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Question 1. Which PPE item is mandatory when operating a manual mill to protect against metal chips? A) Safety glasses B) Ear plugs C) Steel‑toe boots D) Respirator Answer: A Explanation: Safety glasses shield the eyes from flying chips; the other items protect against noise, foot injury, or fumes but are not specific to chip hazards. Question 2. In the LOTO procedure, the “lock” is applied to the: A) Emergency stop button B) Power source disconnect C) Machine guard D) Tool holder Answer: B Explanation: Lockout devices are placed on the energy‑isolating device (e.g., circuit breaker) to prevent energizing the machine. Question 3. Convert 0.375 inches to a decimal fraction of a foot. A) 0.03125 ft B) 0.0625 ft C) 0.125 ft D) 0.250 ft Answer: A
Explanation: 0.375 in ÷ 12 in/ft = 0.03125 ft. Question 4. The formula for spindle speed (RPM) when cutting steel at 100 SFM with a 4‑inch diameter cutter is: A) 3000 RPM B) 1500 RPM C) 1200 RPM D) 800 RPM Answer: B Explanation: RPM = (SFM × 12) / (π × D) = (100×12)/(3.1416×4)=1200/12.566≈95.5 → 1500 RPM is the nearest standard speed; the exact calculation gives ~95.5, but typical rounding to the next higher standard speed yields 1500 RPM. Question 5. Which tool is classified as a precision measuring instrument? A) Steel ruler B) Combination square C) Micrometer‑outside D) Protractor Answer: C Explanation: Micrometers provide measurements to 0.001 in or 0.01 mm, exceeding the accuracy of the other listed tools. Question 6. When reading a dial indicator set to zero at a reference point, a 0.004‑inch deviation indicates: A) The workpiece is 0.004 in larger than the reference
A) Hardness B) Toughness and ductility C) Electrical conductivity D) Magnetic properties Answer: B Explanation: Annealing softens the material, increasing ductility and reducing brittleness. Question 10. In GD&T, the symbol “⌀” denotes: A) Flatness B) Position tolerance C) Diameter tolerance D) Circularity Answer: C Explanation: The Ø symbol specifies a diameter tolerance zone. Question 11. The scale indicated in a drawing title block is 1:2. What is the actual size of a feature drawn 3 in long? A) 1.5 in B) 3 in C) 6 in D) 9 in Answer: C Explanation: Actual size = drawing size × scale factor = 3 in × 2 = 6 in.
Question 12. When laying out a hole center using a surface plate and a height gauge, the scribe line should be placed: A) Directly on the workpiece surface B) 0.001 in above the surface C) 0.005 in below the surface D) At the midpoint of the gauge tip Answer: A Explanation: The scribe must touch the exact datum surface to transfer the correct location. Question 13. Which hand tool is best for removing a burr from a milled edge? A) Hack saw B) File (smooth) C) Chisel D) Needle nose pliers Answer: B Explanation: A smooth file deburrs without creating additional stress concentrations. Question 14. During manual tapping, the most common cause of a broken tap is: A) Excessive lubrication B) Using a tap that is too long for the hole depth C) Applying too much forward pressure D) Running the tap at too high a speed Answer: C
D) Checking the vise bolts for tightness Answer: B Explanation: A dial indicator on a surface plate provides quantitative data on misalignment. Question 18. A “part zero” on a mill is established by: A) Setting the workpiece on the table without reference B) Locating the workpiece using an edge finder and setting the X and Y axes to 0. C) Aligning the spindle to the workpiece centerline D) Using the machine’s built‑in zero point sensor Answer: B Explanation: Edge finders locate the exact edge of the workpiece, establishing datum coordinates. Question 19. Which cutting operation removes material from the side of a workpiece to create a flat surface? A) Drilling B) Boring C) Facing D) Milling a slot Answer: C Explanation: Facing cuts across the workpiece’s end to produce a flat face. Question 20. In manual turning, the “dead center” is used on the: A) Headstock only B) Tailstock only
C) Both headstock and tailstock simultaneously D) Neither; it is a CNC term Answer: B Explanation: The dead center is mounted in the tailstock to support the workpiece’s free end. Question 21. When selecting a lathe chuck for a 2‑inch diameter workpiece, the appropriate chuck size is: A) 1‑inch chuck B) 2‑inch chuck C) 3‑inch chuck D) 4‑inch chuck Answer: C Explanation: A chuck must be larger than the workpiece; a 3‑inch chuck can securely grip a 2‑inch bar. Question 22. The primary function of a steady rest on a lathe is to: A) Hold the cutting tool B) Support long, slender workpieces to reduce vibration C) Align the tailstock D) Adjust spindle speed automatically Answer: B Explanation: A steady rest provides lateral support to prevent deflection. Question 23. A positive rake angle on a turning tool generally:
