Glossary Terms

Alloys of iron, carbon and silicon in which more carbon is present than can be retained in austenite. The carbon in excess of austenite solubility in iron precipitates as graphite flakes.

Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.

Powers a grinding wheel or other abrasive tool for the purpose of removing metal and finishing workpieces to close tolerances. Provides smooth, square, parallel and accurate workpiece surfaces. When ultrasmooth surfaces and finishes on the order of microns are required, lapping and honing machines (precision grinders that run abrasives with extremely fine, uniform grits) are used.

Ratio of work material removed to grinding-wheel material lost.

Wheel formed from abrasive material mixed in a suitable matrix. Takes a variety of shapes but falls into two basic categories: one that cuts on its periphery, as in reciprocating grinding, and one that cuts on its side or face, as in tool and cutter grinding.

Specified size of the abrasive particles in grinding wheels and other abrasive tools. Determines metal-removal capability and quality of finish.

Machining grooves and shallow channels. Example: grooving ball-bearing raceways. Typically performed by tools that are capable of light cuts at high feed rates. Imparts high-quality finish.

In cast iron, a permanent increase in dimensions resulting from repeated or prolonged heating at temperatures above 480° C due either to graphitizing of carbides or to oxidation.

Self-guided drill for producing deep holes with good accuracy and fine surface finish. Has coolant passages that deliver coolant to the tool/workpiece interface at high pressure.

Drilling process using a self-guiding tool to produce deep, precise holes. High-pressure coolant is fed to the cutting area, usually through the gundrill’s shank.

Alloy steel produced to specified limits of hardenability. The chemical-composition range may be slightly different from that of the corresponding grade of ordinary alloy steel.

Serrated blade for a manual or power hacksaw that cuts on the forward or return stroke. See sawing.