Glossary Terms

Sawing process that uses the back-and-forth motion of a short, straight-toothed blade to cut the workpiece. Hacksawing machines are generally electrically driven and may or may not provide for application of cutting fluid to the saw blade or workpiece.

Machining and measuring to exacting standards. Four basic considerations are: dimensions, or geometrical characteristics such as lengths, angles and diameters of which the sizes are numerically specified; limits, or the maximum and minimum sizes permissible for a specified dimension; tolerances, or the total permissible variations in size; and allowances, or the prescribed differences in dimensions between mating parts.

Heating before some further thermal or mechanical treatment.

Discipline based on the likelihood of any given event happening; mathematical techniques built around sampling methods, combinations and permutations. Key to understanding statistical-process-control systems. See SPC, statistical process control.

Imprecise term denoting various treatments used to improve workability. For the term to be meaningful, the condition of the material and the time-temperature cycle used must be stated.

Method of monitoring a process. Relates to electronic hardware and instrumentation used in automated process control. See in-process gaging, inspection; SPC, statistical process control.

Measure of the efficiency with which human and material resources are used to produce goods and services. Output per man-hour has traditionally been the most stable measure, but, since direct labor is sharply reduced by CAD, CAM and computer-integrated manufacturing, alternative methods of measuring may be more accurate.

Machining vertical edges of workpieces having irregular contours; normally performed with an endmill in a vertical spindle on a milling machine or with a profiler, following a pattern. See mill, milling machine.

Terms denoting a formal program for monitoring product quality. The denotations are the same, but QC typically connotes a more traditional postmachining inspection system, while QA implies a more comprehensive approach, with emphasis on “total quality,” broad quality principles, statistical process control and other statistical methods.

Fracture of a metal during quenching. Most frequently observed in hardened carbon steel, alloy steel or tool steel parts of high hardness and low toughness. Cracks often emanate from fillets, holes, corners or other stress raisers and result from high stresses due to the volume changes accompanying transformation to martensite.

1. Hardening alpha-beta alloys (most often copper or titanium alloys) by solution-treating and quenching to develop a martensite-like structure. 2. In ferrous alloys, hardening by austenitizing and then cooling so that austenite transforms to martensite.

Rapid cooling of the workpiece with an air, gas, liquid or solid medium. When applicable, more specific terms should be used to identify the quenching medium, the process and the cooling rate.