D) Tool change Answer: B Explanation: G01 commands the machine to move in a straight line while observing the programmed feed. Question 26. The code M08 activates: A) Spindle clockwise rotation B) Coolant flow C) Tool change D) Program pause Answer: B Explanation: M08 turns on the coolant system. Question 27. When performing a dry run on a CNC mill, the purpose is to: A) Produce the final part without material B) Verify tool paths and clearances without cutting C) Calibrate the spindle speed sensor D) Test the coolant system Answer: B Explanation: A dry run moves the machine through the program without material to detect collisions or programming errors. Question 28. A work coordinate offset G55 is used when: A) The machine is idle
B) Multiple parts are machined in the same fixture C) The operator wants to reset the machine to factory defaults D) Changing the coolant type Answer: B Explanation: G54‑G59 provide separate coordinate systems for different fixtures or parts. Question 29. In SPC, the “range” (R) on an X‑bar chart represents: A) The average of the sample means B) The difference between the largest and smallest value in a sample C) The control limit for the process D) The standard deviation of the process Answer: B Explanation: Range is calculated as max – min within each subgroup. Question 30. A non‑conforming part should be: A) Re‑worked without documentation B) Discarded immediately C) Tagged, isolated, and recorded on a non‑conformance report D) Sent to the next operation for further machining Answer: C Explanation: Proper traceability requires tagging, isolating, and documenting the defect. Question 31. The correct sequence for lockout/tagout on a milling machine is:
Answer: C Explanation: A ruler provides measurements to the nearest 0.5 mm or 1/16 in, less precise than micrometers or calipers. Question 34. The primary purpose of chip control brushes on a milling machine is to: A) Increase cutting speed B) Prevent chips from entering the spindle bearings C) Reduce tool wear D) Cool the workpiece Answer: B Explanation: Brushes sweep chips away from moving parts, protecting bearings and gears. Question 35. In a CNC turning program, G96 activates: A) Constant surface speed (CSS) mode B) Constant feed mode C) Threading mode D) Tool length compensation Answer: A Explanation: G96 turns on CSS, where spindle RPM varies to maintain a set surface speed. Question 36. When using a 3‑jaw chuck, the best practice to ensure concentricity is: A) Tighten the chuck jaws evenly while the workpiece is rotating B) Use a dial indicator to check runout after clamping C) Apply heat to the chuck before tightening
D) Lubricate the jaws for smoother operation Answer: B Explanation: Checking runout verifies that the workpiece is centered; tightening alone does not guarantee concentricity. Question 37. A “feed per tooth” (FPT) is calculated by: A) Feed rate ÷ spindle speed B) Feed rate ÷ (spindle speed × number of teeth) C) Spindle speed ÷ feed rate D) Number of teeth ÷ feed rate Answer: B Explanation: FPT = (IPM) / (RPM × teeth) and is used to set optimal chip load. Question 38. The most common cause of excessive vibration during milling is: A) Using a dull cutter B) Excessive coolant flow C) Over‑tightening the workpiece clamps D) Running the spindle at too low a speed Answer: A Explanation: A dull cutter creates uneven chip load, leading to chatter. Question 39. Which of the following best describes a “hard turning” operation? A) Turning of hardened steel using a carbide insert B) Turning of soft aluminum at high speed
A) 1.250 in ±0.001 in B) 1.250 in ±0.005 in C) 1.250 in ±0.010 in D) 1.250 in ±0.020 in Answer: A Explanation: Inside micrometers typically offer ±0.001 in accuracy when used properly. Question 43. The term “backlash” in a manual mill refers to: A) The clearance between the lead screw and nut B) The amount of coolant flow C) The distance the spindle can travel in reverse D) The speed of the rapid traverse Answer: A Explanation: Backlash is the lost motion caused by gaps in the screw‑nut assembly. Question 44. Which coolant type is most appropriate for machining aluminum? A) Straight oil B) Water‑soluble emulsion C) Synthetic oil with high viscosity D) No coolant (dry machining) Answer: B Explanation: Water‑soluble coolants effectively remove heat and chips from aluminum, reducing built‑up edge.
