Problems 1. Here are the parts list and the lead time for product TT. | Component/Subassembly | Number Required | Lead time | Product TT | | | Subassembly A | 2 | 1 week | | Component B | 1 | 2 weeks | | Subassembly A | | | | Component B | 3 | 2 weeks | | Component C | 1 | 1 week | | Component D | 2 | 1 week |
The master schedule for product TT is: | Week Number | 1 | 2 | 3 | 4 | 5 | 6 | | Quantity | 0 | 0 | 0 | 25 | 50 | 75 |
- Construct the product-structure tree for product TT.
- Determine the quantity of each subassembly and component that will
be required.
- Construct the time-phased plan for each subassembly and component in
the style of Figure 15-9 in your textbook; four of them will be required.
See next page.
2. Use the data in Problem 1 to solve this problem. During the fourth week,
an equipment breakdown delayed the production of component D for one week.
Thus, the 300 units which were to go into production in the fourth week
and be received in the fifth week must be postponed to the fifth and sixth
weeks. - Construct a new master schedule for the fourth and subsequent weeks.
- Construct new time-phased plans for each subassembly and component
for the fourth and subsequent weeks.
3. Here is the usage schedule for component K. Period 1 2 3 4 5 6
Quantity 60 50 80 70 30 50 It costs $500 to set up the equipment to produce K. and it costs $2 to
store one unit of K for one period. - What is the cumulative demand schedule?
- What is the economic part-period (EPP)?
- What is the lot size (based on the EPP)?
Master | Week | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Schedule | Quantity | | | | | | | | |
| | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Gross requirements | | | | | | | | | Scheduled receipts | | | | | | | | | Projected on hand | | | | | | | | | Net requirements | | | | | | | | | Planned-order receipts | | | | | | | | | Planned-order releases | | | | | | | | |
| | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Gross requirements | | | | | | | | | Scheduled receipts | | | | | | | | | Projected on hand | | | | | | | | | Net requirements | | | | | | | | | Planned-order receipts | | | | | | | | | Planned-order releases | | | | | | | | |
| | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Gross requirements | | | | | | | | | Scheduled receipts | | | | | | | | | Projected on hand | | | | | | | | | Net requirements | | | | | | | | | Planned-order receipts | | | | | | | | | Planned-order releases | | | | | | | | |
| | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8v | Gross requirements | | | | | | | | | Scheduled receipts | | | | | | | | | Projected on hand | | | | | | | | | Net requirements | | | | | | | | | Planned-order receipts | | | | | | | | | Planned-order releases | | | | | | | | |
Solutions 1. a. TT b. The master schedule calls for 150 units of product TT. | Subassembly/component | | Quantity | | | Product TT Subassembly A Component B Subassembly A Component B Component C Component D | | 300 (150 x 2) 150 900 (300 x 3) 300 600 (300 x 2) |
The list may be condensed by combining the quantities for Component B: | Subassembly/component | | Quantity | | | Product TT Subassembly A Component B Component C Component D | | 300 1050 300 600 |
c. Subassemby A LT = 1 wk. | 1 | 2 | 3 | 4 | 5 | 6 | Gross requirements | | | | 50 | 100 | 150 | Scheduled receipts | | | | | | | Projected on hand | | | | | | | Net requirements | | | | 50 | 100 | 150 | Planned-order receipts | | | | 50 | 100 | 150 | Planned-order releases | | | 50 | 100 | 150 | |
Component B LT = 2 wk. | 1 | 2 | 3 | 4 | 5 | 6 | Gross requirements | | | 150 | 325 | 500 | 75 | Scheduled receipts | | | | | | | Projected on hand | 100 | 100 | 100 | | | | Net requirements | | | 50 | 325 | 500 | 75 | Planned-order receipts | | | 50 | 325 | 500 | 75 | Planned-order releases | 50 | 325 | 500 | 75 | | |
Component C LT = 1 wk. | 1 | 2 | 3 | 4 | 5 | 6 | Gross requirements | | | 50 | 100 | 150 | | Scheduled receipts | | | | | | | Projected on hand | | | | | | | Net requirements | | | 50 | 100 | 150 | | Planned-order receipts | | | 50 | 100 | 150 | | Planned-order releases | | 50 | 100 | 150 | | |
Component D LT = 1 wk. | 1 | 2 | 3 | 4 | 5 | 6 | Gross requirements | | | 100 | 200 | 300 | | Scheduled receipts | | | | | | | Projected on hand | | | | | | | Net requirements | | | 100 | 200 | 300 | | Planned-order receipts | | | 100 | 200 | 300 | | Planned-order releases | | 100 | 200 | 300 | | |
2. a. The delay in producing component D will cause a one-week delay in producing subassembly A and the last 75 units of product TT will be delayed one week beyond that time, for a total of two weeks. | | Week | 4 | 5 | 6 | 7 | 8 | | | Quantity | 25 | 50 | | | 75 |
b. | | Assembly A LT = 1 wk. | 4 | 5 | 6 | 7 | 8 | | | Gross requirements | 50 | 100 | | | 150 | | | Scheduled receipts | | | | | | | | Projected on hand | | | | | | | | Net requirements | 50 | 100 | | | 150 | | | Planned-order receipts | 50 | 100 | | | 150 | | | Planned-order releases | 100 | | 150 | | |
| | Component B LT = 2 wk. | 4 | 5 | 6 | 7 | 8 | | | Gross requirements | 325 | 50 | | 450 | 75 | | | Scheduled receipts | | | | | | | | Projected on hand | | | 450 | 450 | | | | Net requirements | 325 | 50 | | | 75 | | | Planned-order receipts | 325 | 50 | | | 75 | | | Planned-order releases | | | 75 | | |
| | Component C LT = 1 wk. | 4 | 5 | 6 | 7 | 8 | | | Gross requirements | 100 | | 150 | | | | | Scheduled receipts | | | | | | | | Projected on hand | | | | | | | | Net requirements | 100 | | 150 | | | | | Planned-order receipts | 100 | | 150 | | | | | Planned-order releases | | 150 | | | |
|
| Component D LT = 1 wk. | 4 | 5 | 6 | 7 | 8 | | | Gross requirements | 200 | | 300 | | | | | Scheduled receipts | | | | | | | | Projected on hand | | | | | | | | Net requirements | 200 | | 300 | | | | | Planned-order receipts | 200 | | 300 | | | | | Planned-order releases | | 200 | | | |
3. a. The cumulative usage schedule. | | Period | 1 | 2 | 3 | 4 | 5 | 6 | | | Quantity | 60 | 110 | 190 | 260 | 290 | 340 |
b. EPP = (Setup Cost)/(Unit Holding Cost) = 500/2 = 250.
c. Calculate cumulative part-periods based on the cumulative quantities.
| | Period | Lot size | Inventory | Periods carried | Part- periods | Cumulative Part-periods | | | 1 | 60 110 190 260 | 0 50 80 70 | 0 1 2 3 | 0 50 160 210 | 0 50 210* 420 |
*210 is closest to the EPP of 250; produce 190 units. The 190 units will satisfy the requirements of the first three periods. Repeat
the calculation
for the next three periods. | | Period | Lot size | Inventory | Periods carried | Part- periods | Cumulative Part-periods | | | 4 | 70 100 150 | 0 30 50 | 0 1 2 | 0 30 100 | 0 30 130 |
The final entry of 130 does not seem to be close to the EPP of 250. Obtain the requirements for component K for later weeks and continue the calculation | 