Chapter 12 – MRP and ERP
G & G(2) LT = 2
Lot size: Multiples of 80
Beg.
Inv.
1
2
3
4
5
6
7
Gross requirements
140
30
Scheduled receipts
Projected on hand
15
15
15
15
15
35
5
5
Net requirements
125
Planned-order receipts
160
Planned-order releases
160
Notes:
Gross Requirements (week 4) = Planned-Order Releases of 70 C * 2 = 140.
Gross Requirements (week 5) = Planned-Order Releases of 30 Robots * 1 = 30.
POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4
POH4 = [15 + 0 – 0] + 0 = 15.
POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5
POH5 = [15 + 160 – 140] + 0 = 35.
POH6 = [POH5 + Planned-Order Receipts5 – Gross Requirements5] + Scheduled Receipts6
POH6 = [35 + 0 – 30] + 0 = 5.
11. a. Given:
Refer back to Solved Problem 3. On hand balances: N = 100 and E = 0. Scheduled receipts: I
= 40 and V = 10 at the beginning of week 3. 120 E are needed at the start of week 5. We have
the product structure tree shown below. Determine material requirements plans for E, I, N,
and V using lot-for-lot ordering as was used in Solved Problem 3:
M(3)
I(2)
E
V
Chapter 12 – MRP and ERP
I(2) LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
240
Scheduled receipts
40
Projected on hand
0
0
0
40
40
0
0
0
0
Net requirements
200
Planned-order receipts
200
Planned-order releases
200
Notes:
Gross Requirements (week 4) = Planned-Order Releases of 120 E * 2 = 240.
Scheduled receipts
Projected on hand
100
100
100
Planned order receipts
700
Planned order releases
700
Gross requirements
200
Scheduled receipts
Projected on hand
Chapter 12 – MRP and ERP
b. Given:
Assume that on hand balances and scheduled receipts remain the same as in part a. On hand
balances: N = 100 and E = 0. Scheduled receipts: I = 40 and V = 10 at the beginning of week
3.
New information: 100 E are needed at the start of week 5 and 55 are needed at the start of
week 7. Determine the material requirements plans for E, I, N, and V using lot-for-lot
ordering for E and I, and multiples of these order sizes: N = 800 and V = 200.
Master
Schedule for:
E
1
2
3
4
5
6
7
8
100
55
E LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
100
55
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
100
55
Planned-order receipts
100
55
Planned-order releases
100
55
M(3)
I(2)
R(2)
P
N(4)
V
E
Gross requirements
200
110
Scheduled receipts
Projected on hand
40
40
Chapter 12 – MRP and ERP
12–34
Education.
N(4) LT = 2
Lot size: Multiples of 800
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
640
440
Scheduled receipts
Projected on hand
100
100
100
100
260
260
620
620
620
Net requirements
540
180
Planned order receipts
800
800
Planned order releases
800
800
POH6 = [POH5 + Planned-Order Receipts5 – Gross Requirements5] + Scheduled Receipts6
POH6 = [260 + 800 – 440] + 0 = 620.
V LT = 2
Lot size: Multiples of 200
Beg.
Inv.
1
2
3
4
5
6
7
8
Gross requirements
160
110
Scheduled receipts
10
Projected on hand
0
0
0
10
50
50
140
140
140
Net requirements
150
60
Planned order receipts
200
200
Planned order releases
200
200
Notes:
Gross Requirements (week 3) = Planned-Order Releases of 160 I * 1 = 160.
Gross Requirements (week 5) = Planned-Order Releases of 110 I * 1 = 110.
POH3 = [POH2 + Planned-Order Receipts2 – Gross Requirements2] + Scheduled Receipts3
12–36
c. continued
Master
Schedule for:
E
2
3
4
5
6
7
8
9
100
55
100
E LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
2
3
4
5
6
7
8
9
Gross requirements
100
55
100
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
100
55
100
Planned-order receipts
100
55
100
Planned-order releases
100
55
100
I(2) LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
2
3
4
5
6
7
8
9
Gross requirements
200
110
200
Scheduled receipts
40
Projected on hand
0
0
40
40
0
0
0
0
0
Net requirements
160
110
200
Planned-order receipts
160
110
200
Planned-order releases
160
110
200
Notes:
POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5
POH5 = [40 + 160 – 200] + 0 = 0.
POH9 = [POH8 + Planned-Order Receipts8 – Gross Requirements8] + Scheduled Receipts9
POH9 = [0 + 200 – 200] + 0 = 0.
Chapter 12 – MRP and ERP
12–37
N(4) LT = 2
Lot size: Multiples of 800
Beg.
Inv.
