CNC Basics 4

Question 1

What is the role of a 'tool length offset' (TLO) in CNC machining?

Accepted Answer

It compensates for the difference in length between tools so Z-axis moves are accurate

Answer

Tool length offsets tell the controller the actual length of each tool so Z coordinates programmed relative to the workpiece surface remain accurate regardless of which tool is active.

Question 2

Which cutting parameter should be reduced FIRST when machining a thin-walled workpiece to prevent deflection?

Accepted Answer

Radial depth of cut (stepover)

Answer

Reducing radial depth of cut lowers the lateral cutting force that causes thin walls to flex or chatter.

Question 3

What does the CNC term 'dry run' mean?

Accepted Answer

Executing the program at reduced feed with no workpiece installed to verify motion

Answer

A dry run cycles the program at reduced or rapid speed with the workpiece absent to verify the tool path and prevent crashes before actual cutting.

Question 4

When is conventional (up) milling preferred over climb milling?

Accepted Answer

When machining hard, abrasive materials with no backlash in the machine

Answer

Conventional milling is preferred on machines with leadscrew backlash or when cutting hard, abrasive materials where climb milling's tendency to 'grab' could damage the setup.

Question 5

What is the purpose of a 'canned cycle' (e.g., G81, G83) in CNC programming?

Accepted Answer

To simplify repetitive operations like drilling with a single-block command

Answer

Canned cycles condense multi-step operations (rapid approach, feed, retract) into one G-code block, greatly reducing program length for drilling, boring, and tapping.

CNC - Cutting Practice Test

CNC - Cutting Practice Test

CNC Basics 4