Glossary of Machining and Grinding Terms

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Abrasive Belt Grinding - Removal of material from a workpiece with a power-driven, abrasive-coated belt.

Abrasive Belt Polishing - Finishing a workpiece with a power-driven, fine grit, abrasive-coated belt in order to develop a very good finish.

Abrasive Cutoff - Cutting a workpiece through means of a thin, abrasive wheel.

Arbor Milling - The cutting process in which material is removed by a rotating multiple-tooth cutter.

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Boring - Enlarging a hole by removing metal with a single or multi-pointed cutting tool that moves parallel to the axis of the rotation of the workpiece or tool.

Broaching - Cutting with a tool that consists of a bar having a single edge or series of cutting edges (teeth) on its surface. The cutting edges of the multiple tooth or successive, single tooth broaches increase in size and/or change shape. The broach cuts in a straight line relative to the workpiece.

Buffing - Removal of fine scratches or other surface imperfections from a workpiece usually through the use of a very fine abrasive.

Built-Up Edge (BUE) - The pressure welding of piece of work material to the cutting edge of the tool.

Burn - A change in the material caused by the heat of the metalworking operation. Burns are often indicated by localized discoloration.

Burnishing - Smooth surface finishing of a surface by displacement of the material rather than its removal.

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Carbide - A compound of carbon with one or more metallic elements. Often refers to a general class of sintered cutting tools that contain tungsten carbide plus smaller amounts of titanium and tantalum carbide with cobalt acting as the binder.

Cemented Carbide - Carbides that are mixed with cobalt metal powder, milled, and then pressed into the desired shapes and then sintered. Used primarily for cutting tools, dies, and parts subject to heavy abrasive wear.

Centerless Grinding - Process of grinding a cylindrical part between a grinding wheel and a regulating wheel. The grinding wheel abrades away the metal and the regulating wheel controls the speed and horizontal movement of the part. The part is supported underneath by a work rest blade.

Centertype Grinding - External grinding process where a cylindrical part is supported between two pointed metal shafts or centers that are placed in depressions at each end of the workpiece.

Chatter Marks - Flaws on the workpiece surface usually caused by vibrations in the tool and/or workpiece.

Circular Sawing - Using a circular saw fed into a workpiece by motion of either the workpiece of the blade.

Climb Milling - Cutting operation in which the rotation of the cutting tool is in the same direction as the workpiece movement. The chip formed starts out thick and becomes thinner as the tooth progresses through the workpiece.

Counterboring - The removal of material to enlarge a hole with a rotary, pilot-guided, end-cutting tool have two or more cutting edges and usually having flutes for the passage of chips.

Countersinking - Beveling or tapering around the peripheral of a hole creating a concentric surface at an angle less than 90o with the centerline of the hole for the purpose of chamfering holes or recessing screw and rivet heads.

Crater – A depression on the face of the cutting tool caused by wear.

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Deburring - Removal of the burrs or sharp edges from parts by filing, grinding, or rolling the workpiece in a barrel with abrasives. Also called burring.

Drilling - Method of producing a hole using a cutting tool with flutes or grooves spiraling around the drill body that serve as conduit for chip removal.

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End Milling - Milling done with a tool having cutting edges on its cylindrical surface as well as on its end.

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Facing - Generating a flat surface perpendicular to the axis rotation by machining.

Face Milling - Milling of a surface perpendicular to the axis of the cutter.

Finish – Surface quality or appearance.

Finishing - Final machining cuts taken to obtain the desired accuracy and finish.

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G-Ratio - A measure of grinding performance defined as the volume of metal removed divided by the volume of grinding wheel worn away in the process.

Gear Cutting - Producing tooth profiles of equal spacing on the periphery, internal surface, or face of a workpiece through means of an alternate shear gear-form cutter or a gear generator.

Gear Grinding - Removal by grinding of material to obtain correct gear tooth form. One of the more exact methods of finishing gears.

Gear Hobbing - Gear cutting by use of a tool resembling worm gear appearance, having helically spaced cutting teeth. In a single-thread hob, the rows of teeth advance exactly on pitch as the hob makes one revolution.

Gear Milling - Gear cutting with a milling cutter that has been formed to the shape of the tooth space to be cut. The tooth spaces are machined one at a time.

Gear Shaping - Gear cutting with a reciprocating gear-shaped cutter rotating in a mesh with the work blank.

Gear Shaping - Finishing operation performed with a serrated rack or gear-like cutter in a mesh with he gear, but with their axes skewed.

Glazing - The rounding or dulling of the abrasive grain that can promote grinding related problems, such as grinding burn.

Grinding - Material removal through the use of abrasive grains held together by a binder.

Grinding Fluid - A fluid that is applied to a grinding wheel to promote a more efficient grinding operation.

Gun Drilling - Using a drill through which a metalworking fluid is forced at high pressure to flush chips ahead of the tool and back through the flutes for drilling deep holes.

Gun Reaming - Using a multi-lip, end cutting tool through which metalworking fluid is forced at high pressure to flush chips ahead of the tool and back through the flutes for finishing of deep holes.

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Hollow Milling - Using a special end-cutting mill that is designed to leave a core after feeding into or through the workpiece.

Honing - A fine finishing operation using honing stones or sticks containing fine grit/abrasive and oscillating motion that produces accurate dimensions and an excellent finish.

Hot Machining - Machining in which the shear zone on the workpiece is heated by auxiliary means to reduce the shear strength and increase the machinability of the material.

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Indexable Inserts - Inserts with multiple cutting edges that can be rotated to expose the different edges.

