Machine Glossary

What the words in machine ads actually mean, in plain language.

3-axis / 4-axis / 5-axis: How many directions a CNC machine can move the tool or the job. A 3-axis machine moves in X, Y and Z. A 4th axis rotates the job, and a 5th tilts it, so complex parts can be cut in one setup.
ATC (Automatic Tool Changer): A system that swaps cutting tools without the operator stopping the machine. Common on machining centres and higher-end CNC routers.
Backlash: Play or looseness in an axis when it changes direction. High backlash on a used machine means worn screws or nuts and poor accuracy.
Ball screw: A precision screw that turns motor rotation into smooth, accurate linear movement. Worn ball screws are one of the main costs in reconditioning a machine.
Bed size / working area: The largest sheet or job the machine can cut, usually given in feet (4x8, 5x10) or millimetres.
CFM: Cubic feet per minute. The volume of air a compressor delivers. Check the CFM your tools need, not just the tank size.
Chiller: A water cooling unit that keeps a laser tube, laser source or spindle at a steady temperature. CO2 and fiber lasers need one to run safely.
CNC: Computer Numerical Control. The machine follows a program instead of an operator's hands, so it can repeat the same cut accurately again and again.
CO2 laser: A laser that uses a gas-filled glass tube. Best for cutting and engraving wood, acrylic, MDF, leather and fabric.
Controller: The computer that runs the machine, such as Fanuc, Siemens, Mitsubishi, DSP or Mach3. Parts and repair support differ a lot between brands.
DSP controller: A handheld or panel controller used on many Chinese CNC routers. It runs files from a USB stick without a PC.
EDM: Electrical Discharge Machining. Cuts hard metals with electric sparks. Wire EDM cuts shapes with a thin wire; sinker EDM burns a shaped electrode into the job.
Fiber laser: A solid-state laser that cuts metal sheet fast and with little upkeep. Power is given in watts or kilowatts (1kW, 3kW, 6kW).
G-code: The programming language most CNC machines read. CAM software turns your drawing into G-code.
KVA: Kilovolt-amperes. The size of a generator or transformer. Pick a KVA rating above the total starting load of your machines.
Linear guide: Rails and blocks that carry each axis. Square rail guides are stiffer and more accurate than round rails.
Plasma cutter: Cuts steel, stainless and aluminium with a jet of hot plasma. Cheaper than a fiber laser for thick plate, with a rougher edge.
Reconditioned / refurbished: A used machine that a dealer has repaired, replaced worn parts on, repainted and tested before sale.
RPM: Revolutions per minute. How fast the spindle turns. Wood and plastic need high RPM; metal cutting needs more torque at lower RPM.
Servo motor: A motor with feedback that reports its position. Faster and more accurate than a stepper, and does not lose steps under load.
Spindle: The motor that spins the cutting tool. Given in kW (for example 3.2kW or 5.5kW), with air or water cooling.
Stepper motor: A cheaper motor that moves in fixed steps without position feedback. Common on entry-level routers and lasers.
Tonnage: The clamping force of an injection molding machine or press, in tons. Bigger parts need more tonnage.
VMC: Vertical Machining Centre. A CNC milling machine with a vertical spindle, usually with an ATC and an enclosed cabin.

Want to go deeper? Read our machine buying guides.