Production planning & control (PPC): job-order vs mass production Evaluate the statement: “The planning and scheduling of job-order (job shop) manufacturing differ significantly from planning and scheduling of mass production.”
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ACorrect
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BIncorrect
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CCorrect only when product variety is zero
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DIncorrect unless automation is present
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ECorrect only for service industries
Answer
Correct Answer: Correct
Explanation
Introduction / Context:Production Planning and Control (PPC) adapts to the manufacturing environment. Job-order (job shop) manufacturing handles high variety and low volume, while mass production focuses on standardized products and high volumes. Their planning and scheduling philosophies therefore diverge.
Given Data / Assumptions:
- Job shop: functional layout, variable routing, frequent changeovers.
- Mass production: product or cellular layout, stable routing, repeatability.
- Objective: compare planning and scheduling approaches.
Concept / Approach:Job shops require detailed routing, order-specific lead-time estimation, finite-capacity scheduling, and dispatching rules (e.g., shortest processing time). Mass production relies on line balancing, takt time, material requirements planning (MRP), and repetitive scheduling with minimal variability.
Step-by-Step Solution:Identify variability: job shops face frequent mix and sequence changes → complex, dynamic schedules.Relate tools: Gantt charts, priority dispatching, and capacity-constrained routing dominate job shops.For mass production, determine takt and balance stations to meet demand; schedules repeat cyclically.Thus, planning and scheduling indeed differ markedly.
Verification / Alternative check:Industry practice shows ERP/MRP-II with repetitive manufacturing modules for mass production, vs advanced planning and scheduling (APS) or shop-floor dispatching for job shops.
Why Other Options Are Wrong:(B) ignores fundamental environment differences; (C) and (E) add irrelevant constraints; (D) misstates the role of automation, which is not the primary determinant.
Common Pitfalls:Applying line-balancing concepts to job shops; underestimating setup times and routing complexity; assuming one PPC method fits all.
Final Answer:Correct