AggregratePlanning12.ppt

1、Aggregate Planning,Chapter 12,Core MRP II,MANUFACTURING RESOURCE PLANNING,Aggregate Planning Strategies,Maintain a level workforce Maintain a steady output rate Match demand period by period Use a combination of decision variables,Basic Strategies,Level capacity: Maintaining a steady rate of regular

2、-time output while meeting variations in demand by a combination of options. Chase demand: Matching capacity to demand; the planned output for a period is the expected demand for that period.,Master schedule: The result of disaggregating an aggregate plan; shows quantity and timing of specific end i

3、tems for a scheduled horizon. Rough-cut capacity planning: Approximate balancing of capacity and demand to test the feasibility of a master schedule.,Disaggregating,Master Scheduling Process,Time Fences in MPS,Aggregate Production Planning,Aggregate Versus Detailed Plans Costs Of Production Chase, L

4、evel, And Mixed Strategies,Aggregate Versus Detailed Plans,Plans differ in terms of detail and planning horizons The aggregate production plan has a moderate horizon but little detail E.g., Plan overall facility production month-by-month for the the next 18 months The master production schedule has

5、a short horizon but great detail E.g., Plan production for each product week-by-week for the next 12 weeks,Aggregate Versus Detailed Plans,Why plan aggregate production levels? Aggregate plans do not provide detail needed to run facility But detail unnecessary for medium-range resource deployment de

6、cisions Labor force size Financing inventory Aggregate forecasts are more accurate than detailed forecasts,Aggregate Versus Detailed Forecasts,Sales forecasts can be aggregated with respect to time:,Sales forecasts can be aggregated with respect to time:,Aggregate Versus Detailed Forecasts,Sales for

7、ecasts can be aggregated with respect to product:,Aggregate Versus Detailed Forecasts,Sales forecasts can be aggregated with respect to product:,Aggregate Versus Detailed Forecasts,Why? Aggregate forecasts are more accurate than individual detailed forecasts,Aggregate Versus Detailed Forecasts,Why?

8、Aggregate forecasts are more accurate than individual detailed forecasts,Aggregate Versus Detailed Forecasts,Use aggregate forecasts for planning medium-range overall production levels. High long-range forecast accuracy Detail not needed for planning long-range resource use (labor, inventory, etc.)

9、Use detailed forecasts for initial detailed short-range Master Production Schedule (MPS) Detailed forecasts reasonably accurate for this time frame Need product-specific detail for MPS,Aggregate Versus Detailed Forecasts,The Aggregate Production Plan,Consider the following aggregate demand forecast:

10、 The plan is stated in the the common unit of capacity direct labor hours,Suppose we want to try to match demand:,The Aggregate Production Plan,Suppose we want to try to match demand: How do we “cost out” the plan?,The Aggregate Production Plan,First need some more information:,The Aggregate Product

11、ion Plan,“Projected Available Balance” is simply the estimated ending inventory for each period,The Aggregate Production Plan,The # workers needed is based on the planned production and average worker productivity here, it is 500 DLH/Worker/Quarter,The Aggregate Production Plan,Costs Of Maintaining

12、And Changing Production Levels,Costs of keeping production steady: Ch - Holding cost ($ / DLH / quarter) Cb - Backorder cost ($ / DLH / quarter) Costs of changing production CH - Hiring cost ($ / Worker) CF - Firing cost ($ / Worker) Also need to worry about: CR - Wage rate ($ / DLH / period),The Ag

13、gregate Production Plan,For our example, the wage rate is $10/DLH,The hiring and firing costs are $2000 and $500, respectively,The Aggregate Production Plan,Holding and backorder costs are $1 and $3 /DLH/Quarter, respectively,The Aggregate Production Plan,Which gives us a projected cost of $400,000

14、for the year,The Aggregate Production Plan,Chase, Level, & Mixed Strategies,This example is the first of the two pure strategies Chase strategy: make only as much as you can sell The other pure strategy has a different cost structure Level strategy: maintain a steady production rate In reality, a fi

15、rms strategy will be a combination or mixture of chase and level,A level strategy will absorb fluctuations in demand through fluctuations in inventory,The Aggregate Production Plan,A level strategy will absorb fluctuations in demand through fluctuations in inventory,The Aggregate Production Plan,A level strategy will absorb fluctuations in demand through fluctuations in inventory,The Aggregate Production Plan,A level strategy will absorb fluctuations in demand through fluctuations in inventory,The Aggregate