CNC MACHINE MAINTENANCE TECHNICIAN
CERTIFICATION EXAM QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
1. Which type of lubricant is most commonly used for CNC machine
ways?
a) Hydraulic oil
b) Way oil
c) Cutting fluid
d) Gear oil
Way oil is specifically designed to adhere to machine ways, providing
proper lubrication and minimizing wear.
2. What is the main purpose of a spindle in a CNC machine?
a) Move the table
b) Hold and rotate the cutting tool
c) Control coolant flow
d) Support the workpiece
The spindle is responsible for rotating the cutting tool at controlled
speeds and feeds, enabling material removal.
3. How often should CNC machine linear guides be inspected for
wear?
a) Every 12 months
b) Before each major production run or monthly
c) Only when unusual noise occurs
d) Once every 5 years
,Regular inspection prevents unexpected downtime and maintains
machining accuracy.
4. Which component converts electrical signals into precise
mechanical movement in a CNC machine?
a) Spindle
b) Servo motor
c) Stepper motor or servo motor
d) Ball screw
Stepper and servo motors respond to electrical pulses, moving axes with
high precision.
5. What is backlash in CNC machines?
a) Excessive vibration of the spindle
b) Lost motion between mechanical components
c) Overheating of the motor
d) Improper tool alignment
Backlash occurs due to clearance between components, leading to
positional errors.
6. What is the primary function of a ball screw in CNC machinery?
a) Cool the spindle
b) Convert rotary motion to linear motion with minimal backlash
c) Rotate the cutting tool
d) Support the workpiece
Ball screws provide precise linear motion while reducing friction and
wear.
7. Which device measures the exact position of a CNC axis?
a) Thermocouple
b) Resolver
, c) Linear encoder
d) Hydraulic sensor
Linear encoders detect axis position directly and provide feedback to the
control system.
8. What is the recommended procedure if a CNC machine axis is
moving unevenly?
a) Replace the spindle
b) Check lubrication, ball screws, and guideways for wear or
debris
c) Reinstall the software
d) Adjust cutting speeds
Uneven movement often results from mechanical issues such as debris
or wear, not software errors.
9. Which type of coolant is preferred for general metal cutting in
CNC machining?
a) Air
b) Water-soluble cutting fluid
c) Hydraulic oil
d) Pure oil
Water-soluble cutting fluids offer effective cooling and moderate
lubrication for a wide range of metals.
10. How often should spindle bearings be lubricated in high-
usage CNC machines?
a) Every 6 months
b) According to manufacturer recommendations, often monthly
or weekly
c) Only when noise develops
d) Every 5 years
CERTIFICATION EXAM QUESTIONS AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS RATIONALES
2026 Q&A | INSTANT DOWNLOAD PDF
1. Which type of lubricant is most commonly used for CNC machine
ways?
a) Hydraulic oil
b) Way oil
c) Cutting fluid
d) Gear oil
Way oil is specifically designed to adhere to machine ways, providing
proper lubrication and minimizing wear.
2. What is the main purpose of a spindle in a CNC machine?
a) Move the table
b) Hold and rotate the cutting tool
c) Control coolant flow
d) Support the workpiece
The spindle is responsible for rotating the cutting tool at controlled
speeds and feeds, enabling material removal.
3. How often should CNC machine linear guides be inspected for
wear?
a) Every 12 months
b) Before each major production run or monthly
c) Only when unusual noise occurs
d) Once every 5 years
,Regular inspection prevents unexpected downtime and maintains
machining accuracy.
4. Which component converts electrical signals into precise
mechanical movement in a CNC machine?
a) Spindle
b) Servo motor
c) Stepper motor or servo motor
d) Ball screw
Stepper and servo motors respond to electrical pulses, moving axes with
high precision.
5. What is backlash in CNC machines?
a) Excessive vibration of the spindle
b) Lost motion between mechanical components
c) Overheating of the motor
d) Improper tool alignment
Backlash occurs due to clearance between components, leading to
positional errors.
6. What is the primary function of a ball screw in CNC machinery?
a) Cool the spindle
b) Convert rotary motion to linear motion with minimal backlash
c) Rotate the cutting tool
d) Support the workpiece
Ball screws provide precise linear motion while reducing friction and
wear.
7. Which device measures the exact position of a CNC axis?
a) Thermocouple
b) Resolver
, c) Linear encoder
d) Hydraulic sensor
Linear encoders detect axis position directly and provide feedback to the
control system.
8. What is the recommended procedure if a CNC machine axis is
moving unevenly?
a) Replace the spindle
b) Check lubrication, ball screws, and guideways for wear or
debris
c) Reinstall the software
d) Adjust cutting speeds
Uneven movement often results from mechanical issues such as debris
or wear, not software errors.
9. Which type of coolant is preferred for general metal cutting in
CNC machining?
a) Air
b) Water-soluble cutting fluid
c) Hydraulic oil
d) Pure oil
Water-soluble cutting fluids offer effective cooling and moderate
lubrication for a wide range of metals.
10. How often should spindle bearings be lubricated in high-
usage CNC machines?
a) Every 6 months
b) According to manufacturer recommendations, often monthly
or weekly
c) Only when noise develops
d) Every 5 years
