Fixturing (Workholding)

Fixturing encompasses the devices, clamps, and setup methods used to securely hold and precisely position a workpiece on the machine table during machining, a critical factor in achieving dimensional accuracy and repeatability. Poor fixturing allows part movement during cutting forces, resulting in dimensional errors, deflection, chatter, and part damage, while over-clamping can distort thin-walled parts or create marking where clamps contact the surface.

Professional machine shops invest in modular fixturing systems with precision parallels, clamps, and locating pins that enable quick setup and repeatable positioning of parts within tight tolerances. Programmers design tool paths with fixturing in mind, avoiding tool-clamp collisions and planning multi-setup parts so that clamps don't obstruct access to critical surfaces.

The relationship between part geometry, cutting forces, and clamping strategy is so important that many shops have dedicated fixturing engineers who analyze new parts and design specialized fixtures to ensure both safety and dimensional accuracy throughout the CNC machining process.