Internet Case Study for Chapter 13: Aggregate Pl=
anning
Cornwell Glass
Cornwell Glass produces replacement automobile glass for all makes of ca= rs. Cornwell has a sophisticated forecasting system that uses data from past ye= ars to find seasonal factors and long-term trends. The system uses data from past weeks to find recent trends. The following table presents the forecasted demands for the coming year on a weekly basis.
|
Week |
|
Demand |
Week |
|
Demand |
|
April |
15 |
1,829 |
November |
4 |
1,864 |
|
|
22 |
1,820 |
|
11 |
1,989 |
|
|
29 |
1,887 |
|
18 |
2,098 |
|
May |
6 |
1,958 |
|
25 |
2,244 |
|
|
13 |
2,011 |
December |
2 |
2,357 |
|
|
20 |
2,063 |
|
9 |
2,368 |
|
|
27 |
2,104 |
|
16 |
2,387 |
|
June |
3 |
2,161 |
|
23 |
2,402 |
|
|
10 |
2,258 |
|
30 |
2,418 |
|
|
17 |
2,307 |
January |
6 |
2,417 |
|
|
24 |
2,389 |
|
13 |
2,324 |
|
July |
1 |
2,434 |
|
20 |
2,204 |
|
|
8 |
2,402 |
|
27 |
2,188 |
|
|
15 |
2,385 |
February |
3 |
2,168 |
|
|
22 |
2,330 |
|
10 |
2,086 |
|
|
29 |
2,323 |
|
17 |
1,954 |
|
August |
5 |
2,317 |
|
24 |
1,877 |
|
|
12 |
2,222 |
March |
3 |
1,822 |
|
|
19 |
2,134 |
|
10 |
1,803 |
|
|
26 |
2,065 |
|
17 |
1,777 |
|
September |
2 |
1,973 |
|
24 |
1,799 |
|
|
9 |
1,912 |
|
31 |
1,803 |
|
|
16 |
1,854 |
April |
7 |
1,805 |
|
|
23 |
1,763 |
|
|
|
|
|
30 |
1,699 |
|
|
|
|
October |
7 |
1,620 |
|
|
|
|
|
14 |
1,689 |
|
|
|
|
|
21 |
1,754 |
|
|
|
|
|
28 |
1,800 |
|
|
|
Cornwell uses these forecasts for its production planning. It manufactur= es several types of glass, and demand is aggregated across products and measur= ed in pounds.
It is obvious from the demands that there is a great deal of seasonality/cyclicality in the demand pattern. Cornwell will need to take t= his into account in developing a production plan for the coming year.
Cornwell must consider the costs of hiring or firing workers; using overtime; subcontracting; and holding inventory or running out of the produ= ct. The holding cost for glass is $.12 per pound per week. The company estimates that the cost of a late order is $20 per pound per week late.
Cornwell currently costs out each hire at $5.63 per pound (based on trai= ning costs and production rates per worker). It costs out each fire at $15.73 per pound (based on unemployment compensation and loss of good will). The compa= ny currently has the capacity to manufacture 1,900 pounds of glass per week. T= his capacity cannot be exceeded under any plan. At most, 2,000 pounds can be subcontracted in a given week, and overtime is limited to 250 pounds per we= ek. Glass that is manufactured during overtime costs $8 per pound more than gla= ss manufactured during regular time. Glass that is subcontracted costs $2 more= per pound than glass that is produced during overtime.
The current inventory is 73 units, and currently production is working at full capacity, 1,900 units. Cornwell has not been able to determine whether demands not met in the current month can be met later or whether these orde= rs are lost.
DISCUSSION QUESTIONS
1. Find the production schedule Cornwell should follow under the various assumptions and policies, and detail the differenc= es among these schedules.