Glossary

Smoothing and shining a surface by pressing an abrasive compound, embedded in a soft wheel or belt, against the workpiece.

1. Flexible portion of a bandsaw blade. 2. Support material behind the cutting edge of a tool. 3. Base material for coated abrasives.

Reaction in dynamic motion systems where potential energy that was created while the object was in motion is released when the object stops. Release of this potential energy or inertia causes the device to quickly snap backward relative to the last direction of motion. Backlash can cause a system’s final resting position to be different from what was intended and from where the control system intended to stop the device.

Rapid withdrawal of the tool from the workpiece.

Support that mounts on a cylindrical grinder to prevent deflection when grinding long, small-diameter stock.

Additive to cutting fluids to inhibit bacterial growth. See fungicide.

1. Heating to a low temperature to remove gases. 2. Curing or hardening surface coatings, such as paints, by exposure to heat. 3. Heating to drive off moisture, as in the baking of sand cores after molding. Often used after plating or welding, or when the presence of hydrogen is suspected, to prevent embrittlement.

Variation of bandsawing that uses an abrasive band to polish parts previously sawed or filed. See bandsawing.

Machine that utilizes an endless band, normally with serrated teeth, for cutoff or contour sawing. See saw, sawing machine.

Endless band, normally with serrated teeth, that serves as the cutting tool for cutoff or contour band machines.

Long, endless band with many small teeth traveling over two or more wheels (one is a driven wheel, and the others are idlers) in one direction. The band, with only a portion exposed, produces a continuous and uniform cutting action with evenly distributed low, individual tooth loads. Often called band machining.

Mass finishing process that involves low-pressure abrasion resulting from tumbling workpieces in a barrel (usually of hexagonal or octagonal cross section) together with an abrasive slurry. See finishing.

Test for determining relative ductility of metal that is to be formed (usually sheet, strip, plate or wire) and for determining soundness and toughness of metal (after welding, for example). The specimen is usually bent over a specified diameter through a specified angle for a specified number of cycles.

Black finish on a metal produced by immersing it in hot oxidizing salts or salt solutions.

Hole or cavity cut in a solid shape that does not connect with other holes or exit through the workpiece.

Workholding devices used on milling machines. Styles include step, finger-holding, telescoping and quick-clamp.

Brittleness exhibited by some steels after being heated to a temperature within the range of about 200° C to 370° C, particularly if the steel is worked at the elevated temperature.

Abrasive grains mixed with a bonding agent. The mixture is pressed to shape and then fired in a kiln or cured. Forms include wheels, segments and cup wheels. Bond types include oxychloride, vitrified, silicate, metal, resin, plastic, rubber and shellac. Another type of bond is electroplated, wherein the abrasive grains are attached to a backing by a thick layer of electroplated material.

Command that allows the addition, subtraction or intersection of solid objects in CAD.

Enlarging a hole that already has been drilled or cored. Generally, it is an operation of truing the previously drilled hole with a single-point, lathe-type tool. Boring is essentially internal turning, in that usually a single-point cutting tool forms the internal shape. Some tools are available with two cutting edges to balance cutting forces.

Essentially a cantilever beam that holds one or more cutting tools in position during a boring operation. Can be held stationary and moved axially while the workpiece revolves around it, or revolved and moved axially while the workpiece is held stationary, or a combination of these actions. Installed on milling, drilling and boring machines, as well as lathes and machining centers.

Cutting tool mounted in a boring bar (the holder) that enlarges a cored or drilled hole. May be a single-point or multiple-cutting-edge tool. Can be adjustable.

Single- or multiple-point precision tool used to bring an existing hole within dimensional tolerance. The head attaches to a standard toolholder and a mechanism permits fine adjustments to be made to the head within a diameter range.

Similar to a turning machine except that the cutting tool (single-point or multiple-cutting-edge), rather than the workpiece, rotates to perform internal cuts. However, boring can be accomplished by holding the tool stationary and turning the workpiece. Takes a variety of vertical, slanted and horizontal forms, and has one or more spindles. Typically a large, powerful machine, it can readily hold tolerances to 0.0001". See jig boring; lathe; turning machine.

Sulfur, chlorine, phosphorus and other compounds added to cutting fluids to fill in surface irregularities at the tool/workpiece interface, creating a lubricating film. See cutting fluid; lubricity.

Number related to the applied load (usually, 500 kgf and 3,000 kgf) and to the surface area of the permanent impression made by a 10mm ball indenter. The Brinell hardness number is a calculated value of the applied load (kgf) divided by the surface area of the indentation (mm2). Therefore, the unit of measure of a Brinell hardness number is kgf/mm2, but it is always omitted.

Test for determining the hardness of a material by forcing a hardened steel or carbide ball of specified diameter into the material under a specified load. The result is expressed as the Brinell hardness number. See Knoop hardness test; Rockwell standard hardness test; Rockwell superficial hardness test; Scleroscope hardness test; and Vickers hardness test.

Separation of a solid accompanied by little or no macroscopic plastic deformation. Typically, brittle fracture occurs by rapid crack propagation with less expenditure of energy than for ductile fracture.

Tapered tool, with a series of teeth of increasing length, that is pushed or pulled into a workpiece, successively removing small amounts of metal to enlarge a hole, slot or other opening to final size.

Operation in which a cutter progressively enlarges a slot or hole or shapes a workpiece exterior. Low teeth start the cut, intermediate teeth remove the majority of the material and high teeth finish the task. Broaching can be a one-step operation, as opposed to milling and slotting, which require repeated passes. Typically, however, broaching also involves multiple passes.

Machine designed specifically to run broaching tools. It is typically designated by operating characteristics (pull, push, rotary, continuous, blind-spline), type of power used (hydraulic, mechanical) and tonnage ratings. Broaching is also performed on arbor presses (manual and powered).

Generic term for a curve whose shape is controlled by a combination of its control points and knots (parameter values). The placement of the control points is controlled by an application-specific combination of order, tangency constraints and curvature requirements. See NURBS, nonuniform rational B-splines.

Use of rapidly spinning wires or fibers to effectively and economically remove burrs, scratches and similar mechanical imperfections from precision and highly stressed components. The greatest application is in the manufacture of gears and bearing races where the removal of sharp edges and stress risers by power methods has increased the speed of the operation.

1. Permanently damaging a metal by heating to cause either incipient melting or intergranular oxidation. 2. In grinding, getting the workpiece hot enough to cause discoloration or to change the microstructure by tempering or hardening.

Tool-condition problem characterized by the adhesion of small particles of workpiece material to the cutting edge during chip removal.

Rotary tool that removes hard or soft materials similar to a rotary file. A bur’s teeth, or flutes, have a negative rake.

Finishing method by means of compressing or cold-working the workpiece surface with carbide rollers called burnishing rolls or burnishers.

Stringy portions of material formed on workpiece edges during machining. Often sharp. Can be removed with hand files, abrasive wheels or belts, wire wheels, abrasive-fiber brushes, waterjet equipment or other methods.

Cylindrical sleeve, typically made from high-grade tool steel, inserted into a jig fixture to guide cutting tools. There are three main types: renewable, used in liners that in turn are installed in the jig; press-fit, installed directly in the jig for short production runs; and liner (or master), installed permanently in a jig to receive renewable bushing.

Round insert that is able to spread the stresses generated by the cutting forces over a larger area than other insert shapes. However, a round insert generates higher axial forces, which transfer into the workpiece.