Cutting Processes 111

band saw

A saw that uses a flexible blade constructed from a continuous loop or band of metal. Band saws can be used to produce rough cuts and separate stock for additional processing.

bed

The main supporting structure upon which the operating parts of a machine are mounted and guided. Beds provide a foundation for various machine tools.

beveled

Angled in comparison to the major surfaces of a part. Beveled surfaces are created during chamfering.

boring

The use of a single-point cutting tool to enlarge an existing hole. Boring can be done on either a lathe or a mill, and it helps create a hole that is concentric and that meets tight tolerances.

burrs

A sharp, unwanted bit of material remaining on an edge after machining. Burrs can potentially cut individuals and often interfere with assembly.

cast iron

A metal that consists of iron, over 2.11% carbon, and 1 to 3% silicon and that offers heat resistance and compressive strength. Cast iron is often used as a machine base material because it dampens vibration.

centerline

An imaginary line that divides a shape into two equal halves or that runs through the center of a cylindrical object. On a lathe, a drill machines a hole on the centerline of a workpiece.

chamfering

Machining a small angled feature along a part edge. Chamfering helps remove burrs and aids in part assembly.

chips

An unwanted piece of material that is removed from a workpiece. Chips are formed when a tool cuts or grinds a workpiece.

chuck

A general term for standard workholding devices used to clamp a workpiece. Chucks are used to hold cylindrical parts on the lathe.

clearance

An intentional amount of space left between two components. Clearance helps ensure two parts can move freely or ensures there is no contact between two surfaces.

column

The rigid, vertical support section of the machine. Columns suspend components and tools over the workpiece as well as support them.

composite

A material made from combining two materials from the separate groups of polymers, metals, and ceramics. In a composite, all the materials retain their respective characteristics.

computer numerical control

CNC. The use of a computer and special programs to carry out various manufacturing operations. Computer numerical control can be run both lathes and mills used to machine parts.

concentric

Having a common center or sharing the same axis with another object. If a smaller circle is concentric to a larger circle, it fits perfectly inside the larger circle.

contour milling

Milling that requires non-linear tool movement along two or more axes at the same time to produce a curved surface feature. Contour milling creates complex shapes.

cutoff

An operation performed on the lathe that uses a cutting tool to separate a finished part from the rest of the stock. A cutoff operation is often the last step on the lathe.

cutting edge

The edge of a cutting tool that engages the workpiece material and removes material in the form of chips. A tool may have a single edge or multiple cutting edges.

cutting tool

A tool with one or more cutting edges designed to engage a workpiece and remove material in the form of chips. Cutting tools ideally exhibit excellent hardness, toughness and wear resistance.

deflecting

The unintended movement or repositioning of a cutting tool or component due to a mechanical force. Deflection, or walking, of a cutting tool can cause poor surface finish and inaccurate dimensions.

drill

A multi-point tool used to penetrate the surface of a workpiece. Drills are most frequently used to make round holes.

drill press

A machine tool that is used for a range of holemaking operations such as drilling, reaming, and tapping. A drill press is limited to only vertical motion of the spindle in order to feed the cutting tool into the workpiece.

drilling

Using a multi-point tool to machine a new round hole into the surface of a workpiece. Drilling can be done on a drill press, lathe, or mill.

end mill

A milling cutter that can be used for both peripheral and face milling. End mills engage the bottom and edges of the milling cutter.

end milling

A milling operation that uses a narrow cutter to machine surfaces both parallel and perpendicular to the spindle axis. End milling may cut with both the bottom and sides of the cutting tool.

face mill

A flat mill cutter with multiple cutting teeth on the periphery of the tool. The bottom of the face mill is the primary cutting surface during face milling operations.

face milling

A milling operation involving a relatively wide cutter that removes material from the part to produce a flat surface. Face milling is typically done to establish the part's height on the mill.

facing

A turning operation that removes material from the end of the rotating cylindrical part. Facing is typically done to establish the part's length.

feeds

Gradually moving the cutting tool along the workpiece surface during operation. Feed represents the linear or circular movement of the tool during cutting.

finish

To alter the texture or appearance of a part in order to obtain the desired tolerance and surface appearance. Finish can affect the way parts fit together.

finishing

A later stage in a series of operations designed to bring the part feature to its final size and produce the required surface finish. Finishing operations often require faster speeds and a lighter depth of cut.

fixture

A customized workholding device that is designed to effectively support, locate, and hold a specific workpiece design. A workpiece with multiple, complex dimensions often requires a dedicated fixture.

grooving

The process of cutting a channel or passageway on the inner or outer surface of a cylindrical workpiece. During grooving, the tool is fed into the rotating workpiece radially to a specified dimension.