Internal Grinding - Grinding the inner diameter of a workpiece by the use a rotating grinding wheel or stones.

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No J entries.

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No K entries.

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Land - The straight section of a cutting tool behind the cutting edge.

Lapping - A fine finishing operation where abrasive slurry is introduced between the workpiece and a lapping tool.

Loading - Pick up of foreign material, often from the workpiece or recirculating fines, in the grinding wheel. Loading often promotes grinding burn and other surface imperfections.

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Machinability - The capability of a material to be machined with relative ease with regards to tool life, surface finish, and power consumption.

Metalworking - A broad term used to refer to the shaping of metal by cutting, grinding, bending, stretching, or stamping.

Metalworking Fluid - A liquid used to cool and/or lubricate the metalworking process.

Milling - Using a rotary tool with one or more teeth that engage the workpiece and remove materials as the workpiece moves past the rotating cutter.

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Nonferrous - Any metal that is not based on iron, such as copper and aluminum.

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OD Grinding - An external grinding operation to reduce the Outer Diameter of a cylindrical part.

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Planing - Producing flat surfaces by linear reciprocal motion of the workpiece and the table to which it is attached relative to a stationary, single-point cutting tool.

Polishing - Removal of metal by the action of abrasive grains to obtain a fine finish. Usually, performed with a fine grit abrasive wheel or belt.

Power Band Sawing - Using a long, multiple-tooth continuous band (band saw) in a uniform cutting action as the workpiece is fed into the saw.

Power Hack Sawing - Sawing that occurs when feeding a workpiece into a reciprocating, powered saw blade.

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Quenched - Rapid cooling of metals by liquids, gases, or air.

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Ra - The average roughness of a surface that is calculated as the mean of absolute values of the distance between the baseline to the maximum peak or valley height.

Rake, Negative - The face of the tool along which the chip travel is inclined forward from the cutting edge forming a greater than 90^o angle with the freshly cut surface. A negative rake angle is useful in machining high-strength materials in order to reduce chipping of the tool.

Rake, Positive - The face of the tool along which the chip travel is inclined backward from the cutting edge forming a less than 90^o angle with the freshly cut surface.

Rake Angle - The angle between the tool face and an imaginary line perpendicular to the freshly cut surface.

Reaming - Operation in which a previously formed hole is sized and contoured accurately by using a rotary cutting tool (reamer) with one or more cutting elements (teeth). The main support for the reamer during the cutting action is obtained from the workpiece.

Rockwell - An indentation-type hardness test which uses a variety of indentors and loads.

Roughing - Machining without consideration for surface finish.

Routing - Cutting out and contouring edges of various shapes in a relatively thin material using a small diameter rotating cutter that is operated at high speeds.

Rust - A form of ferrous corrosion.

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Sawing - A multi-point cutting process in which the workpiece is advanced into a moving continuous band that has teeth along one edge.

Shank - Portion of the tool by which it is held, such as the shank of the drill that is held in a chuck.

Side and Slot Milling - Milling the side or slot of a workpiece using a peripheral cutter.

Skewness - The relative comparison of peaks and valleys of a surface. If the peaks are higher than the valleys are deep, the surface has a positive skew. If the valleys are deeper than the peaks are high, the surface has a negative skew.

Slap Milling - Milling of a surface parallel to the axis of a helical, multiple-toothed cutter mounted on an arbor.

Snagging - Heavy stock removal of superfluous material from a workpiece by using a portable or swing grinder mounted with a coarse grain, grinding wheel.

Specific Metal Removal Rate (Q') - The volume of metal removed per unit of time per unit of effective grinding wheel width.

Spindle - Rotating shaft for tool holders.

Spotfacing - Using a rotary, hole-piloted, end-facing tool to make a flat surface normal to the axis of rotation of the tool on or slightly below the workpiece surface.

Stradle Milling - Peripheral milling a workpiece on both sides at once using two spaced cutters.

Super Finishing - An abrasive process using either a bonded stock for a cylindrical workpiece or a cup wheel for flat or spherical work. A large contact area, approximately 30%, exists between the workpiece and the abrasive. Superfinishing removes small imperfections, such as grinding feed marks and grinding chatter marks.

Surface Finish (roughness) - Fine irregularities measured in terms of height and spacing.

Surface Grinding - Producing a flat surface with a rotating grinding wheel as the workpiece passes under the wheel

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Tapping - A method used to cut or form threads inside a predrilled hole.

Thread Grinding - Thread cutting through the use of a suitably formed grinding wheel.

Thread Rolling - A process that uses dies and pressure to roll threads on a part. Metal is only moved in this operation. No metal is removed.

Thread Tapping - A process that uses a tapping tool to place internal threads in a part.

Threading - Producing external threads on a cylindrical surface.

Tolerance - Permissible variation in the dimension of a part.

Tool Life - A measure of the length of time a tool will cut satisfactorily.

Trepanning - Cutting with a boring bar tool that is designed to leave an unmatched core when the operation is finished.

Turning - Generating cylindrical forms by removing metal with a single-point, cutting tool that moves parallel to the axis of the rotation of the workpiece. Performed on turning centers and lathes.

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Up Milling - Opposite of climb/down milling. The cutting tool rotates against the direction in which the workpiece is fed. The chip starts out thin and gets thicker as the cut progresses.

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No V entries.

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Waviness - A surface finish that involves irregular, long-range deviations. Tool chatter, spindle eccentricity, or other unintended motions of the cutting tool or machinery usually cause waviness.

Wear - Loss of material from a surface due to rubbing.

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No Y or Z entries.