Chapter 12 – MRP and ERP
12–41
12. Given:
200 carts must be ready at the beginning of week 8. The product structure tree, assembly time
chart, and inventory information are shown in the solutions below:
a. Product structure tree:
Frame
Assembly Time Chart
Motor
Frame
Supports
Cover
Cart
2 3 4 5 6 7
week
Golf
Cart
Top
b.
Start of week 8
Start of week 2
Chapter 12 – MRP and ERP
c. Develop a material requirements plan that will provide 200 golf carts by week 8 assuming
lot-for-lot ordering.
Master
Schedule for:
Golf Cart
Week
1
2
3
4
5
7
Quantity
Golf Cart LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
7
Gross requirements
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
Net requirements
Planned-order receipts
Planned-order releases
200
Top LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
7
Gross requirements
200
Scheduled receipts
Projected on hand
40
40
40
40
40
40
40
Net requirements
160
Planned-order receipts
160
Planned-order releases
Notes: Gross Requirements (week 7) = Planned-Order Releases of 200 Golf Carts * 1 = 200.
Supports(4) LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
7
Gross requirements
Scheduled receipts
Projected on hand
200
200
200
200
200
200
0
Net requirements
Planned-order receipts
Planned-order releases
440
12–43
12. c. (continued)
Cover LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
4
5
6
7
Gross requirements
160
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
Net requirements
160
Planned-order receipts
160
Planned-order releases
160
Base LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
4
5
6
7
Gross requirements
200
Scheduled receipts
Projected on hand
20
20
20
20
20
20
20
Net requirements
180
Planned-order receipts
180
Planned-order releases
180
Notes: Gross Requirements (week 7) = Planned-Order Releases of 200 Golf Carts * 1 = 200.
Motor LT = 2
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
4
5
6
7
Gross requirements
180
Scheduled receipts
Projected on hand
300
300
300
300
300
300
120
Net requirements
Planned-order receipts
Planned-order releases
Notes: Gross Requirements (week 6) = Planned-Order Releases of 180 Bases * 1 = 180.
12–44
12. c. (Continued)
Body LT = 3
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
4
5
6
7
Gross requirements
180
Scheduled receipts
Projected on hand
50
50
50
50
50
50
0
Net requirements
130
Planned-order receipts
130
Planned-order releases
Notes: Gross Requirements (week 6) = Planned-Order Releases of 180 Bases * 1 = 180.
Seats(2) LT = 2
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
4
5
6
7
Gross requirements
360
Scheduled receipts
Projected on hand
120
120
120
120
120
120
0
Net requirements
240
Planned-order receipts
240
Planned-order releases
240
Notes: Gross Requirements (week 6) = Planned-Order Releases of 180 Bases * 2 = 360.
Frame LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
4
5
6
7
Gross requirements
Scheduled receipts
Projected on hand
35
35
35
0
0
0
0
Net requirements
Planned-order receipts
Planned-order releases
95
Notes: Gross Requirements (week 3) = Planned-Order Releases of 130 Body * 1 = 130.
12–45
12. c. (Continued)
Controls LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
130
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
130
Planned-order receipts
130
Planned-order releases
130
Notes: Gross Requirements (week 3) = Planned-Order Releases of 130 Body * 1 = 130.
Wheel Assemblies(4) LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
520
Scheduled receipts
Projected on hand
240
240
240
240
0
0
0
0
0
Net requirements
280
Planned-order receipts
280
Planned-order releases
280
Notes: Gross Requirements (week 3) = Planned-Order Releases of 130 Body * 4 = 520.
Scheduled receipts
Projected on hand
Net requirements
100
100
Planned-order receipts
100
100
Planned-order releases
100
100
Gross requirements
100
100
100
Net requirements
100
100
Planned-order receipts
100
100
13. Given:
Refer back to Problem 12. The revised plan calls for 100 golf carts to be available at the start of
week 6, 100 at the start of week 8, and 100 at the start of week 9.
a. Develop a master schedule for this revised plan.
Master
Schedule for:
Golf Carts
Week
1
2
3
4
5
6
7
8
9
Quantity
100
100
100
b. Determine the timing and quantities for orders for tops and bases.
Golf Cart LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
9
Gross requirements
100
100
100
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
0
Net requirements
100
100
100
Planned-order receipts
100
100
100
Planned-order releases
100
100
100
Chapter 12 – MRP and ERP
c. The firm’s capacity limits the assembly of bases to 50 units per week. Revise the plan, but
Planned Order-Receipts (week 7) = 100
Planned Order-Receipts (week 5) = 80
Given the capacity limit of 50 per week, we could divide the Planned-Order Receipts as
follows:
Week 8 (100): Week 7 (50) & Week 8 (50)
schedule them automatically.
Master
Schedule for:
Golf Carts
Week
1
2
3
4
5
6
7
8
9
Quantity
100
100
100
Chapter 12 – MRP and ERP
12–49
Education.
Top Blade Assembly
LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
600
Scheduled receipts
Projected on hand
40
40
40
40
40
40
0
0
0
Net requirements
560
Planned-order receipts
560
Planned-order releases
560
Notes: Gross Requirements (week 5) = Planned-Order Releases of 600 Scissors * 1 = 600.
Screw LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
600
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
600
Planned-order receipts
600
Planned-order releases
600
Straight Blade LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
600
Scheduled receipts
Projected on hand
200
200
200
200
200
0
0
0
0
Net requirements
400
Planned-order receipts
400
Planned-order releases
400
Notes: Gross Requirements (week 4) = Planned-Order Releases of 600 Bottom Blade Assembly * 1 =
600.
Chapter 12 – MRP and ERP
12–50
Education.
Straight Plastic Grip
LT = 2
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
600
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
600
Planned-order receipts
600
Planned-order releases
600
Notes: Gross Requirements (week 4) = Planned-Order Releases of 600 Bottom Blade Assembly * 1 =
600.
Bent Blade LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
560
Scheduled receipts
Projected on hand
350
350
350
350
350
0
0
0
0
Net requirements
210
Planned-order receipts
210
Planned-order releases
210
Notes: Gross Requirements (week 4) = Planned-Order Releases of 560 Top Blade Assembly * 1 = 560.
Bent Plastic Grip LT = 2
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
560
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
560
Planned-order receipts
560
Planned-order releases
560
Notes: Gross Requirements (week 4) = Planned-Order Releases of 560 Top Blade Assembly * 1 = 560.