供应链管理英文课件：Ch08 Aggregate Planning in the Supply Chain

1、8-1,Chapter 8Aggregate Planningin the Supply Chain,Supply Chain Management(3rd Edition),8-2,Importance of Aggregate Planning,Without a sufficiently long-term view one may make short-term decisions that hurt the organization in the long-term,8-3,Importance of Aggregate Planning,Aggregate planning at

2、Henry Ford Hospital involves matching available capacity, workers, and supplies to a highly variable customer demand pattern,8-4,Importance of Aggregate Planning,Aggregate planning at Henry Ford Hospital involves matching available capacity, workers, and supplies to a highly variable customer demand

3、 pattern 903 beds arranged into 30 nursing units Cost $5,000 of turning away a patient (simple cases) Cost of one idle 8-bed module is $35,000/month or $420,000/year High degree of demand variability Demand for beds could change by as many as 16% in less than two weeks,8-5,Importance of Aggregate Pl

4、anning,Shortly afterHenry Ford Hospitalreduced staff, it determined the staff was needed New staff was recruited Both staff reduction and recruiting costs were incurred,8-6,Aggregate Planning,Aggregate planning involves aggregate decisions rather than stock-keeping unit (SKU)-level decisions for a m

5、edium term planning horizon (3-18 months),All-Terrain Vehicle (ATV),EngineAssembly,Transmission,Model A,Model B,Model C,Automatic,Manual,8-7,Outline,Role of aggregate planning in a supply chain The aggregate planning problem Aggregate planning strategies Implementing aggregate planning in practice,8

6、-8,Role of Aggregate Planning in a Supply Chain,Capacity has a cost, lead times are greater than zero Aggregate planning: process by which a company determines levels of capacity, production, subcontracting, inventory, stockouts, and pricing over a specified time horizon goal is to maximize profit d

7、ecisions 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?,8-9,Role of Aggregate Planning in a Supply Chain,Specify operational parameters over the time horizon: production rate workforce overtime machine capacity level subcontractin

8、g backlog inventory on hand All supply chain stages should work together on an aggregate plan that will optimize supply chain performance,8-10,The Aggregate Planning Problem,Given the demand forecast for each period in the planning horizon, determine the production level, inventory level, and the ca

9、pacity level (internal and outsourced) for each period that maximizes the firms profit over the planning horizon To create an aggregate plan, a company must Specify the planning horizon (typically 3-18 months) Specify the duration of each period Specify key information required to develop an aggrega

10、te plan,8-11,Information Needed foran Aggregate Plan,Demand forecast in each period Production costs labor costs, regular time ($/hr) and overtime ($/hr) subcontracting costs ($/hr or $/unit) cost of changing capacity: hiring or layoff ($/worker) and cost of adding or reducing machine capacity ($/ma

11、chine) Labor/machine hours required per unit Inventory holding cost ($/unit/period) Stockout or backlog cost ($/unit/period) Constraints: limits on overtime, layoffs, capital available, stockouts and backlogs,8-12,Outputs of Aggregate Plan,Production quantity from regular time, overtime, and subcont

12、racted time: used to determine number of workers and supplier purchase levels Inventory held: used to determine how much warehouse space and working capital is needed Backlog/stockout quantity: used to determine what customer service levels will be Machine capacity increase/decrease: used to determi

13、ne if new production equipment needs to be purchased A poor aggregate plan can result in lost sales, lost profits, excess inventory, or excess capacity,8-13,Aggregate Planning Strategies,Trade-off between capacity, inventory, backlog/lost sales Basic strategies: Level strategy (using inventory as le

14、ver) Synchronize production rate with long term average demand Swim wear Chase (the demand) strategy (using capacity as lever) Synchronize production rate with demand Fast food restaurants Time flexibility strategy (using utilization as lever) High levels excess (machine and/or workforce) capacity a

15、rmy Mixed strategy strategy Combination of the chase, level, and time flexibility strategies,8-14,Level Strategy,Maintain stable machine capacity and workforce levels with a constant output rate Shortages and surpluses result in fluctuations in inventory levels over time Either inventories are built

16、 up in anticipation of future demand or backlogs are carried over from high to low demand periods Better for worker morale Large inventories and backlogs may accumulate Should be used when inventory holding and backlog costs are relatively low,8-15,Chase Strategy,Production rate is synchronized with

17、 demand by varying machine capacity or hiring and laying off workers as the demand rate varies However, in practice, it is often difficult to vary capacity and workforce on short notice Expensive if cost of varying capacity is high Negative effect on workforce morale Results in low levels of invento

18、ry Should be used when inventory holding costs are high and costs of changing capacity are low,8-16,Time Flexibility Strategy,Can be used if there is excess machine capacity Workforce is kept stable, but the number of hours worked is varied over time to synchronize production and demand Can use over

19、time or a flexible work schedule Requires flexible workforce, but avoids morale problems of the chase strategy Low levels of inventory, lower utilization Should be used when inventory holding costs are high and capacity is relatively inexpensive,8-17,Case Study Results,In general, the chase strategy

20、 is used when Products are valuable Products are bulky or hard to store Products are perishable or carry an appreciable risk of obsolescence High variety Accurate sales predictions are hard to obtain making stockpiling hazardous Fashion items In general, the level strategy is used when Operators tak

21、e a long time to become proficient at critical tasks Products with negligible probability of obsolescence Low variety Forecasts are quite good,8-18,Generic tool, call it Shovel,Example: Aggregate planning at RedTomatoTools,RedTomatoTools A small manufacturer of gardening equipment,Shovels Spades For

22、ks,8-19,Inputs of an Aggregate Plan,Demand forecast in each period Production costs labor costs, regular time ($/hr) and overtime ($/hr) subcontracting costs ($/hr or $/unit) cost of changing capacity: hiring or layoff ($/worker) and cost of adding or reducing machine capacity ($/machine) Other cost

23、s Labor/machine hours required per unit Inventory holding cost ($/unit/period) Stockout or backlog cost ($/unit/period),8-20,Example: Red Tomato Tools,Constraints Workforce, hiring, and layoff constraints Capacity constraints Inventory balance constraints Overtime limit constraints Inventory at end

24、of Period 6 is at least 500 Stockout at end of Period 6 equals 0,8-21,Aggregate Planning at Red Tomato Tools,8-22,Aggregate Planning at Red Tomato Tools,Fundamental Tradeoffs in Aggregate Planning Capacity (regular time, overtime, subcontract) Inventory Backlog / lost sales Basic Strategies Chase st

25、rategy Time flexibility from workforce or capacity Level strategy,8-23,Aggregate Planning,8-24,Aggregate Planning (Define Decision Variables),Wt = Workforce size for month t, t = 1, ., 6 Ht = Number of employees hired at the beginning of month t, t = 1, ., 6 Lt = Number of employees laid off at the

26、beginning of month t, t = 1, ., 6 Pt = Production in month t, t = 1, ., 6 It = Inventory at the end of month t, t = 1, ., 6 St = Number of units stocked out at the end of month t, t = 1, ., 6 Ct = Number of units subcontracted for month t, t = 1, ., 6 Ot = Number of overtime hours worked in month t, t = 1, ., 6,8-25,Aggregate Planning(Define Objective Function),8-26,Aggregate Planning (Define Constraints Linking Variables),Workforce size for each month is based on hiring and layoffs,8-27,Aggregate Planning (Constraints),Production for each month cannot exceed capacity,8-28,A