Workholding and Fixturing Flashcards

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

Answer: To hold the workpiece from above by stepping over its edge

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.

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

Answer: Soft bored jaws

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

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

Answer: Allows sub-minute workpiece changes with pre-set repeatability

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

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

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

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

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

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

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.

What is the purpose of using strap clamps with step blocks in CNC milling setups?

Answer: To apply downward clamping force to odd-shaped or large workpieces

Strap clamps with step blocks provide versatile downward clamping for irregularly shaped or large parts that cannot fit in a standard vise.