CPIM Detailed Scheduling 4 — Questions and Answers
Question 1: What is 'Operation Splitting' and why is it used in detailed scheduling?
- Dividing a work order across multiple time periods to reduce lead time (Correct answer)
- Combining multiple small orders into one large batch
- Assigning an operation to two different employees
- Breaking a routing into separate BOMs
Correct answer: Dividing a work order across multiple time periods to reduce lead time
Operation splitting divides a work order into smaller lots that can be run simultaneously on multiple machines, reducing total lead time.
Question 2: In MRP, what is the 'time fence' nearest to the current date that typically locks the schedule?
- Planning fence
- Demand time fence
- Frozen zone (firm planned horizon) (Correct answer)
- Action horizon
Correct answer: Frozen zone (firm planned horizon)
The frozen zone or firm planned horizon is the period closest to today where the master schedule is locked and changes require management approval to avoid disruption.
Question 3: Which of the following is a primary input to detailed capacity requirements planning (CRP)?
- Sales forecasts only
- Open work orders, planned orders, and routing data (Correct answer)
- Customer order backlog only
- Finished goods inventory levels
Correct answer: Open work orders, planned orders, and routing data
CRP uses planned and open work orders combined with routing information (operations, work centers, run times) to calculate detailed capacity needs.
Question 4: What scheduling approach is typically used in a repetitive manufacturing environment?
- Job-order scheduling with unique routings
- Rate-based scheduling tied to daily/weekly production rates (Correct answer)
- Project scheduling with Gantt charts
- Backward scheduling from delivery date only
Correct answer: Rate-based scheduling tied to daily/weekly production rates
Repetitive manufacturing uses rate-based scheduling, where production is scheduled as a rate per period (e.g., 200 units/day) rather than as discrete work orders.
Question 5: A machine center has a load of 500 hours scheduled in a 400-hour capacity week. What is the best short-term corrective action?
- Reduce the safety stock level
- Authorize overtime or use an alternate work center (Correct answer)
- Cancel some work orders permanently
- Increase the reorder point
Correct answer: Authorize overtime or use an alternate work center
When short-term overloads occur, the typical corrective actions are authorizing overtime, adding shifts, or routing work to an alternate capable work center.
Question 6: What does 'schedule adherence' measure in a manufacturing plant?
- The percentage of customer orders shipped on time
- The percentage of work orders completed as scheduled in the detailed plan (Correct answer)
- The accuracy of the sales forecast
- The efficiency of the purchasing department
Correct answer: The percentage of work orders completed as scheduled in the detailed plan
Schedule adherence measures how well the shop floor executes the detailed schedule by tracking what percentage of work orders are completed on time as planned.
Question 7: Which scheduling rule tends to minimize the average number of jobs in the system (WIP)?
- Earliest Due Date (EDD)
- First Come First Served (FCFS)
- Shortest Processing Time (SPT) (Correct answer)
- Longest Processing Time (LPT)
Correct answer: Shortest Processing Time (SPT)
SPT minimizes average flow time and average WIP by completing short jobs quickly and clearing queue, proven mathematically optimal for minimizing average job completion time.
CPIM Detailed Scheduling 4
What is 'Operation Splitting' and why is it used in detailed scheduling?