- ATC (automatic tool changer)
- The mechanism that swaps tools between the spindle and a tool magazine. A listing's "tool capacity" (for example, "30 ATC") is the number of tool pockets, which sets how many tools stay loaded between jobs.
- 4th axis, 5th axis
- Extra rotary axes added to the three linear axes of a mill, usually through a rotary table or trunnion. They let the machine reach more faces of a part in one setup.
- B-axis
- A rotary axis that tilts a head or spindle, as on a mill-turn machine's milling spindle or on a horizontal machining center's rotary table. It brings angled features and several faces of the part into reach.
- Backlash
- Lost motion when an axis reverses direction, caused by clearance in the ballscrew, nut or drive. Large or uneven backlash points to wear.
- Ballscrew
- The precision screw that turns a motor's rotation into linear axis motion. Wear shows up as backlash and as loss of accuracy.
- BT, CAT (spindle tapers)
- Standards for the tapered holder in a machining spindle. CAT is the American standard and BT the Japanese one. The number (30, 40, 50) is the taper size: larger numbers suit heavier cutting. CAT and BT holders look alike but are not interchangeable. A "CAT40" spindle takes CAT40 holders; a "BT30" spindle takes BT30 holders.
- C-axis
- On a lathe, the ability to control the spindle's rotation as an axis. With live tooling it allows milling and drilling at set angles.
- Chip conveyor, chip auger
- Systems that carry cutting chips out of the machine. A conveyor or auger saves time and cleanup.
- CNC
- Computer numerical control: a machine whose movements are driven by a program run by a computer control.
- Control
- The computer and operator panel that runs the machine. Examples in our listings include Haas, Fadal 88HS, Mitsubishi, Mazatrol and Yasnac. The control decides which programs, software and support you can use.
- DRO (digital readout)
- A display of axis positions on a manual machine, such as a Bridgeport mill.
- EDM, wire EDM
- Electrical discharge machining: material is removed by controlled sparks. Wire EDM cuts with a thin wire and is used for tight-tolerance profiles in hardened material.
- HMC (horizontal machining center)
- A machining center with a horizontal spindle, usually with pallets and a rotary axis. Common in production work.
- Live tooling
- Powered tools mounted in a lathe's turret, which let a lathe mill, drill and tap as well as turn.
- Mill-turn
- A turning center that also has a milling spindle, and often a second spindle, so a complex part can be finished in one setup.
- Pallet changer
- A system that swaps work between a loading station and the machine, so one part can be loaded while another is machining.
- Probing (touch probe)
- A sensing device that measures a part or a tool inside the machine, used for setup and inspection. Renishaw is a common brand.
- Rapid traverse
- The fastest speed an axis moves when it isn't cutting. Listings show it in inches per minute (IPM).
- Rigid tapping
- A control feature that synchronizes spindle rotation and Z-axis movement so threads can be tapped with a solid holder instead of a floating one.
- RS-232
- A serial port used to send programs to and from older controls.
- Spindle nose (A2-6, A2-11, D1-4)
- The standard used to mount a chuck on a lathe spindle. It decides which chucks fit.
- Spindle chiller
- A cooling unit that holds the spindle at a stable temperature, which helps accuracy and spindle life.
- TSC (through-spindle coolant)
- Coolant delivered through the spindle and the tool at pressure (for example, 1,000 PSI), which clears chips from deep holes and extends tool life.
- Tombstone
- A vertical fixture column on a horizontal machine's pallet that holds parts on several faces.
- Travels (X, Y, Z)
- How far each axis moves. They set the biggest part the machine can reach.
- VDI (VDI30, VDI40)
- A standard for lathe turret tool holders. The number is the shank size. Holders must match the turret's VDI size and mounting style.
- VMC (vertical machining center)
- A machining center with a vertical spindle. The most common machine in job shops.
- Work envelope
- The volume a machine can reach, set by its travels and, on a lathe, its swing and turning length.
- 5C collet, 5C indexer
- A common collet size for holding round, hex and square bar stock. A 5C indexer is a rotary head that holds 5C collets and rotates the work to set angles.
Glossary
CNC machine glossary: the terms in used-machine listings, explained
Used-machine listings are full of abbreviations. Here is what they mean and why they matter when you compare machines.
See them in context
Browse machines with full specs.
Every listing shows its travels, spindle, taper, tool capacity and included items.