How is the net requirement of A in week 4 found, and what is it?

50 units, since stock is ignored

How is the gross requirement of component B obtained?

2 x planned order releases of A (since each A needs 2 B)

2 x planned order receipts of B

Practice · 8 marks

MRP explosion with lot-for-lot ordering

Short answer

MRP for A: release 30 units in week 3 and 80 in week 5. For B: release 150 units in week 3 (lead time 2 weeks). Lot-for-lot ordering used.

Product A is assembled from 2 units of component B. The master production schedule requires 50 units of A in week 4 and 80 units of A in week 6. Data: A has on-hand stock of 20 units, lead time 1 week; B has on-hand stock of 40 units, a scheduled receipt of 30 units in week 2, and lead time 2 weeks. Use lot-for-lot ordering. Prepare the MRP records for A and B for weeks 1 to 8 and find the planned order releases.

Method

For each item: Net requirement = Gross requirement - (projected on hand + scheduled receipt). Planned order receipt = net requirement (lot-for-lot). The planned order release is the receipt moved earlier by the lead time. The releases of A give the gross requirement of B: $2 \times$ A releases.

Item A (LT = 1 week, on hand 20)

Week	1	2	3	4	5	6
Gross requirement	0	0	0	50	0	80
Scheduled receipts	0	0	0	0	0	0
Projected on hand	20	20	20	0	0	0
Net requirement	0	0	0	30	0	80
Planned order receipt	0	0	0	30	0	80
Planned order release	0	0	30	0	80	0

Week 4: 50 needed, 20 in stock, so 30 to be produced and released in week 3. Week 6: 80 needed, stock is zero, release in week 5.

Item B (LT = 2 weeks, on hand 40, receipt of 30 in week 2)

Gross requirement of B $= 2 \times 30 = 60$ in week 3 and $2 \times 80 = 160$ in week 5.

Week	1	2	3	4	5
Gross requirement	0	0	60	0	160
Scheduled receipts	0	30	0	0	0
Projected on hand	40	70	10	10	0
Net requirement	0	0	0	0	150
Planned order receipt	0	0	0	0	150
Planned order release	0	0	150	0	0

Week 3: available 70 against need 60, leaving 10. Week 5: need 160, stock 10, so net 150; the release is moved two weeks earlier to week 3.

Answer: Release 30 units of A in week 3 and 80 in week 5; release 150 units of B in week 3.

✓ Answer checked by Claude Opus 5.5 (high effort)

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MRP explosion with lot-for-lot ordering

Method

Item A (LT = 1 week, on hand 20)

Item B (LT = 2 weeks, on hand 40, receipt of 30 in week 2)

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