NIMS CNC Milling Level I Certification
Exam | Questions and Answers Plus
Rationales | Instant Download Pdf 2026
Update
1. What is the primary purpose of a work offset such as G54 in CNC milling?
a) To set the spindle speed
b) To define the zero point of the workpiece relative to the machine reference
c) To select the cutting tool
d) To control coolant flow
Answer: b
Rationale: G54 is a work coordinate system offset that tells the CNC machine where the
workpiece zero (part origin) is located relative to the machine home position, enabling
consistent machining.
2. Which G-code is used for linear interpolation at a specified feed rate?
a) G00
b) G01
c) G02
d) G03
Answer: b
Rationale: G01 commands linear interpolation (straight line movement) at a
programmed feed rate (F address). G00 is rapid positioning, G02 and G03 are circular
interpolation.
3. During a milling operation, what is the effect of increasing spindle speed while
keeping feed rate constant?
a) Chip load increases
, b) Chip load decreases
c) Surface finish worsens
d) Tool life always increases
Answer: b
Rationale: Chip load = feed rate / (spindle speed × number of flutes). Higher spindle
speed reduces chip thickness, which can improve surface finish but risk rubbing if too
low.
4. In a CNC mill, which component is responsible for precise positioning of the table
along the X-axis?
a) Spindle motor
b) Ball screw and servo motor
c) Turret
d) Coolant pump
Answer: b
Rationale: The ball screw converts rotary motion of the servo motor into linear motion,
providing precise and backlash-free positioning of the table.
5. What does the M03 M-code command do?
a) Stop the spindle
b) Start spindle clockwise rotation
c) Start spindle counterclockwise rotation
d) Turn on coolant
Answer: b
Rationale: M03 starts the spindle rotating clockwise (forward) at the programmed S-
code speed. M04 is counterclockwise, M05 stops.
6. The tool length offset is typically stored in which register?
a) H register (e.g., H01)
b) D register (e.g., D01)
, c) T register
d) G register
Answer: a
Rationale: H offsets store tool length compensation values. D registers store cutter
diameter/radius compensation.
7. When climb milling with a CNC mill, the chip thickness:
a) Starts at zero and increases
b) Starts maximum and decreases
c) Remains constant
d) Is irrelevant
Answer: a
Rationale: In climb milling (down milling), the cutter tooth engages at zero chip
thickness and exits at maximum, reducing work hardening and improving finish.
8. Which G-code cancels cutter radius compensation?
a) G40
b) G41
c) G42
d) G43
Answer: a
Rationale: G40 cancels both left (G41) and right (G42) cutter compensation. G43 is tool
length compensation positive.
9. What is the purpose of the coolant during milling of aluminum?
a) Only to clean chips
b) To lubricate and remove heat
c) To increase tool hardness
d) To change part dimensions
, Answer: b
Rationale: Coolant reduces friction, carries away heat, prevents built-up edge on cutting
tool, and flushes chips from the cutting zone.
10. Which type of tool holder provides the highest grip strength for high-speed
milling?
a) Set screw holder
b) Weldon shank holder
c) Hydraulic chuck
d) ER collet chuck
Answer: c
Rationale: Hydraulic chucks provide uniform clamping pressure, high grip torque,
excellent runout control, and vibration damping for high-speed operations.
11. The command G90 in a CNC program sets:
a) Incremental positioning
b) Absolute positioning
c) Metric units
d) Inch units
Answer: b
Rationale: G90 selects absolute coordinate mode where all coordinates are referenced
from the part zero (work offset). G91 is incremental.
12. What does the address "F" specify in a milling program?
a) Feed rate
b) Spindle speed
c) Tool number
d) Fixture offset
Exam | Questions and Answers Plus
Rationales | Instant Download Pdf 2026
Update
1. What is the primary purpose of a work offset such as G54 in CNC milling?
a) To set the spindle speed
b) To define the zero point of the workpiece relative to the machine reference
c) To select the cutting tool
d) To control coolant flow
Answer: b
Rationale: G54 is a work coordinate system offset that tells the CNC machine where the
workpiece zero (part origin) is located relative to the machine home position, enabling
consistent machining.
2. Which G-code is used for linear interpolation at a specified feed rate?
a) G00
b) G01
c) G02
d) G03
Answer: b
Rationale: G01 commands linear interpolation (straight line movement) at a
programmed feed rate (F address). G00 is rapid positioning, G02 and G03 are circular
interpolation.
3. During a milling operation, what is the effect of increasing spindle speed while
keeping feed rate constant?
a) Chip load increases
, b) Chip load decreases
c) Surface finish worsens
d) Tool life always increases
Answer: b
Rationale: Chip load = feed rate / (spindle speed × number of flutes). Higher spindle
speed reduces chip thickness, which can improve surface finish but risk rubbing if too
low.
4. In a CNC mill, which component is responsible for precise positioning of the table
along the X-axis?
a) Spindle motor
b) Ball screw and servo motor
c) Turret
d) Coolant pump
Answer: b
Rationale: The ball screw converts rotary motion of the servo motor into linear motion,
providing precise and backlash-free positioning of the table.
5. What does the M03 M-code command do?
a) Stop the spindle
b) Start spindle clockwise rotation
c) Start spindle counterclockwise rotation
d) Turn on coolant
Answer: b
Rationale: M03 starts the spindle rotating clockwise (forward) at the programmed S-
code speed. M04 is counterclockwise, M05 stops.
6. The tool length offset is typically stored in which register?
a) H register (e.g., H01)
b) D register (e.g., D01)
, c) T register
d) G register
Answer: a
Rationale: H offsets store tool length compensation values. D registers store cutter
diameter/radius compensation.
7. When climb milling with a CNC mill, the chip thickness:
a) Starts at zero and increases
b) Starts maximum and decreases
c) Remains constant
d) Is irrelevant
Answer: a
Rationale: In climb milling (down milling), the cutter tooth engages at zero chip
thickness and exits at maximum, reducing work hardening and improving finish.
8. Which G-code cancels cutter radius compensation?
a) G40
b) G41
c) G42
d) G43
Answer: a
Rationale: G40 cancels both left (G41) and right (G42) cutter compensation. G43 is tool
length compensation positive.
9. What is the purpose of the coolant during milling of aluminum?
a) Only to clean chips
b) To lubricate and remove heat
c) To increase tool hardness
d) To change part dimensions
, Answer: b
Rationale: Coolant reduces friction, carries away heat, prevents built-up edge on cutting
tool, and flushes chips from the cutting zone.
10. Which type of tool holder provides the highest grip strength for high-speed
milling?
a) Set screw holder
b) Weldon shank holder
c) Hydraulic chuck
d) ER collet chuck
Answer: c
Rationale: Hydraulic chucks provide uniform clamping pressure, high grip torque,
excellent runout control, and vibration damping for high-speed operations.
11. The command G90 in a CNC program sets:
a) Incremental positioning
b) Absolute positioning
c) Metric units
d) Inch units
Answer: b
Rationale: G90 selects absolute coordinate mode where all coordinates are referenced
from the part zero (work offset). G91 is incremental.
12. What does the address "F" specify in a milling program?
a) Feed rate
b) Spindle speed
c) Tool number
d) Fixture offset
