Material Requirements Planning Suggested
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Harvard University *
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4204
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Industrial Engineering
Date
Apr 3, 2024
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12
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1 ISE 4204 –
Production Planning and Inventory Control Material Requirements Planning Suggested Problems 0.
Friendly reminder to practice the shovel example from class. 1.
The product structure diagram is shown on the following page for a telephone produced by Montgomery Phone. The product structure diagram includes the components of the telephone, the quantity of each component required for each phone, and the lead time for each part. The production planning department has developed the forecast by period for the phone as follows: (25 points) Period Forecast 1.
600 2.
1000 3.
1200 4.
1850 5.
1550 6.
2050 7.
1800 The on-hand inventory is: Telephone 1900 Hand Set Assembly 950 Base Assembly 850 Hand Set Cord 1050 Tapping Screw 3800 The scheduled receipts are: Hand Set Assembly 650 in time period 1 Base Assembly 350 in time period 1 Tapping Screw 5000 in time period 1 Given this information, develop the planned order releases for the Telephone, Hand Set Assembly, Base Assembly, Hand Set Cord, and Tapping Screw. All orders are planned using lot-for-lot, except for the Tapping Screw, which has a lot size of 5000.
2
3 Telephone Lead Time = 1 wk Lot-for-Lot Time Period 1 2 3 4 5 6 7 Gross Requirements Scheduled Receipts Projected On-hand Inv Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv Hand Set Assembly Lead Time = 1 wk Lot-for-Lot Time Period 1 2 3 4 5 6 7 Gross Requirements Scheduled Receipts Projected On-hand Inv Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv Base Assembly Lead Time = 1 wk Lot-for-Lot Time Period 1 2 3 4 5 6 7 Gross Requirements Scheduled Receipts Projected On-hand Inv Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv
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4 Hand Set Cord Lead Time = 2 wks Lot-for-Lot Time Period 1 2 3 4 5 6 7 Gross Requirements Scheduled Receipts Projected On-hand Inv Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv Tapping Screw Lead Time = 1 week Lot Size = 5000 Time Period 1 2 3 4 5 6 7 Gross Requirements Scheduled Receipts Projected On-hand Inv Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv
5 2.
Based on Problem 8.49 in the text. Assume the time phased net requirements (in thousands) for a component are provided for the next 10 weeks. Assume the setup costs are $200, and the holding costs are $3.25 per thousand units per week. Week 1 2 3 4 5 6 7 8 9 10 Time-
phased net reqmts 22 34 32 12 8 44 54 16 76 30 Answer the following questions: (25 points) a)
What planned order releases do you obtain using the lot-for-lot approach? b)
What planned order releases do you obtain using the EOQ formula? c)
What planned order releases do you obtain using the Silver-Meal heuristic? d)
What planned order releases do you obtain using the Least Unit Cost heuristic? 3.
Using a table format, compare the setup costs and holding costs and the sum of the setup and holding costs over the 10 time periods for each of the five approaches in Problem 2. Which is the preferred approach? (10 points) The table will appear as follows: Approach Setup Costs Holding Costs Setup and Holding Costs Lot-for-Lot Etc. Also, which is the preferred approach?
6 4. A partially completed MRP form for inventory item L56 Nails, with a lead time of 1 time period, is given below. Complete the form using the following three scenarios: (20 points) a)
Lot-for-Lot b)
Lot Size = 100 c)
Lot-for-Lot and a Safety Stock of 20 d)
Lot-for-Lot with a Yield of 90% a)
Lot-for-Lot Time Period 1 2 3 4 5 6 7 8 Gross Requirements 60 45 70 65 85 95 55 70 Scheduled Receipts 70 Projected On-
hand Inv 85 Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv b)
Lot Size = 100 Time Period 1 2 3 4 5 6 7 8 Gross Requirements 60 45 70 65 85 95 55 70 Scheduled Receipts 70 Projected On-
hand Inv 85 Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv
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7 c)
Lot-for-Lot and a Safety Stock of 20 Time Period 1 2 3 4 5 6 7 8 Gross Requirements 60 45 70 65 85 95 55 70 Scheduled Receipts 70 Projected On-
hand Inv 85 Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv d)
Lot-for-Lot and a Yield of 90% Time Period 1 2 3 4 5 6 7 8 Gross Requirements 60 45 70 65 85 95 55 70 Scheduled Receipts 70 Projected On-
hand Inv 85 Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv
8 5. For the telephone problem (#1), let’s assume that the planned order releases and planned order deliveries are shown below for weeks 10 –
14 for the Hand Set Assembly and the Base Assembly. Let’s assume that the hand set assembly and the base assembly are assembled manually and then tested using automated testing equipment. Each Hand Set Assembly requires 3.5 hours of manual assembly time and 0.5 hours of automated testing time. Each Base Assembly requires 1.50 hours of manual assembly time and 0.25 hours of automated testing time. (20 points) a)
Determine the load profile (in hours) by time period for the manual assembly group and the automated testing machine. b) Assume an assembly worker works 40 hours per week for a single shift. The plant is currently operating 2 shifts. Assume each testing station is available for both shifts and can be used for testing either part. How many workers are required each week? How many test stations are required each week? Hand Set Assembly Time Period 10 11 12 13 14 15 Planned Order Releases 1200 1350 1000 950 1150 Planned Order Deliveries 1200 1350 1000 950 1150 Base Assembly Time Period 10 11 12 13 14 15 Planned Order Releases 1050 1150 1000 950 1150 Planned Order Deliveries 1050 1150 1000 950 1150
9 6. Product L is assembled from one part M and two part N’s. Each item requires one or more operations, as indicated by the circles in the product structure diagram. For example, some raw materials are processed through operation 10 (machining) and operation 20 (heat treat) before becoming Part N. Some raw materials are processed through operation 30 (machining) before becoming Part M. Then one part M and 2 part Ns are assembled in operation 40 (assembly) to become End Item L. Assume lead time for planning purposes is 1 week for all parts. Given the following Master Production Schedule and Material Requirements Plan, develop a load profile chart for each of the three work centers for the first 6 weeks. (25 points) Master Production Schedule Period 1 2 3 4 5 6 7 Product L 150 200 150 250 175 Routing and Work Standard File Operation Part Work Center Standard Time per unit (hr) 10 N Machining 0.75 20 N Heat Treat 2.00 30 M Machining 1.25 40 L Assembly 0.50
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10 L N (2 each) opn 20 opn 10 opn 30 opn 40 M (1 each)
11 ISE 5044 –
Production Systems Analysis Material Requirements Planning Homework Part L Lead Time = 1 time period Time Period 1 2 3 4 5 6 7 8 Gross Requirements 150 200 150 250 175 Scheduled Receipts Projected On-hand Inv 0 Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Del Projected Ending Inv 0 Part M Lead Time = 1 time period Time Period 1 2 3 4 5 6 7 8 Gross Requirements Scheduled Receipts Projected On-hand Inv 25 Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Del Projected Ending Inv 25 Part N Lead Time = 1 time period Time Period 1 2 3 4 5 6 7 8 Gross Requirements Scheduled Receipts Projected On-hand Inv 50 Net Requirements Time Phased Reqmts Planned Order Releases Planned Order Deliveries Projected Ending Inv 50
12 Loads Created by Each Part Part Opn Work Center Hrs/Unit 1 2 3 4 5 6 7 Load Profiles for Work Centers (in hours each week) Work Center 1 2 3 4 5 6 7 Heat Treat Machining Assembly
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