CNC Workholding and Fixturing 2

Question 1

What is the function of a toe clamp in CNC fixturing?

Accepted Answer

To hold the workpiece from above by stepping over its edge

Answer

Toe clamps step over the edge of a workpiece and apply downward clamping force from above, holding the part to the table or fixture plate.

Question 2

Which type of chuck jaw is used when machining a second operation (Op 2) that must be centered on a previously machined bore?

Accepted Answer

Soft bored jaws

Answer

Soft bored jaws are bored to match the part's previously machined diameter, providing precise centering and even clamping force for Op 2 machining.

Question 3

What is a major advantage of using a zero-point clamping system in CNC machining?

Accepted Answer

Allows sub-minute workpiece changes with pre-set repeatability

Answer

Zero-point clamping systems allow palletized workpieces or fixtures to be located and clamped within seconds with repeatability under 0.005mm.

Question 4

When clamping a thin, flat workpiece on a CNC mill table, why is vacuum fixturing preferred?

Accepted Answer

It holds the part without deforming it and keeps the top surface clear

Answer

Vacuum fixturing applies uniform distributed force across the part's bottom surface, preventing distortion of thin parts while keeping the entire top surface accessible.

Question 5

In CNC turning, why is it critical that the cutting tool is set exactly at center height?

Accepted Answer

To prevent rubbing on the tool flank and ensure correct cutting geometry

Answer

When the tool is not at center height, the effective rake and clearance angles change, causing rubbing rather than cutting, increased forces, and poor surface finish.

CNC - Cutting Practice Test

CNC - Cutting Practice Test

CNC Workholding and Fixturing 2