OPERATIONS MANAGEMENT
CHAPTER 11 PROBLEMS
Aggregate Planning & Scheduling
Calculations
Problem 1:
Prepare a Master Schedule given the
following information:
● The forecast for each week for an
eight-week schedule is 75 units.
● The Master Production Schedule (MPS) rule is to schedule production if the projected
on-hand inventory would be negative without it.
● Committed customer orders are as follows:
WeeWeek
CjusCustomer order
1
75
2
53
3
26
4
18
Use a production lot size of 100 units and no beginning inventory.
Week
Beginning inventory=0
1
2
4
5
3
Qty. on Hand (Beg. Inventory 0
25
50
75
0
week on week)
Forecast
75
75
75
75
75
Customer Orders
75
53
26
18
0
Max (Forecast/ Customers
75
75
75
75
75
Orders)
Projected On-Hand Inventory 25
50
75
0
25
MPS (Previous Week
Inventory MPS-(Forecast
Customer order))
MPS Quantity
100 100
100
0
100
6
25
7
50
8
75
75
0
75
75
0
75
75
0
75
50
75
0
100
100
0
Formulas for Projected On-Hand Inventory
Week 1 = Beginning Inventory + MPS – MAX (Forecast:Customer Order)
Highest number
Weeks 2 – 8 = Previous Week Inventory + MPS – (Forecast: Customer Order)
1
Because the problem says we cannot have any negative inventory, then we require MPS
shipments to come in. When a shipment comes in, it is in lots of 100. In this problem, MPS will
be added for Weeks 1,2,3, and Weeks 5, 6, 7. No MPS shipments are expected in Week 4 or
Week 8.
Problem 2:
Given the following Master Schedule:
Week 7
Safety stock
SS=0
Beg. Of
Invent. = 0
Period
1
2
3
4
5
6
7
8
Forecast
75
75
75
75
75
75
75
75
Customer Orders
75
53
26
18
0
0
0
0
25
50
75
0
25
50
75
0
25
Projected On-Hand
Hand Inventory PIOH
Inventory on hand
IOH
50
75
0
25
50
75
75
50
25
0
75
50
25
0
Net Requirement NR
75
50
25
0
75
50
25
0
MPS
ATP
100
25
100
100
74
0
0
100
100
100
100
100
100
0
0
Requirement
Q=lot=size=0
0
47
Use production lot size of 100 units and no beginning inventory. Inventory is counted as physical
inventory. Week 4 & Week 8 no MPS is planned, it stays 0.
Determine the available to promise (ATP) quantities for each week.
Shown above
The ATP quantities can be presented to the Marketing Department to promise customers the
number of units to be manufactured by a specific date.
Week 4 & Week 8 no MPS is planned, it stays 0.
Formula: Week 1
Week 2
ATP = Beginning Inventory + MPS – Customer Order
ATP = MPS – Customer Order
Shown above.
2
In Week 3, we must add customer orders for Wk3 and Wk 4 because they are scheduled but Wk
4 no MPS is scheduled. So, our next MPS will not occur until Wk 5. The rule is to count
scheduled orders until the next MPS. This occurs again in Week 7, we add customer orders for
Wk7 and Wk8 and subtract them from MPS.
Week 3 ATP = MPS – (Wk3 + Wk4)
Shown above.
3