BME Advanced Manufacturing 5 — Questions and Answers
Question 1: In computer-aided process planning (CAPP), the variant approach works by:
- Generating a new process plan from scratch using AI for each new part
- Retrieving and modifying an existing plan for a similar part using group technology (Correct answer)
- Simulating machining operations in a virtual environment before cutting
- Automatically programming CNC machines from CAD files
Correct answer: Retrieving and modifying an existing plan for a similar part using group technology
The variant CAPP approach classifies the new part into a family, retrieves the standard plan for that family, then modifies it to suit the specific part's requirements.
Question 2: During deep drawing of sheet metal, wrinkling of the flange is typically prevented by:
- Increasing punch speed
- Applying a blank holder force to keep the flange flat (Correct answer)
- Reducing the die clearance below material thickness
- Heating the blank above recrystallization temperature
Correct answer: Applying a blank holder force to keep the flange flat
A blank holder applies a controlled force to the sheet flange, suppressing compressive instability that would otherwise cause wrinkling as the material flows inward.
Question 3: Which machining process is best suited for producing highly accurate flat reference surfaces on cast iron machine tool bases?
- Peripheral end milling
- Surface grinding (Correct answer)
- Broaching
- Plunge EDM
Correct answer: Surface grinding
Surface grinding uses a rotating abrasive wheel traversing the workpiece, achieving flatness tolerances and surface finishes unattainable by milling on hardened machine tool components.
Question 4: What does a high process capability index (Cpk > 1.67) indicate about a manufacturing process?
- The process frequently produces defects outside specification
- The process mean is well-centered and variation is well within specification limits (Correct answer)
- The sample size used for measurement is too large
- The control limits need to be widened
Correct answer: The process mean is well-centered and variation is well within specification limits
A Cpk above 1.67 means the process distribution fits comfortably within specification limits with ample margin, corresponding to fewer than 0.6 defects per million opportunities.
Question 5: In laser beam machining (LBM), the parameter most directly controlling the depth of material removed per pulse is:
- Beam diameter at the lens
- Peak power density (irradiance) at the workpiece surface (Correct answer)
- Wavelength of the laser source
- Assist gas pressure
Correct answer: Peak power density (irradiance) at the workpiece surface
Peak power density (W/cm²) determines whether the threshold for ablation, melting, or vaporization is exceeded and how deeply each pulse penetrates the material.
Question 6: Which of the following is the correct sequence of operations in investment casting?
- Pour metal → create wax pattern → build ceramic shell → dewax
- Create wax pattern → build ceramic shell → dewax → pour metal (Correct answer)
- Build ceramic shell → create wax pattern → pour metal → dewax
- Dewax → create wax pattern → pour metal → build ceramic shell
Correct answer: Create wax pattern → build ceramic shell → dewax → pour metal
Investment casting begins with a wax pattern, which is coated in ceramic slurry to build the shell, then the wax is melted out (lost-wax), and finally molten metal is poured.
Question 7: What is the primary purpose of applying a TiN (titanium nitride) coating to a high-speed steel cutting tool?
- Increasing the tool's magnetic permeability
- Improving hardness, wear resistance, and reducing friction at the cutting edge (Correct answer)
- Making the tool detectable by metal sensors on the shop floor
- Increasing thermal conductivity to draw heat away from the edge
Correct answer: Improving hardness, wear resistance, and reducing friction at the cutting edge
TiN coatings provide a hard, low-friction surface on the tool, reducing flank wear and built-up edge formation, significantly extending tool life.
BME Advanced Manufacturing 5
In computer-aided process planning (CAPP), the variant approach works by: