Concept explainers
a)
To construct: A product structure.
Introduction:
Product structure:
The product structure is a visual representation of the components needed for a product assembly and the sequence at which they must be developed. It will clearly depict the parents and children components at each level.
a)
Answer to Problem 13P
Product structure:
Explanation of Solution
Given information:
- 1000 20” fans due in week 7.
- Each fan is made of a housing assembly, two grills, fan assembly and an electrical unit.
- Housing assembly is made of frame, two supports, and a handle.
- Fan assembly is made up of a hub and five blades.
- Electrical unit consists of a motor, switch and a knob.
| Component | Lead time | On-hand inventory | Lot size |
|
| 20" Fan | 1 | 100 | ||
| Housing | 1 | 100 | ||
| Frame | 2 | |||
| Supports (2) | 1 | 50 | 100 | |
| Handle | 1 | 400 | 500 | |
| Grills (2) | 2 | 200 | 500 | |
| Fan assembly | 3 | 150 | ||
| Hub | 1 | |||
| Blades (5) | 2 | 100 | ||
| Electrical unit | 1 | |||
| Motor | 1 | |||
| Switch | 1 | 20 | 12 | |
| Knob | 1 | 25 | 200 in week 2 |
Product structure:
The product is a 20” fan. It is made of four components. Each fan is made of a housing assembly, two grills, fan assembly and an electrical unit. Housing assembly is made of frame, two supports, and a handle. Fan assembly is made up of a hub and five blades. Electrical unit consists of a motor, switch and a knob.
b)
To construct: A time-phased product structure.
Introduction:
Time-phased product structure:
The time-phased product structure will represent the product visually with the details of when each component must begin production. It should be done to ensure that all the components are on time.
b)
Answer to Problem 13P
Time-phased product structure:
Explanation of Solution
Given information:
- 1000 20” fans due in week 7.
- Each fan is made of a housing assembly, two grills, fan assembly and an electrical unit.
- Housing assembly is made of frame, two supports, and a handle.
- Fan assembly is made up of a hub and five blades.
- Electrical unit consists of a motor, switch and a knob.
| Component | Lead time | On-hand inventory | Lot size | Scheduled receipt |
| 20" Fan | 1 | 100 | ||
| Housing | 1 | 100 | ||
| Frame | 2 | |||
| Supports (2) | 1 | 50 | 100 | |
| Handle | 1 | 400 | 500 | |
| Grills (2) | 2 | 200 | 500 | |
| Fan assembly | 3 | 150 | ||
| Hub | 1 | |||
| Blades (5) | 2 | 100 | ||
| Electrical unit | 1 | |||
| Motor | 1 | |||
| Switch | 1 | 20 | 12 | |
| Knob | 1 | 25 | 200 in week 2 |
Time-phased product structure:
The end product is the fan which must be ready at week 7. All the other components must be completed on week 6. The components at the lower level must be completed first before proceeding to the higher levels. Each component at each level is begun depending on the lead time of the product.
The products are started in advance so that they are developed and ready on time so that the dependent parent will be ready to develop its product. The process is repeated until all the subassemblies are ready to make the final product.
c)
To develop: A net requirements plan.
Introduction:
Net requirements plan:
The net requirements plan is the plan which is established on the gross requirements plan formed by deducting the stock on and the scheduled receipts. If the total requirement is below the safety stock levels, a planned order is made based on the given lot sizing technique.
c)
Explanation of Solution
Given information:
- 1000 20” fans due in week 7.
- Each fan is made of a housing assembly, two grills, fan assembly and an electrical unit.
- Housing assembly is made of frame, two supports, and a handle.
- Fan assembly is made up of a hub and five blades.
