CNC Machinist Certification Practice Test

CNC Machinist Certification Practice Test

This test is designed to help you prepare for the actual certification exam by assessing your knowledge of CNC machining concepts, programming, operations, and safety practices.

The test consists of 50 multiple-choice questions covering a wide range of topics relevant to CNC machining.

Take your time, read each question carefully, and choose the best answer.

Good luck!

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CNC Machinist Certification Practice Test

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Your answers are highlighted below.
Question 1
What does CNC stand for?
A
Computer Numerical Control
B
Computer Network Control
C
Computerized Navigation Control
D
Centralized Numerical Control
Question 2
Which of the following is a primary function of a CNC machine?
A
Welding
B
Cutting and shaping materials
C
Painting
D
Assembling parts
Question 3
What type of coordinate system is used in CNC programming?
A
Polar
B
Cartesian
C
Cylindrical
D
Spherical
Question 4
Which axis is typically vertical in a CNC milling machine?
A
X-axis
B
Y-axis
C
Z-axis
D
A-axis
Question 5
What is the purpose of G-code in CNC programming?
A
To define tool paths and machine operations
B
To create 3D models
C
To measure tool wear
D
To calibrate the machine
Question 6
Which G-code command is used for a linear interpolation move?
A
G00
B
G01
C
G02
D
G03
Question 7
What does the M03 command do?
A
Starts the spindle rotation clockwise
B
Stops the spindle
C
Turns on coolant
D
Moves the tool to home position
Question 8
Which command is used to stop the program temporarily?
A
M00
B
M01
C
M02
D
M30
Question 9
What is the purpose of the G28 command?
A
Return to machine home position
B
Start a tool change
C
Move the tool in a circular path
D
Adjust feed rate
Question 10
Which code is used to define a tool offset?
A
G40
B
G41
C
G42
D
G43
Question 11
What is the primary purpose of a CNC lathe?
A
Drilling holes
B
Cutting external and internal threads
C
Milling flat surfaces
D
Engraving
Question 12
Which cutting tool is commonly used for milling operations?
A
Drill bit
B
End mill
C
Tap
D
Reamer
Question 13
What is the function of coolant in CNC machining?
A
To lubricate and cool the cutting tool
B
To clean the workpiece
C
To increase spindle speed
D
To measure tool wear
Question 14
What is the purpose of a workpiece zero point?
A
To define the origin for the CNC program
B
To calibrate the spindle
C
To measure tool length
D
To adjust feed rate
Question 15
Which of the following is a common CNC milling operation?
A
Turning
B
Facing
C
Boring
D
All of the above
Question 16
What is the first step before operating a CNC machine?
A
Load the program
B
Check the machine for any abnormalities
C
Start the spindle
D
Adjust the feed rate
Question 17
Which personal protective equipment (PPE) is essential when operating a CNC machine?
A
Safety glasses
B
Earplugs
C
Gloves
D
All of the above 
Question 18
What should you do if you notice unusual vibrations during machining?
A
Increase the feed rate
B
Stop the machine and inspect
C
Ignore it and continue
D
Adjust the coolant flow 
Question 19
Why is it important to secure the workpiece properly?
A
To prevent accidents and ensure accuracy
B
To increase spindle speed
C
To reduce tool wear
D
To improve surface finish
Question 20
What is the purpose of an emergency stop button?
A
To pause the program
B
To immediately halt all machine operations
C
To reset the machine
D
To change tools
Question 21
What is the primary purpose of regular machine maintenance?
A
To increase production speed
B
To ensure machine accuracy and longevity
C
To reduce coolant usage
D
To improve programming efficiency
Question 22
Which component should be checked for wear during maintenance?
A
Spindle
B
Cutting tools
C
Guideways
D
All of the above
Question 23
What is the recommended frequency for cleaning CNC machines?
A
Daily
B
Weekly
C
Monthly
D
Annually
Question 24
Which lubricant is commonly used for CNC machine guideways?
A
Water-based coolant
B
Grease
C
Oil
D
WD-40
Question 25
What should be done if a CNC machine produces inconsistent parts?
