CPT Manufacturing Processes & Production 3 — Questions and Answers
Question 1: What is the primary purpose of a 'poka-yoke' device in manufacturing?
- To reduce machine cycle time
- To prevent or detect errors before they become defects (Correct answer)
- To track work-in-process inventory
- To schedule preventive maintenance
Correct answer: To prevent or detect errors before they become defects
Poka-yoke (mistake-proofing) devices are designed to prevent operator errors or immediately detect defects, eliminating the possibility of defects reaching downstream processes.
Question 2: In sheet metal fabrication, what process uses a punch and die to cut a blank shape from flat sheet stock?
- Forming
- Blanking (Correct answer)
- Bending
- Drawing
Correct answer: Blanking
Blanking uses a punch and die to shear a flat piece (blank) from sheet metal stock, which then becomes the workpiece for further operations.
Question 3: Which production scheduling method produces only what is needed, when it is needed, in the quantity needed?
- Push scheduling
- MRP (Material Requirements Planning)
- Just-In-Time (JIT) (Correct answer)
- Batch production
Correct answer: Just-In-Time (JIT)
Just-In-Time (JIT) production aligns output precisely with demand, minimizing inventory and waste by producing only what is needed at exactly the right time.
Question 4: What is the function of a 'relief angle' on a cutting tool?
- To direct chip flow away from the cut
- To prevent the tool flank from rubbing against the workpiece (Correct answer)
- To increase the tool's cutting edge hardness
- To control the depth of cut
Correct answer: To prevent the tool flank from rubbing against the workpiece
The relief angle (clearance angle) on a cutting tool prevents the tool's flank face from rubbing against the freshly machined workpiece surface, reducing friction and heat.
Question 5: In extrusion manufacturing, what distinguishes 'direct extrusion' from 'indirect extrusion'?
- Direct uses heat; indirect is cold
- In direct extrusion, the ram and material move in the same direction; in indirect, the die moves toward the billet (Correct answer)
- Direct produces hollow profiles; indirect produces solid profiles
- Direct is continuous; indirect is batch-only
Correct answer: In direct extrusion, the ram and material move in the same direction; in indirect, the die moves toward the billet
In direct (forward) extrusion, the ram pushes the billet through a stationary die; in indirect (backward) extrusion, the die moves into the stationary billet, reducing friction.
Question 6: A machine produces parts with a process capability index (Cpk) of 0.85. What does this indicate?
- The process is highly capable and centered
- The process does not fully meet specification limits and may produce defects (Correct answer)
- The process is capable only at lower volumes
- The process has excessive variation but is centered
Correct answer: The process does not fully meet specification limits and may produce defects
A Cpk below 1.0 indicates the process is not fully capable — it extends beyond at least one specification limit, resulting in some nonconforming parts.
Question 7: Which casting process forces molten metal into a permanent steel mold under high pressure, producing high-volume, dimensionally accurate parts?
- Sand casting
- Investment casting
- Die casting (Correct answer)
- Centrifugal casting
Correct answer: Die casting
Die casting injects molten metal into hardened steel molds under high pressure, enabling high production rates with excellent dimensional accuracy and smooth surface finishes.
CPT Manufacturing Processes & Production 3
What is the primary purpose of a 'poka-yoke' device in manufacturing?