CPIM Detailed Scheduling and Planning (MRP & Capacity) 2 — Questions and Answers
Question 1: What is 'safety time' in MRP, and how does it differ from safety stock?
- Safety time adds extra quantity; safety stock adds extra lead time
- Safety time adds extra lead time offset; safety stock adds extra inventory quantity (Correct answer)
- They are identical concepts with different names
- Safety time is used for purchased items; safety stock for manufactured items
Correct answer: Safety time adds extra lead time offset; safety stock adds extra inventory quantity
Safety time offsets the planned receipt date earlier than needed (adding lead time buffer), while safety stock adds a quantity buffer to protect against demand variability.
Question 2: Which lot-sizing rule minimizes total of ordering and carrying costs by evaluating period-by-period combinations?
- Fixed order quantity
- Period order quantity
- Part period balancing (Correct answer)
- Lot-for-lot
Correct answer: Part period balancing
Part period balancing combines periods until accumulated carrying cost approximates the ordering cost, balancing the two types of costs.
Question 3: In manufacturing, 'routing' provides which key information for planning?
- The list of materials needed to make a product
- The sequence of operations, work centers, and time standards for producing an item (Correct answer)
- The customer delivery schedule for finished goods
- The supplier list and lead times for raw materials
Correct answer: The sequence of operations, work centers, and time standards for producing an item
A routing defines each operation in the production process, the work center where it is performed, and the setup and run time standards used for scheduling and capacity planning.
Question 4: What is 'queue time' in a manufacturing routing?
- Time a job waits in front of a work center before processing begins (Correct answer)
- Time spent actually performing the operation
- Time to move a job between work centers
- Time to set up equipment before running a job
Correct answer: Time a job waits in front of a work center before processing begins
Queue time is the waiting time a job experiences in front of a work center and is often the largest component of manufacturing lead time.
Question 5: Which scheduling method assigns jobs to work centers by starting from the due date and working backward?
- Forward scheduling
- Backward scheduling (Correct answer)
- Drum-buffer-rope scheduling
- Gantt chart scheduling
Correct answer: Backward scheduling
Backward scheduling starts from the required completion date and subtracts lead times to calculate the latest start dates for each operation.
Question 6: What is the purpose of 'firm planned orders' in MRP?
- To automatically release purchase orders to suppliers
- To fix a planned order so MRP will not automatically change its date or quantity (Correct answer)
- To commit inventory to a specific customer order
- To create a firm financial commitment in the accounting system
Correct answer: To fix a planned order so MRP will not automatically change its date or quantity
A firm planned order is manually frozen by the planner to prevent MRP's automatic rescheduling logic from changing it, useful when the planner has knowledge MRP lacks.
CPIM Detailed Scheduling and Planning (MRP & Capacity) 2
What is 'safety time' in MRP, and how does it differ from safety stock?