Work Holding & Fixturing Flashcards
7 cards from real CNC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Work Holding & Fixturing flashcards as text
What is the function of a floating jaw (compensating jaw) in a CNC vise?
Answer: To self-adjust and distribute clamping force evenly on non-parallel workpiece faces
A floating or compensating jaw pivots slightly to make full contact with both sides of a non-parallel or irregular workpiece, preventing rocking.
A cam-lock fixture is characterized by its ability to:
Answer: Quickly clamp and release a workpiece with a 90-degree handle rotation
Cam-lock clamps convert a partial rotation of a cam into a secure clamping action, enabling fast loading and unloading of workpieces.
When a workpiece is clamped in a four-jaw independent lathe chuck on a CNC turning center, the primary advantage over a three-jaw chuck is:
Answer: The ability to indicate and center non-round or eccentric workpieces
Each jaw of a four-jaw chuck adjusts independently, allowing precise centering of irregular parts or intentional eccentricity.
What is the purpose of a fixture plate (also called a sub-plate or tooling plate)?
Answer: To provide a repeatable, pre-drilled mounting surface for quick fixture changes
A tooling plate with precision-bored holes and threaded inserts allows fixtures and clamps to be mounted quickly and repositioned accurately.
In CNC milling, workpiece 'lift-off' during a climb milling pass is most commonly prevented by:
Answer: Ensuring clamps are positioned over the supported areas of the workpiece
Positioning clamps directly over the support points (parallels, stop pins) counters the upward cutting force and prevents part lifting.
A 'riser block' is used in CNC fixturing to:
Answer: Increase vise jaw height to accommodate taller workpieces
Riser blocks bolt between the vise base and the machine table, raising the vise so that taller workpieces can be gripped properly.
Which best explains why soft jaws are used in CNC production machining?
Answer: They can be machined to match the exact contour of a finished or delicate workpiece
Soft jaws are made from aluminum or mild steel and can be bored or milled to conform precisely to the workpiece shape, distributing clamping load and preventing marring.