NIMS CNC Milling Level II Certification Exam
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. What is the primary purpose of cutter radius compensation
(G41/G42) in CNC milling?
A. Adjust spindle speed automatically
B. Compensate for tool length error
C. Allow the programmer to adjust part size without changing
the program path
D. Control feed rate during contouring
It allows dimensional adjustments by shifting the tool path based
on cutter radius.
2. When using climb milling, the cutter rotation direction causes the
chip thickness to be:
A. Thin at entry and thick at exit
B. Constant throughout the cut
C. Thick at entry and thin at exit
D. Random depending on material
Climb milling starts with maximum chip thickness, reducing tool
wear and improving finish.
3. Which G-code is used to cancel cutter radius compensation?
A. G40
B. G40
C. G41
, D. G42
G40 cancels cutter radius compensation mode.
4. A helical interpolation is most commonly used to:
A. Face mill large surfaces
B. Profile external contours
C. Mill circular pockets or holes
D. Cut keyways
Helical interpolation combines circular motion with linear Z
movement for hole milling.
5. What is the main function of a ball end mill?
A. Drilling holes
B. Face milling
C. Contouring 3D surfaces
D. Slotting only
Ball end mills are ideal for complex 3D contours and surfaces.
6. Which tool is best suited for finishing a flat surface?
A. Roughing end mill
B. Ball end mill
C. Face mill
D. Slitting saw
Face mills provide smooth finishes on flat surfaces.
7. In CNC milling, backlash compensation is primarily related to:
A. Tool wear
B. Spindle speed variation
C. Lead screw and axis reversal error
D. Coolant flow rate
, Backlash occurs when reversing axis direction due to mechanical
play.
8. Which workholding method provides the highest rigidity for
precision milling?
A. Strap clamps
B. Vacuum table
C. Precision vise with parallels
D. Magnetic chuck
A precision vise ensures repeatable and rigid clamping.
9. What does G43 indicate in a CNC milling program?
A. Cancel tool length offset
B. Activate cutter comp right
C. Apply tool length compensation positive
D. Rapid positioning
G43 applies the tool length offset stored in the controller.
10. Which factor most affects surface finish during milling?
A. Tool holder type
B. Coolant color
C. Feed rate and tool condition
D. Machine paint color
Feed rate and sharp tools are critical for surface quality.
11. What is the main purpose of a roughing end mill?
A. High-precision finishing
B. Rapid material removal
C. Drilling holes
D. Chamfering edges
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of cutter radius compensation
(G41/G42) in CNC milling?
A. Adjust spindle speed automatically
B. Compensate for tool length error
C. Allow the programmer to adjust part size without changing
the program path
D. Control feed rate during contouring
It allows dimensional adjustments by shifting the tool path based
on cutter radius.
2. When using climb milling, the cutter rotation direction causes the
chip thickness to be:
A. Thin at entry and thick at exit
B. Constant throughout the cut
C. Thick at entry and thin at exit
D. Random depending on material
Climb milling starts with maximum chip thickness, reducing tool
wear and improving finish.
3. Which G-code is used to cancel cutter radius compensation?
A. G40
B. G40
C. G41
, D. G42
G40 cancels cutter radius compensation mode.
4. A helical interpolation is most commonly used to:
A. Face mill large surfaces
B. Profile external contours
C. Mill circular pockets or holes
D. Cut keyways
Helical interpolation combines circular motion with linear Z
movement for hole milling.
5. What is the main function of a ball end mill?
A. Drilling holes
B. Face milling
C. Contouring 3D surfaces
D. Slotting only
Ball end mills are ideal for complex 3D contours and surfaces.
6. Which tool is best suited for finishing a flat surface?
A. Roughing end mill
B. Ball end mill
C. Face mill
D. Slitting saw
Face mills provide smooth finishes on flat surfaces.
7. In CNC milling, backlash compensation is primarily related to:
A. Tool wear
B. Spindle speed variation
C. Lead screw and axis reversal error
D. Coolant flow rate
, Backlash occurs when reversing axis direction due to mechanical
play.
8. Which workholding method provides the highest rigidity for
precision milling?
A. Strap clamps
B. Vacuum table
C. Precision vise with parallels
D. Magnetic chuck
A precision vise ensures repeatable and rigid clamping.
9. What does G43 indicate in a CNC milling program?
A. Cancel tool length offset
B. Activate cutter comp right
C. Apply tool length compensation positive
D. Rapid positioning
G43 applies the tool length offset stored in the controller.
10. Which factor most affects surface finish during milling?
A. Tool holder type
B. Coolant color
C. Feed rate and tool condition
D. Machine paint color
Feed rate and sharp tools are critical for surface quality.
11. What is the main purpose of a roughing end mill?
A. High-precision finishing
B. Rapid material removal
C. Drilling holes
D. Chamfering edges
