NIMS CNC Operator Certification Exam

National Institute for Metalworking Skills (NIMS) CNC Operator Certification Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary function of a CNC machine?

a) To manually control machine tools

b) To automatically control machining operations using programmed

instructions

c) To automatically control machining operations using programmed

instructions

d) To measure finished parts

Rationale: CNC (Computer Numerical Control) machines use computer

programs to automate and control machining processes, increasing accuracy and productivity.

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• What does G00 represent in CNC programming?

a) Linear interpolation

b) Rapid positioning

c) Circular interpolation

d) Feed hold

Rationale: G00 is used for rapid positioning moves without cutting, moving

the tool quickly to a specified coordinate.

• Which coordinate system is most commonly used in CNC machining?

a) Polar

b) Cartesian

c) Cylindrical

d) Relative

Rationale: CNC machines typically use the Cartesian coordinate system (X,

Y, Z axes) to define tool movements.

• What does M03 command do in a CNC program?

a) Spindle stop

b) Spindle on clockwise

c) Spindle on counterclockwise

d) Coolant on

Rationale: M03 turns the spindle on in the clockwise direction, typically

used for most machining operations. 2 / 4

• Which tool would be used to check the diameter of a small hole

accurately?

a) Vernier caliper

b) Steel rule

c) Telescoping gauge with micrometer

d) Depth micrometer

Rationale: A telescoping gauge transfers the hole size, and a micrometer

measures it accurately.

6. The "feed rate" in CNC machining refers to:

a) The speed of spindle rotation

b) The speed at which the cutting tool advances into the material

c) The rate of coolant flow

d) The rate of chip removal

Rationale: Feed rate is the linear distance the tool travels per minute or per

revolution during cutting.

• What unit is spindle speed typically measured in?

a) Inches per minute

b) Revolutions per minute (RPM)

c) Feet per second 3 / 4

d) Degrees per second

Rationale: Spindle speed is measured in revolutions per minute, indicating

how fast the spindle rotates.

8. G01 command in CNC programming indicates:

a) Rapid move

b) Linear interpolation at feed rate

c) Tool change

d) Stop program

Rationale: G01 performs a controlled linear cutting move at the specified

feed rate.

• What is the purpose of tool offsets in CNC machines?

a) To calibrate spindle rotation

b) To compensate for tool length and diameter differences

c) To measure part dimensions

d) To stop the machine in an emergency

Rationale: Tool offsets adjust the tool’s position for its actual dimensions,

ensuring accurate machining.

• What does M06 represent in a CNC program?

a) End of program

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