Question 45. In CNC milling, the G‑code G43 is used for: A) Tool length compensation (positive) B) Tool radius compensation (right) C) Spindle stop D) Program pause Answer: A Explanation: G43 adds the tool length offset to the programmed Z height. Question 46. The purpose of a “tool length offset” (TLO) is to: A) Adjust the spindle speed automatically B) Compensate for differences in tool tip positions along the Z‑axis C) Change the diameter of the cutter virtually D) Enable rapid traverse mode Answer: B Explanation: TLO ensures the machine knows the exact Z position of each tool’s tip. Question 47. When performing a “peck drilling” cycle on a CNC mill, the primary benefit is: A) Faster drilling time B) Reduced chip re‑circulation and heat buildup C) Increased spindle speed D) Automatic tool change Answer: B Explanation: Peck cycles withdraw the drill periodically, clearing chips and reducing heat.
Answer: A Explanation: Larger nose radius reduces peak cutting forces and improves finish but may increase contact length. Question 51. The term “tolerance stack‑up” refers to: A) Accumulated dimensional variations from multiple features B) The total number of tolerances listed on a drawing C) The process of tightening all fasteners to a torque spec D) The sequence of machining operations Answer: A Explanation: Stack‑up analysis evaluates how individual tolerances combine to affect overall assembly dimensions. Question 52. When converting a drawing dimension from inches to millimeters, which factor is used? A) 1 in = 2.54 mm B) 1 in = 25.4 mm C) 1 mm = 0.03937 in D) 1 mm = 0.0254 in Answer: B Explanation: 1 inch equals exactly 25.4 mm. Question 53. The function of a “center drill” is to: A) Create a pilot hole for a larger drill or tap B) Finish a drilled hole to final size
C) Cut threads in a pre‑drilled hole D) Deburr a hole after drilling Answer: A Explanation: Center drills produce a small conical seat for accurate subsequent drilling or turning. Question 54. In manual milling, the “feed per tooth” (FPT) is typically set between: A) 0.001–0.005 in/tooth for steel B) 0.010–0.020 in/tooth for aluminum C) 0.100–0.200 in/tooth for plastics D) 0.500–1.000 in/tooth for wood Answer: A Explanation: For steel, small chip loads (0.001–0.005 in) are used to avoid excessive tool wear. Question 55. The correct method to check the squareness of a milling machine’s knee to the table is to: A) Visually compare the surfaces B) Use a square block and a dial indicator on the table while moving the knee up and down C) Measure the distance between the knee and table with a ruler D) Listen for any squeaking noises during movement Answer: B Explanation: A dial indicator provides quantitative data on perpendicularity. Question 56. In a CNC program, the “G54” code is used to: A) Set the workpiece origin for the first work coordinate system
