Glossary

Part of the tool body that remains after the flutes are cut.

Finishing operation in which a loose, fine-grain abrasive in a liquid medium abrades material. Extremely accurate process that corrects minor shape imperfections, refines surface finishes and produces a close fit between mating surfaces.

Light, abrasive material used for finishing a surface.

Intensified, pulsed beams of light generated by lasers—typically carbon dioxide or neodium-doped yttrium aluminum garnet (Nd:YAG)—that drill, weld, engrave, mark, slit and caseharden. Usually under CNC, often at both high cutting rates (100 linear in./sec.) and high power (5kW or more). Lasers also are used in conjunction with in-process quality-control monitoring systems allowing measuring accuracies of 0.00001".

Turning machine capable of sawing, milling, grinding, gear-cutting, drilling, reaming, boring, threading, facing, chamfering, grooving, knurling, spinning, parting, necking, taper-cutting, and cam- and eccentric-cutting, as well as step- and straight-turning. Comes in a variety of forms, ranging from manual to semiautomatic to fully automatic, with major types being engine lathes, turning and contouring lathes, turret lathes and numerical-control lathes. The engine lathe consists of a headstock and spindle, tailstock, bed, carriage (complete with apron) and cross slides. Features include gear- (speed) and feed-selector levers, toolpost, compound rest, lead screw and reversing lead screw, threading dial and rapid-traverse lever. Special lathe types include through-the-spindle, camshaft and crankshaft, brake drum and rotor, spinning and gun-barrel machines. Toolroom and bench lathes are used for precision work; the former for tool-and-die work and similar tasks, the latter for small workpieces (instruments, watches), normally without a power feed. Models are typically designated according to their “swing,” or the largest-diameter workpiece that can be rotated; bed length, or the distance between centers; and horsepower generated. See turning machine.

Cutting tool for lathes and other turning machines. Normally a single-point cutting tool, square in cross section and ground to a shape suitable for the material and task. Intended for simple metal removal, threading, slotting or other internal or external cutting jobs. Clearance to prevent rubbing is provided by grinding back rake, side rake, end relief and side relief, as well as side- and end-cutting edges.

Machining operation in which a workpiece is rotated, while a cutting tool removes material, either externally or internally.

Direction of the predominant surface pattern, which is determined by the production method. See flows; roughness; waviness.

Use of scribers, ink and prick punches to create a part outline that machinists use to visually check part shape during machining of prototypes or during tool-and-die work.

Angle between the side-cutting edge and the projected side of the tool shank or holder, which leads the cutting tool into the workpiece.

Companywide culture of continuous improvement, waste reduction and minimal inventory as practiced by individuals in every aspect of the business.

Functionally the same as a rotary motor in a machine tool, a linear motor can be thought of as a standard permanent-magnet, rotary-style motor slit axially to the center and then peeled back and laid flat. The major advantage of using a linear motor to drive the axis motion is that it eliminates the inefficiency and mechanical variance caused by the ballscrew assembly system used in most CNC machines.

Included angle between a cutter’s tooth and relieved land.

In grinding, the wheel’s tendency to accumulate workpiece material between its abrasive points. In milling, drilling and other operations, excessive packing of chips in cutter flutes or at cutter edge.

CNC feature that evaluates many data blocks ahead of the cutting tool’s location to adjust the machining parameters to prevent gouges. This occurs when the feed rate is too high to stop the cutting tool within the required distance, resulting in an overshoot of the tool’s projected path. Ideally, look-ahead should be dynamic, varying the distance and number of program blocks based on the part profile and the desired feed rate.

Investment-casting process in which a wax pattern is used.

Group of carbon steels designated by American Iron and Steel Institute numerical classification as AISI 1005, 1006, 1008, etc., up to AISI 1026, for a total of 16 grades. They are softer and more ductile than other carbon steels. Composition of low-carbon steels is 0.06 to 0.28 percent carbon, 0.25 to 1.00 percent manganese, 0.040 percent (maximum) phosphorus and 0.050 percent (maximum) sulfur. See high-carbon steels; medium-carbon steels.

Substance that reduces friction between moving machine parts. Can be liquid (hydrocarbon oil), solid (grease) or gaseous (air). Important characteristics are to prevent metal-to-metal contact between moving surfaces, be a cooling medium, aid chip removal and protect surfaces from rust and corrosion.

Measure of the relative efficiency with which a cutting fluid or lubricant reduces friction between surfaces.