonal inventory8-24Copyright 2013 Pears

30、on Education, Inc. publishing as Prentice Hall.Red Tomato ToolsTotal cost over planning horizon = $432,858Period, tNo. Hired, HtNo. Laid Off, LtWorkforce Size, WtOvertime, OtInventory, ItStockout, StSubcontract, CtTotal Production, Pt0008001,0000010156502,583002,5832006502,167002,583300650950002,583

31、40065001,26702,583500650068302,583600650500002,583Table 8-6Average flow time =1,0752,667= 0.40 months8-25Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsLower hiring and layoff costs=(I0+IT) / 2+Itt=1T1()T=2,5006= 417Average seasonal inventoryAverage flow time =417

32、2,667= 0.16 monthsTotal cost over planning horizon = $412,6888-26Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Red Tomato ToolsPeriod, tNo. Hired, HtNo. Laid Off, LtWorkforce Size, WtOvertime, OtInventory, ItStockout, StSubcontract, CtTotal Production, Pt0008001,0000010354501,20

33、0002,2672004500002,2673420870300002,26740087001,26702,267502661025068302,267600610500002,267Table 8-78-27Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Forecast Error in Aggregate PlansForecast errors must be consideredSafety inventorySafety capacity Use overtime as a form of saf

34、ety capacity Carry extra workforce permanently as a form of safety capacity Use subcontractors as a form of safety capacity Build and carry extra inventories as a form of safety inventory Purchase capacity or product from an open or spot market as a form of safety capacity8-28Copyright 2013 Pearson

35、Education, Inc. publishing as Prentice Hall.Aggregate Planning In ExcelFor t = 1, ., 6Wt= Workforce size for Month tHt= Number of employees hired at the beginning of Month tLt= Number of employees laid off at the beginning of Month tPt= Production in Month tIt= Inventory at the end of Month tSt= Num

36、ber of units stocked out at the end of Month tCt=Number of units subcontracted for Month tOt=Number of overtime hours worked in Month t8-29Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Aggregate Planning In ExcelFigure 8-18-30Copyright 2013 Pearson Education, Inc. publishing as

37、Prentice Hall.Aggregate Planning In ExcelFigure 8-28-31Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Aggregate Planning In ExcelFigure 8-38-32Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.Aggregate Planning In ExcelFigure 8-48-33Copyright 2013 Pearson Educat

38、ion, Inc. publishing as Prentice Hall.Building a Rough Master Production ScheduleDisaggregate an aggregate planFamilySetup Time/Batch (hour)Average Batch SizeProduction Time/Unit (hour)Production QuantityNumber of SetupsSetup Time (hours)Production Time (hours)A8505.602585401,445B61503.006464241,938C81003.805175401,965D10504.802585501,238E61003.605175301,861F5754.303875251,664Table 8-88-34Copyright 2013 Pearson Education, Inc. publishing as Prentice Hall.The Role of IT in Aggregate PlanningThe ability to handle large problemsThe ability to handle complex problems (through either nonline