Workholding: Workholding is the way a part is held still and located on a machine while it is cut, using vices, chucks, clamps, vacuum tables or custom fixtures.
Every cut pushes on the part, so it must be gripped firmly and in a known position. Mills use vices, clamps, vacuum tables and soft jaws machined to the part’s shape; lathes use chucks and collets. The holding method also decides which faces the tool can reach before the part has to be turned over and clamped again.
What it means for the price
Workholding drives setup cost. A rectangular block in a standard vice is quick to set up. An organic shape may need soft jaws or a fixture made first, and thin parts may need special support to stop vibration and distortion. Every re-clamp to reach another face adds a setup, which is why a part with features on many faces costs more than its cutting time suggests.
Example: machining soft jaws for an awkward part can add 45 minutes to the first setup. A batch of ten shares that time; a one-off pays it alone. The figures are an example.
Common confusions
Workholding is the general term; a fixture is one kind of it, made for a specific part. A vice is workholding but not a fixture. On a 3-axis machine the number of clampings usually equals the number of setups. Read how CNC setup time affects price.
Go deeper: Set-up time in CNC: the hidden cost in small batches