2
3
4
5
6
7
8
9
Gross requirements
640
440
800
Scheduled receipts
800
Projected on hand
100
100
900
260
260
620
620
620
620
Net requirements
180
180
Planned order receipts
800
800
Planned order releases
800
800
Gross Requirements (week 5) = Planned-Order Releases of 110 I * 4 = 440.
Gross Requirements (week 7) = Planned-Order Releases of 200 I * 4 = 800.
POH3 = [POH2 + Planned-Order Receipts2 – Gross Requirements2] + Scheduled Receipts3
POH3 = [100 + 0 – 0] + 800 = 900.
POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4
V LT = 2
Lot size: Multiples of 200
Beg.
Inv.
2
3
4
5
6
7
8
9
Gross requirements
160
110
200
Scheduled receipts
210
Projected on hand
0
0
210
50
50
140
140
140
140
Net requirements
60
60
Planned order receipts
200
200
Planned order releases
200
200
Notes:
Gross Requirements (week 3) = Planned-Order Releases of 160 I * 1 = 160.
Gross Requirements (week 5) = Planned-Order Releases of 110 I * 1 = 110.
Gross Requirements (week 7) = Planned-Order Releases of 200 I * 1 = 200.
POH3 = [POH2 + Planned-Order Receipts2 – Gross Requirements2] + Scheduled Receipts3
POH6 = [POH5 + Planned-Order Receipts5 – Gross Requirements5] + Scheduled Receipts6
POH6 = [50 + 200 – 110] + 0 = 140.
POH8 = [POH7 + Planned-Order Receipts7 – Gross Requirements7] + Scheduled Receipts8
POH8 = [140 + 200 – 200] + 0 = 140.
Chapter 12 – MRP and ERP
12–38
Case 2 Given:
Refer back to the previous update. It is now the start of week 4. Assume that all orders were
released and received as planned in weeks 2 and 3.
Notes:
a. We will drop 2 weeks (weeks 2 & 3) from the material plans and add 2 weeks at the end of
each plan.
b. Any Planned-Order Releases from weeks 2 & 3 must now show up as Scheduled Receipts:
beginning inventory balances in week 4.
Remember: Scheduled receipts increase inventory while gross requirements decrease
inventory.
Ending Inventory = Beginning Inventory + Scheduled Receipts – Gross Requirements
Item E
Week 2
Week 3
Ending Inventory
0 + 0 – 0 = 0
0 + 0 – 0 = 0
Item I
Week 2
Week 3
Ending Inventory
0 + 0 – 0 = 0
0 + 40 – 0 = 40
Item N
Week 2
Week 3
Ending Inventory
100 + 0 – 0 = 100
100 + 800 – 640 = 260
Item V
Week 2
Week 3
Ending Inventory
0 + 0 – 0 = 0
0 + 210 – 160 = 50
M(3)
I(2)
R(2)
P
N(4)
V
E
Chapter 12 – MRP and ERP
12–39
Master
Schedule for:
E
4
5
6
7
8
9
10
11
100
55
100
E LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
4
5
6
7
8
9
10
11
Gross requirements
100
55
100
Scheduled receipts
Projected on hand
0
0
0
0
0
0
0
0
0
Net requirements
100
55
100
Planned-order receipts
100
55
100
Planned-order releases
100
55
100
I(2) LT = 1
Lot size: Lot-for-Lot
Beg.
Inv.
4
5
6
7
8
9
10
11
Gross requirements
200
110
200
Scheduled receipts
160
Projected on hand
40
200
0
0
0
0
0
0
0
Net requirements
110
200
Planned-order receipts
110
200
Planned-order releases
110
200
Notes:
POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5
POH5 = [200 + 0 – 200] + 0 = 0.
Chapter 12 – MRP and ERP
12–40
N(4) LT = 2
Lot size: Multiples of 800
Beg.
Inv.
4
5
6
7
8
9
10
11
Gross requirements
440
800
Scheduled receipts
800
Projected on hand
260
260
1060
620
620
620
620
620
620
Net requirements
180
Planned order receipts
800
Planned order releases
800
V LT = 2
Lot size: Multiples of 200
Beg.
Inv.
4
5
6
7
8
9
10
11
Gross requirements
110
200
Scheduled receipts
200
Projected on hand
50
50
250
140
140
140
140
140
140
Net requirements
60
Planned order receipts
200
Planned order releases
200
POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5
POH5 = [50 + 0 – 0] + 200 = 250.
POH6 = [POH5 + Planned-Order Receipts5 – Gross Requirements5] + Scheduled Receipts6
POH6 = [250 + 0 – 110] + 0 = 140.