- Electrical unit consists of a motor, switch and a knob.
| Component | Lead time | On-hand inventory | Lot size | Scheduled receipt |
| 20" Fan | 1 | 100 | ||
| Housing | 1 | 100 | ||
| Frame | 2 | |||
| Supports (2) | 1 | 50 | 100 | |
| Handle | 1 | 400 | 500 | |
| Grills (2) | 2 | 200 | 500 | |
| Fan assembly | 3 | 150 | ||
| Hub | 1 | |||
| Blades (5) | 2 | 100 | ||
| Electrical unit | 1 | |||
| Motor | 1 | |||
| Switch | 1 | 20 | 12 | |
| Knob | 1 | 25 | 200 in week 2 |
Net requirements plan:
20’’ Fan:
| Week | ||||||||||||
| 20" Fan | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 1,000 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (100) | 100 | |||||||||||
| Net requirement | 900 | |||||||||||
| Planned order receipt | 900 | |||||||||||
| Planned order release | 900 | |||||||||||
Week 7:
The gross requirement is 1,000 (1 assembly). The on hand inventory is 100. Hence, the net requirement is 900. The lead time is 1 week. Therefore, the planned order release will be 900 in week 6 which will be the planned order receipt in week 7.
Housing:
| Week | ||||||||||||
| Housing | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 900 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (100) | 100 | |||||||||||
| Net requirement | 800 | |||||||||||
| Planned order receipt | 800 | |||||||||||
| Planned order release | 800 | |||||||||||
Week 6:
The gross requirement is 900 (1 assembly) derived from the planned order release of 20” fan. The on hand inventory is 100. Hence, the net requirement is 800. The lead time is 1 week. Therefore, the planned order release will be 800 in week 5 which will be the planned order receipt in week 6.
Grills:
| Week | ||||||||||||
| Grills | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 1,800 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (200) | 200 | 400 | ||||||||||
| Net requirement | 1,600 | |||||||||||
| Planned order receipt | 2,000 | |||||||||||
| Planned order release | 2,000 | |||||||||||
Week 6:
The gross requirement is 1,800 (2 assembly) derived from the planned order release of 20” fan. The on hand inventory is 200. Hence, the net requirement is 1,600. The lead time is 2 weeks. Therefore, the planned order release will be 2,000 (Lot Size = 500) in week 4 which will be the planned order receipt in week 6. The excess inventory will be available at week 7.
Fan assembly:
| Week | ||||||||||||
| Fan assembly | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 900 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (150) | 150 | |||||||||||
| Net requirement | 750 | |||||||||||
| Planned order receipt | 750 | |||||||||||
| Planned order release | 750 | |||||||||||
Week 6:
The gross requirement is 900 (1 assembly) derived from the planned order release of 20” fan. The on hand inventory is 150. Hence, the net requirement is 750. The lead time is 2 weeks. Therefore, the planned order release will be 750 in week 4 which will be the planned order receipt in week 6.
Electrical unit:
| Electrical Unit | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 900 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (0) | 0 | |||||||||||
| Net requirement | 900 | |||||||||||
| Planned order receipt | 900 | |||||||||||
| Planned order release | 900 |
Week 6:
The gross requirement is 900 (1 assembly) derived from the planned order release of 20” fan. The on hand inventory is 0. Hence, the net requirement is 900. The lead time is 1 week. Therefore, the planned order release will be 900 in week 5 which will be the planned order receipt in week 6.
Frame:
| Frame | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 800 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (0) | 0 | |||||||||||
| Net requirement | 800 | |||||||||||
| Planned order receipt | 800 | |||||||||||
| Planned order release | 800 |
Week 5:
The gross requirement is 800 (1 assembly) derived from the planned order release of Housing. The on hand inventory is 0. Hence, the net requirement is 800. The lead time is 2 weeks. Therefore, the planned order release will be 800 in week 3 which will be the planned order receipt in week 5.
Supports:
| Week | ||||||||||||
| Supports | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 1,600 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (50) | 50 | |||||||||||
| Net requirement | 1,550 | |||||||||||
| Planned order receipt | 1,600 | |||||||||||
| Planned order release | 1,600 | |||||||||||
Week 5:
The gross requirement is 1,600 (2 assembly) derived from the planned order release of Housing. The on hand inventory is 50. Hence, the net requirement is 1,550. The lead time is 1 week. Therefore, the planned order release will be 1,600 (Lot size = 100) in week 4 which will be the planned order receipt in week 5. The excess inventory is available at week 6.