A
Increase feed rate
B
Check for worn tools or misalignment
C
Reduce spindle speed
D
Ignore the issue
Question 26
What is the purpose of a CNC probe?
A
To measure tool length
B
To inspect workpiece dimensions
C
To clean the machine
D
To adjust feed rate 
Question 27
Which software is commonly used for CNC programming?
A
AutoCAD
B
Mastercam
C
SolidWorks
D
All of the above
Question 28
What is the function of a post-processor in CNC programming?
A
To convert CAD models into G-code
B
To measure tool wear
C
To adjust spindle speed
D
To clean the machine
Question 29
What is the purpose of a tool turret in a CNC lathe?
A
To hold multiple tools for automatic changes
B
To measure workpiece dimensions
C
To adjust feed rate
D
To clean the machine
Question 30
What is the advantage of using high-speed machining?
A
Reduced cycle time
B
Improved surface finish
C
Extended tool life
D
All of the above
Question 31
What could cause a CNC machine to produce inaccurate parts?
A
Worn tools
B
Misaligned workpiece
C
Incorrect program
D
All of the above 
Question 32
What is the first step in troubleshooting a CNC machine?  
A
Check the program
B
Inspect the machine for abnormalities
C
Replace the cutting tool
D
Adjust the feed rate
Question 33
What could cause excessive tool wear?
A
High feed rate
B
Incorrect cutting speed
C
Lack of coolant
D
All of the above 
Question 34
What should you do if the CNC machine stops unexpectedly?
A
Check for error messages
B
Restart the machine immediately
C
Ignore the issue
D
Adjust the spindle speed
Question 35
What is the purpose of a tool presetter?
A
To measure tool dimensions before use
B
To clean the cutting tool
C
To adjust feed rate
D
To inspect the workpiece
Question 36
Which material is commonly machined using CNC?
A
Aluminum
B
Steel
C
Plastic
D
All of the above
Question 37
What is the primary consideration when selecting a cutting tool?
A
Material being machined
B
Spindle speed
C
Coolant type
D
Feed rate
Question 38
Which material property affects machining the most?
A
Hardness
B
Color
C
Density
D
Thermal conductivity
Question 39
What is the purpose of using carbide tools?
A
To machine hard materials
B
To reduce tool wear
C
To improve surface finish
D
All of the above
Question 40
Which material is difficult to machine due to its hardness?
A
Titanium
B
Aluminum
C
Brass
D
Plastic
Question 41
Which industry commonly uses CNC machining for prototyping?
A
Aerospace
B
Automotive
C
Medical
D
All of the above
Question 42
What is the primary advantage of CNC machining over manual machining?
A
Higher precision
B
Faster production
C
Repeatability
D
All of the above
Question 43
Which CNC machine is used for creating complex 3D shapes?
A
CNC mill
B
CNC lathe
C
CNC router
D
CNC plasma cutter
Question 44
What is the purpose of a CNC router?
A
To cut wood, plastic, and soft metals
B
To drill deep holes
C
To create threads
D
To measure tool wear 
Question 45
Which CNC machine is used for cutting sheet metal?
A
CNC plasma cutter
B
CNC lathe
C
CNC mill
D
CNC router
Question 46
What is the formula for calculating cutting speed (SFM)?
A
SFM = (π × Diameter × RPM) / 12
B
SFM = (Diameter × RPM) / 12
C
SFM = (π × Diameter) / RPM
D
SFM = (Diameter × RPM) / π 
Question 47
What is the formula for calculating feed rate (IPM)?
A
IPM = RPM × Number of flutes × Chip load
B
IPM = RPM × Chip load
C
IPM = Number of flutes × Chip load
D
IPM = RPM / Chip load
Question 48
What is the purpose of calculating chip load?
A
To determine feed rate
B
To measure tool wear
C
To adjust spindle speed
D
To calibrate the machine 
Question 49
What is the formula for calculating spindle speed (RPM)?
A
RPM = (SFM × 12) / (π × Diameter)
B
RPM = (SFM × π) / (12 × Diameter)
C
RPM = (SFM × Diameter) / 12
D
RPM = (SFM × 12) / Diameter
Question 50
What is the purpose of calculating tool life?
A
To predict when a tool needs replacement
B
To adjust feed rate
C
To measure workpiece dimensions
D
To calibrate the machine
Once you are finished, click the button below. Any items you have not completed will be marked incorrect. Get Results
There are 50 questions to complete.

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