Chapter 12 – MRP and ERP
12–59
H(3) LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
240
720
Scheduled receipts
50
Projected on hand
0
0
50
50
0
0
0
0
0
Net requirements
190
720
Planned-order receipts
190
720
Planned-order releases
190
720
Notes:
Gross Requirements (week 3) = Planned-Order Releases of 80 E * 3 = 240.
Gross Requirements (week 5) = Planned-Order Releases of 240 E * 3 = 720.
Case: Promotional Novelties
Given:
Promotional Novelties has received an order for 20,000 toy Tractor-Trailers to be ready at the beginning
of week 8. The company can complete final assembly of the Tractor-Trailers at a rate of 10,000 a week.
Tractors and Trailers are purchased and have a lead time = 3 weeks. The company has sufficient supply of
2 to 3 weeks. All items use lot-for-lot ordering except for the purchased Wheels (lot size = multiples of
6,400).
Comments on the product structure tree shown in the text:
The Wheel Assembly of the Tractor differs from the Wheel Assembly of the Trailer.
If the order of 20,000 tractor-trailers is due at the start of week 8 and final assembly is limited to 10,000
per week, then we must list 10,000 in week 7 and 10,000 in week 8 of the master schedule.
Chapter 12 – MRP and ERP
12–60
Education.
Master
1
2
3
4
5
6
7
8
Schedule
10,000
10,000
Tractor-Trailer
LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
10,000
10,000
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
10,000
10,000
Planned-order receipts
10,000
10,000
Planned-order releases
10,000
10,000
Tractor LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
10,000
10,000
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
10,000
10,000
Planned-order receipts
10,000
10,000
Planned-order releases
10,000
10,000
Trailer LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
10,000
10,000
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
10,000
10,000
Planned-order receipts
10,000
10,000
Planned-order releases
10,000
10,000
Chapter 12 – MRP and ERP
12–61
Education.
Tractor Wheel
Assembly LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
10,000
10,000
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
10,000
10,000
Planned-order receipts
10,000
10,000
Planned-order releases
10,000
10,000
Trailer Wheel
Assembly LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
10,000
10,000
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
10,000
10,000
Planned-order receipts
10,000
10,000
Planned-order releases
10,000
10,000
Chapter 12 – MRP and ERP
12–62
Education.
Wheels (6) & (12)
LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
180,000
180,000
Scheduled receipts
Projected on hand
0
0
0
0
100,000
20,000
4,000
4,000
4,000
Net requirements
80,000
160,000
Planned-order receipts
100,000
100,000
100,000
64,000*
Planned-order releases
100,000
64,000*
100,000
100,000
Notes:
Gross Requirements (week 4) = Planned-Order Releases of (10,000 Tractor Wheel Assembly * 6) +
(10,000 Trailer Wheel Assembly * 12) = 60,000 + 120,000 = 180,000.
Gross Requirements (week 5) = Planned-Order Releases of (10,000 Tractor Wheel Assembly * 6) +
1. The company will need a total of 360,000 Wheels. It will be able to produce only 300,000 during
2. The company will need the Wheels in week 5. If lead time will be 2-3 weeks, then assume that it
will be 3 weeks, and order the Wheels from the supplier in week 2.
Chapter 12 – MRP and ERP
12–63
Case: DMD Enterprises
Given:
Marty wants to assemble 15 Arrows and 10 Darts each week to have them ready at the start of weeks 4
through 8. The product structure trees are given in the text along with inventory information on lead
times, on hand amounts, and lot sizing rules. Scheduled Receipts: Arrows = 20 in week 1 & W = 18 in
week 1. Darts = 20 in week 2 & F = 15 in week 2. Develop the material plans for all items.
Master
Schedule for:
Arrows
Week
1
2
3
4
5
6
7
8
Quantity
15
15
15
15
15
Master
Schedule for:
Darts
Week
1
2
3
4
5
6
7
8
Quantity
10
10
10
10
10
Arrows LT = 2
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
15
15
15
15
15
Scheduled receipts
20
Projected on hand
5
25
25
25
25
10
0
0
0
Net requirements
5
15
15
15
Planned-order receipts
5
15
15
15
Planned-order releases
5
15
15
15
Darts LT = 2
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
10
10
10
10
10
Scheduled receipts
20
Projected on hand
2
2
22
22
22
12
2
0
0
Net requirements
8
10
10
Planned-order receipts
8
10
10
Planned-order releases
8
10
10
X LT = 1
Lot size: Multiples of 25
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
5
15
15
15
Scheduled receipts
Projected on hand
5
5
5
5
0
10
20
5
5
Net requirements
15
5
Planned-order receipts
25
25
Planned-order releases
25
25
Chapter 12 – MRP and ERP
12–64
Education.
Case: DMD Enterprises (continued)
M LT = 1
Lot size: Lot-for-lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
5
15
15
15
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
5
15
15
15
Planned-order receipts
5
15
15
15
Planned-order releases
5
15
15
15
K(2) LT = 1
Lot size: Lot-for-lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
16
20
20
Scheduled receipts
Projected on hand
3
3
3
3
3
0
0
0
0
Net requirements
13
20
20
Planned-order receipts
13
20
20
Planned-order releases
13
20
20
F & F LT = 1
Lot size: Multiples of 30
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
25
33
10
10
Scheduled receipts
15
Projected on hand
10
10
25
25
0
27
17
7
7
Net requirements
33
0
0
Planned-order receipts
60
Planned-order releases
60
Chapter 12 – MRP and ERP
W & W(2) LT* = 2 or 3
Lot size: Multiples of 12
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
31
55
55
15
Scheduled receipts
18
Projected on hand
2
20
20
20
1
6
11
8
8
Net requirements
11
54
49
4
Planned-order receipts
12
60
60
12
Planned-order releases
72
60
12
Notes:
Gross Requirements (week 3) = Planned-Order Releases of (5 Arrows *1) + (13 K * 2) = 5 + 26 =
31.
Gross Requirements (week 4) = Planned-Order Releases of (15 Arrows * 1) + (20 K * 2) = 15 + 40
Receipts (week 4) = 60] = 72.
Q LT = 1
Lot size: Multiples of 30
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
13
20
20
Scheduled receipts
Projected on hand
15
15
15
15
2
12
22
22
22
Net requirements
18
8
Planned-order receipts
30
30
Planned-order releases
30
30
Gross Requirements (week 3) = Planned-Order Releases of 13 K * 1 = 13.
Gross Requirements (week 4) = Planned-Order Releases of 20 K * 1 = 20.