Chapter13ExampleProblems_overheads

1、Chapter 13: Material Requirements PlanningApplication 1: Calculating an MRP RecordItem H10-A is a produced item (not purchased) with an order quantity of 80 units. Complete the rest of its MRP record using the fixed order quantity (FOQ) rule.Item: H10-A Lot Size: FOQ=80 unitsDescription: Chair seat

2、assembly Lead Time: 4 weeksWeek31323334353637383940Gross requirements60354560Scheduled receipts8020Projected on-hand inventory 2010040404040554040Planned receipts008080Planned order releases8080.Material Requirements PlanningApplication 3: MRP Record using the lot-for-lot (L4L) RuleRevise the H10-A

3、record using the lot-for-lot (L4L) Rule.Item: H10-A Lot Size: L4LDescription: Chair seat assembly Lead Time: 4 weeksWeek31323334353637383940Gross requirements60354560Scheduled receipts8020Projected on-hand inventory 20100404040405500Planned receipts004060Planned order releases4060Material Requiremen

4、ts Planning Application 4: Material Requirements Plan for Single Product Case.A firm makes a product (Item A) from three components (Items B, C, and D). The latest MPS for product A calls for completion of a 250-unit order in week 8, and its lead time is 2 weeks. The master schedule and bill of mate

5、rial for Product A are given below.Item: End Item A Lead Time: 2 wks.Week12345678MPS Quantity250MPS Start250a.Develop a material requirements plan for items B, C, and D, given the following inventory data. Blank MRP records are also provided. ITEMData CategoryBCDLot-sizing ruleL4LFOQ=1000L4LLead tim

6、e2 weeks1 week3 weeksScheduled receiptsNone1000(week 1)NoneBeginning inventory02000Application SupplementItem: End Item A Lead Time: 2 wks.Week12345678MPS Quantity250MPS Start250Item: BLot size: L4LLead Time: 2Week12345678Gross Requirements 500250Scheduled Receipts 00Projected On-hand Inven. 00Net R

7、equirements500250Planned Order Receipts500250Planned Order Releases500250Item: CLot size: FOQ = 1000Lead Time: 1Week12345678Gross Requirements1000 500250Scheduled Receipts100000Proj. On-hand Inv. 2001200200200200700700450450Net Requirements03000Planned Order Receipts01000Planned Order Releases1000 I

8、tem: DLot size: L4LLead Time: 3Week12345678Gross Requirements 500 Scheduled Receipts 0Proj. On-hand Inven. 0 Net Requirements500Planned Order Receipts 500 Planned Order Releases 500 Explanation of the Above TableYour Question: What determines the order time in B and C of the forks that are not on we

9、ek 6? How come, for example, in B you are ordering 500 in week 3 for the right fork when it only needs 250? and in C when 1000 is ordered in week one for the right fork when it only needs 500?Answer: You must follow the decisions down the BOM for each fork. They are color coded, as above. Basically,

10、 you end up multiplying requirements for the level above, by the number required at the next level. As a result, your requirements keep growing with each level down the BOM that you go. BLUE = decisions about materials required for the leftmost fork of the bill of materialsPURPLE = decisions about m

11、aterials required for middle forkGREEN = decisions about materials required for right forkHere is a step-by-step explanation of the color-coded table:RIGHT FORKWell start with the right fork first (GREEN NUMBERS). Luckily, no other fork requires any Ds, so we only have one thing to do, and then were

12、 done with the table for D. Assembling one A requires us to have 2 Ds available in week 6, so for 250 As, well need to make sure we have 500 Ds available in week 6. Because we have zero scheduled receipts of D and zero projected on hand inventory for D, we have a net requirement of 500 Ds. We are or

13、dering Lot-for-Lot, meaning that we want to have 500 Ds arrive in our factory at the beginning of Week 6. In order to have this, well have to place an order for materials (500 Ds) at the beginning of Week 3 (3 weeks earlier, due to the 3 week Lead Time).Next, building each D requires one B. Thus for

14、 500 Ds to be started in week 3, we need to make sure that 500 Bs are available in Week 3. So, you must go up to the table for B, and input a Gross Requirements for B during week 3 of 500 units. Since were not expecting any receipts and have no inventory, this leads to a Net Requirement of 500 Bs, a

15、nd again were using Lot-for-Lot, so we need 500 to arrive during week 3, and thus need to place an order for 500 during week 1.Finally, building a B requires 2 Cs to be available. Since well need 500 Bs in Week 1, wee need to have 1000 Cs available. Luckily, we have a scheduled receipt of 1000 Cs in

16、 week one plus 200 Cs in inventory on-hand, so we are covered, and do not need to place any additional orders for this fork.LEFT FORKNext, the left fork (BLUE NUMBERS). Assembling one A requires us to have one B available in week 6 (meaning, for 250 As well need to have 250 Bs available at the start

17、 of week 6). So, our Gross Requirements for B during Week 6 is 250. Since were not receiving any and not holding any in inventory, well place an order in Week 4 for 250 Bs, due to the 2 week Lead Time.Moving down the left fork, we need 2 Cs to assemble each B, so our gross requirement of Cs will be

18、250 * 2 = 500 Cs during Week 4. During Week 4, we will have 200 Cs projected to be onhand inventory, so we will only have a Net Requirement of 300 Cs. Since we are ordering fixed order quantities of 1000, we will plan to receive an order of 1000 Cs during Week 4, and due to the one week Lead Time, w

19、ell place the order for 1000 Cs during Week 3.MIDDLE FORKFinally, the middle, and easiest/shortest, fork (PURPLE NUMBERS). For each A, we need one C. Thus, for 250 As during Week 6, well need to have 250 Cs available. So, our gross requirement will be 250 Cs in Week 6. We will have 700 Cs in on-hand inventory left over from our order that we receive in w