CMS Manufacturing Processes & Techniques 2 — Questions and Answers
Question 1: In electrical discharge machining (EDM), material removal occurs through which mechanism?
- Mechanical abrasion between tool and workpiece
- Controlled electrical sparks that erode the workpiece (Correct answer)
- Chemical dissolution of the workpiece surface
- High-pressure fluid jet cutting
Correct answer: Controlled electrical sparks that erode the workpiece
EDM removes material through precisely controlled electrical sparks (discharges) that vaporize and erode the workpiece without direct contact.
Question 2: Which forming process uses a rotating mandrel and a roller tool to shape sheet metal into axisymmetric parts?
- Deep drawing
- Spin forming (metal spinning) (Correct answer)
- Roll forming
- Hydroforming
Correct answer: Spin forming (metal spinning)
Metal spinning (spin forming) rotates a metal blank against a mandrel while a roller tool progressively shapes it into a hollow, axisymmetric component.
Question 3: What is the primary purpose of a riser in a sand casting mold?
- To vent gases from the mold cavity
- To feed molten metal and compensate for shrinkage during solidification (Correct answer)
- To support the mold cope during pouring
- To create internal passages in the casting
Correct answer: To feed molten metal and compensate for shrinkage during solidification
Risers are reservoirs of molten metal that feed the casting as it solidifies and shrinks, preventing shrinkage voids in the finished part.
Question 4: During a turning operation, increasing the depth of cut while keeping feed rate and cutting speed constant will primarily:
- Decrease cutting forces and tool wear
- Increase material removal rate and cutting forces (Correct answer)
- Improve surface finish and dimensional accuracy
- Reduce built-up edge formation on the tool
Correct answer: Increase material removal rate and cutting forces
Increasing depth of cut raises the volume of material removed per pass, which simultaneously increases cutting forces and tool loading.
Question 5: Which welding defect is characterized by a groove melted into the base metal along the weld toe that is not filled by weld metal?
- Porosity
- Incomplete fusion
- Undercut (Correct answer)
- Overlap
Correct answer: Undercut
Undercut is a groove or channel burned into the base metal adjacent to the weld toe, reducing the effective cross-section and creating a stress concentration.
Question 6: In powder metallurgy, the step that converts a green compact into a strong part by heating below the melting point is called:
- Annealing
- Sintering (Correct answer)
- Quenching
- Tempering
Correct answer: Sintering
Sintering heats the green compact to a temperature below its melting point, causing particle bonding through diffusion and densification without full melting.
Question 7: What advantage does friction stir welding (FSW) have over conventional fusion welding for aluminum alloys?
- It produces higher heat input, improving penetration
- It requires no shielding gas and operates below the melting point, reducing distortion (Correct answer)
- It is faster and requires more complex equipment
- It creates deeper weld penetration due to arc pressure
Correct answer: It requires no shielding gas and operates below the melting point, reducing distortion
FSW is a solid-state process that operates below the melting point, resulting in lower distortion, finer microstructure, and no need for shielding gas or filler metal.
CMS Manufacturing Processes & Techniques 2
In electrical discharge machining (EDM), material removal occurs through which mechanism?