CNC Workholding and Fixturing

Question 1

What is the primary purpose of a CNC vise stop (work stop)?

Accepted Answer

To provide a repeatable datum for part positioning

Answer

A work stop provides a consistent reference surface so that each part loaded into the vise starts from the exact same position, ensuring repeatability.

Question 2

When using a machine vise, why should the workpiece be tapped down with a mallet after initial tightening?

Accepted Answer

To seat the part firmly against the parallels and prevent lifting

Answer

Tapping the part down ensures it is fully seated against the parallels, preventing it from lifting due to upward clamping forces during machining.

Question 3

What type of workholding device uses a magnetic field to hold ferrous workpieces without mechanical clamping?

Accepted Answer

Magnetic chuck

Answer

A magnetic chuck uses electromagnetic or permanent magnetic force to hold ferrous (iron-containing) workpieces flat against its surface without obstructing the top.

Question 4

In modular fixturing, what is the primary benefit compared to dedicated fixtures?

Accepted Answer

Reconfigurability for multiple part families without building new fixtures

Answer

Modular fixturing components can be disassembled and reconfigured for different parts, reducing the need to build expensive dedicated fixtures for each job.

Question 5

What is the 3-2-1 locating principle used for in CNC workholding?

Accepted Answer

Constraining all six degrees of freedom with the minimum number of contact points

Answer

The 3-2-1 principle uses three points on the primary plane, two on the secondary, and one on the tertiary to fully constrain a part's six degrees of freedom.

CNC - Cutting Practice Test

CNC - Cutting Practice Test

CNC Workholding and Fixturing