Handle:
| Week | ||||||||||||
| Handle | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 800 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (400) | 400 | 100 | ||||||||||
| Net requirement | 400 | |||||||||||
| Planned order receipt | 500 | |||||||||||
| Planned order release | 500 | |||||||||||
Week 5:
The gross requirement is 800 (1 assembly) derived from the planned order release of Housing. The on hand inventory is 400. Hence, the net requirement is 400. The lead time is 1 week. Therefore, the planned order release will be 500 (Lot size = 500) in week 4 which will be the planned order receipt in week 5. The excess inventory is available at week 6.
Hub:
| Week | ||||||||||||
| Hub | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 750 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (0) | 0 | |||||||||||
| Net requirement | 750 | |||||||||||
| Planned order receipt | 750 | |||||||||||
| Planned order release | 750 | |||||||||||
Week 3:
The gross requirement is 750 (1 assembly) derived from the planned order release of fan assembly. The on hand inventory is 0. Hence, the net requirement is 750. The lead time is 1 week. Therefore, the planned order release will be 750 in week 2 which will be the planned order receipt in week 3.
Blades:
| Week | ||||||||||||
| Blades | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 3,750 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (0) | 0 | 50 | ||||||||||
| Net requirement | 3,750 | |||||||||||
| Planned order receipt | 3,800 | |||||||||||
| Planned order release | 3,800 | |||||||||||
Week 3:
The gross requirement is 3,750 (5 assembly) derived from the planned order release of fan assembly. The on hand inventory is 0. Hence, the net requirement is 3,750. The lead time is 2 weeks. Therefore, the planned order release will be 3,800 (Lot size = 100) in week 1 which will be the planned order receipt in week 3. The excess inventory will be available at week 4.
Motor:
| Week | ||||||||||||
| Motor | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 900 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (0) | 0 | |||||||||||
| Net requirement | 900 | |||||||||||
| Planned order receipt | 900 | |||||||||||
| Planned order release | 900 | |||||||||||
Week 5:
The gross requirement is 900 (1 assembly) derived from the planned order release of Electrical unit. The on hand inventory is 0. Hence, the net requirement is 900. The lead time is 1 week. Therefore, the planned order release will be 900 in week 4 which will be the planned order receipt in week 5.
Switch:
| Week | ||||||||||||
| Switch | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 900 | |||||||||||
| Scheduled receipt | ||||||||||||
| On hand (20) | 20 | 8 | ||||||||||
| Net requirement | 880 | |||||||||||
| Planned order receipt | 888 | |||||||||||
| Planned order release | 888 | |||||||||||
Week 5:
The gross requirement is 900 (1 assembly) derived from the planned order release of Electrical unit. The on hand inventory is 20. Hence, the net requirement is 880. The lead time is 1 week. Therefore, the planned order release will be 888 (Lot Size = 12) in week 4 which will be the planned order receipt in week 5. The excess inventory will be available at week 6.
Knob:
| Week | ||||||||||||
| Knob | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| Gross requirements | 900 | |||||||||||
| Scheduled receipt | 200 | |||||||||||
| On hand (0) | 200 | 200 | 200 | |||||||||
| Net requirement | 700 | |||||||||||
| Planned order receipt | 700 | |||||||||||
| Planned order release | 700 | |||||||||||
Week 2:
There is a scheduled receipt of 200 which can be used as inventory.
Week 5:
The gross requirement is 900 (1 assembly) derived from the planned order release of Electrical unit. The on hand inventory is 0. But, there is a scheduled receipt of 200. Hence, the net requirement is 7000. The lead time is 1 week. Therefore, the planned order release will be 700 in week 4 which will be the planned order receipt in week 5.
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Chapter 14 Solutions
Principles Of Operations Management
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