Meeting the workholding challenge: Turning Performance

In my August column, I described several common applications for workholding when turning, where the cutting tool is static and the workpiece spins. There are several standard workholders for turning, which were illustrated.

However, for clamped parts that are cut with a rotating tool, or parts held in position for specific processes, such as welding or broaching, many workholding applications are custom; you could probably create an encyclopedia with examples of workholders designed and built for specific parts. These unique workholding methods are often required to ensure part integrity is the same coming out as it was going in.

In addition, workholder intricacy varies. Workholding for milling machines can be as simple as clamps on a table or as complex as a hydraulically plumbed behemoth weighing thousands of pounds. Workholding for stamping presses comes from the die tool itself, which must support the tons of pressure applied to the material to achieve the desired form.

Other types of workholding for static parts require different approaches. For example:

• Broach fixtures require self-aligning features in order to correctly remove metal in a shearing motion.
• Workholders for weld cells require space to allow the welder to move between the weld points and weld at the correct angle.
• Assembly machines must hold parts accurately so other programmed motions are executed correctly.

The science behind any workholding technique is based on locating techniques outlined in my previous columns. The form may change, but the principles remain the same.