CNC CNC Lathe Turning Operations 2 — Questions and Answers
Question 1: Which G-code cancels canned cycle operation on a CNC lathe?
- G04
- G80 (Correct answer)
- G98
- G28
Correct answer: G80
G80 cancels any active canned cycle, returning the lathe to normal operation mode.
Question 2: What does the term 'chatter' describe in CNC lathe turning?
- Vibration causing poor surface finish (Correct answer)
- Rapid spindle direction changes
- Chip breakage pattern
- Feed rate fluctuation
Correct answer: Vibration causing poor surface finish
Chatter is a resonant vibration between the cutting tool and workpiece that produces a poor, wavy surface finish.
Question 3: When turning a taper using the compound rest method, the compound is set to:
- The full included angle
- Half the included angle (Correct answer)
- The taper per foot value
- The taper per inch value
Correct answer: Half the included angle
The compound rest is swiveled to half the included taper angle because it moves along one side of the taper.
Question 4: In G-code, the M03 command with an S-word sets the spindle to:
- Reverse rotation at specified RPM
- Forward rotation at specified RPM (Correct answer)
- Spindle stop
- Spindle speed override
Correct answer: Forward rotation at specified RPM
M03 starts the spindle in the forward (clockwise) direction at the RPM specified by the S-word.
Question 5: What is the purpose of a steady rest in CNC lathe operations?
- To increase cutting speed
- To support long slender workpieces during turning (Correct answer)
- To hold the cutting tool rigidly
- To adjust spindle speed automatically
Correct answer: To support long slender workpieces during turning
A steady rest supports long, slender workpieces midspan to prevent deflection and vibration during turning.
Question 6: What does 'nose radius compensation' on an insert affect?
- Spindle speed calculation
- Actual part geometry when turning tapers and radii (Correct answer)
- Tool change position
- Coolant flow rate
Correct answer: Actual part geometry when turning tapers and radii
Nose radius compensation (G41/G42) offsets the programmed path to account for the insert tip radius so tapers and profiles are cut accurately.
Question 7: Which cutting condition most directly increases tool life when turning stainless steel?
- Increasing depth of cut
- Reducing cutting speed (Correct answer)
- Eliminating coolant
- Using a larger nose radius
Correct answer: Reducing cutting speed
Reducing cutting speed lowers heat generation at the tool-chip interface, which is the primary cause of rapid tool wear in stainless steel.
CNC CNC Lathe Turning Operations 2
Which G-code cancels canned cycle operation on a CNC lathe?