Glossary Terms

Device for cutting face, peripheral or cylindrical cams from flat cam-former stock.

Subroutine or full set of programmed NC or CNC steps initiated by a single command. Operations are done in a set order; the beginning condition is returned to when the cycle is completed. See CNC, computer numerical control; NC, numerical control.

Compound of carbon and one or more metallic elements. For cutting tools, tungsten carbide, titanium carbide, tantalum carbide or a combination of these in a cobalt or nickel matrix provides hardness, wear resistance and heat resistance. Other elements added to carbide include vanadium, niobium, silicon, boron and hafnium.

Known as unalloyed steels and plain carbon steels. Contains, in addition to iron and carbon, manganese, phosphorus and sulfur. Characterized as low carbon, medium carbon, high carbon and free machining.

Casehardening metal by heating it in a mixture of carbon and nitrogen and by controlling the cooling rate. Allows carbon to enter the surface microstructure.

Absorption and diffusion of carbon into solid ferrous alloys by heating, to a temperature above the transformation range, in contact with a suitable carbonaceous material. A form of casehardening that produces a carbon gradient extending inward from the surface, enabling the surface layer to be hardened either by quenching directly from the carburizing temperature or by cooling to room temperature, then reaustenitizing and quenching.

Mechanical device placed on the lathe head or ways to prevent over-travel that might damage the machine or workpiece.

Generic term covering several processes applicable to steel that change the chemical composition of the surface layer by absorption of carbon, nitrogen or a mixture of the two and, by diffusion, create a concentration gradient. Processes commonly used are carburizing, quench hardening, cyaniding, nitriding and carbonitriding.

Alloys cast from the molten state. Most high-speed steel is melted in an electric-arc furnace and cast into ingots.

Used as wear-resistant (largest application area), corrosion-resistant and heat-resistant materials. They have different names depending on the manufacturers, such as Stellite, Tribaloy, Haynes alloys and MP35N. These alloys are hard, brittle and difficult to use for making cutting tools.

Cast ferrous alloys containing carbon in excess of solubility in austenite that exists in the alloy at the eutectic temperature. Cast irons include gray cast iron, white cast iron, malleable cast iron and ductile, or nodular, cast iron. The word “cast” is often left out.

Machining entirely within the body of a workpiece.