holemaking

A machining operation in which a single-point or multi-point cutting tool creates, sizes, or finishes a hole. Holemaking encompasses a number of operations, including drilling, boring, reaming, and tapping.

indexes

Rotates from one fixed position to another fixed position. Lathe turrets and mill toolchangers index tools into place.

inner diameter

ID. The interior surface of a hole or cylindrical feature. Inner diameter cutting operations include drilling, boring, and tapping.

insert

A geometrically shaped component made of hardened material that is inserted into a toolholder to provide a cutting edge. The insert offers multiple cutting edges and can be indexed to present a new cutting edge after the prior edge is excessively worn.

lathe

A machine tool that is used to produce a range of cylindrical workpieces. On a basic lathe, the part is rotated in a spindle while the cutting tool is guided along its exterior diameter or into the part to create a hole located on the part's centerline.

live tooling

Rotating cutting tools held in the turret of a lathe. Live tooling allows the lathe to perform holemaking operations away from the centerline of the part as well as other operations traditionally done on a mill.

machine tool

A very general term for any powered machine that is used to manufacture parts by guiding a tool. Common examples of machine tools include the saw, the drill press, the lathe, and the mill.

machining

Manufacturing a part by using a tool to remove material in the form of chips. Milling, drilling, turning, sawing, and grinding are all types of machining operations.

metal

A naturally occurring material with high electric and thermal conductivity, luster, density, and strength. Examples of metal include copper, iron, nickel, and lead.

mill

A machine tool that is used to produce a range of rectangular or prismatic workpieces. On a basic mill, the part is clamped to a worktable while a rotating cutting tool is passed along its various surfaces to remove material or is fed into the part to create holes and other features.

milling

A cutting operation in which a rotating multi-point cutting tool is fed along a part's surface to remove material. Milling operations are very versatile and generally produce flat surfaces.

multi-point tooling

A machining tool that has two or more cutting edges. Multi-point tooling operations use such tools as mills, drills, and reamers.

outer diameter

OD. The outer surface of a cylindrical workpiece or feature. Outer diameter cutting operations include turning, cutoff, threading, and grooving.

plastic

A material consisting of very large molecules that is characterized by light weight, high corrosion resistance, a high strength-to-weight ratio, and a low melting point. Most plastics are easily shaped or formed.

pocket milling

The use of a milling cutter to create an interior recess in the surface of a workpiece. Pocket milling may create square, round, or rectangular pockets.

profiling

A machining operation performed on a lathe that feeds a cutting tool along a non-linear path. Profiling creates complex or curved features in a cylindrical workpiece.

ratio

The relationship between two quantities sometimes expressed as a fraction. On the lathe, ratio is an expression of taper in inches per foot, such as 1:12.

raw material

An unprocessed material that has not yet been manufactured. All workpieces begin as raw material.

reamer

A multi-point cutting tool with straight cutting edges that is used to enlarge or smooth holes that have been previously drilled. Reamers look similar to a drill but lack a cutting point.

reaming

The use of a cutting tool with straight cutting edges to enlarge or smooth holes that have been previously drilled. Reaming can tighten the tolerance of a machined hole.

reciprocates

To move back and forth repeatedly. Some sawing operations involve a reciprocating motion.

rotary tables

A worktable on a mill that provides an additional rotational axis for positioning the workpiece. Rotary tables are helpful in machining complex parts.

roughing

A cutting pass that emphasizes high material removal rates at the possible sacrifice of surface finish or accuracy. Roughing cuts are often the first cuts made in a machining operation.

sawing

A basic metal cutting process that uses a blade with a series of teeth on its edge to cut a narrow opening in a workpiece. Sawing may be used to produce slots or grooves or to separate a workpiece into two pieces.

single-point tooling

A machining tool that has a single cutting edge. Turning and boring are performed with single-point tooling.

slot milling

A milling operation that produces a narrow channel or groove in the workpiece. During slot milling, an end mill engages the workpiece on its bottom and sides.

spindle

The part of the machine tool that spins or rotates. On the mill, the spindle holds a cutting tool, while on the lathe, the spindle holds the workpiece.

spot drilling

The use of a shorter, sturdier drill to locate a hole for drilling. Spot drilling often uses a drill size slightly larger than the hole diameter to leave a chamfer after the hole is drilled.

surface finish

The degree of smoothness of a part's surface after it has been manufactured. Surface finish is the result of the surface roughness, waviness, and flaws remaining on the part.

table

The part of the machine that supports the workpiece and any workholding devices. Tables often move to change the position of the workpiece relative to the cutting tool.

tailstock

The component located at the end of a lathe opposite the headstock. Tailstocks support the end of longer workpieces.

tapering

Cutting a workpiece to form a shape with a gradually decreasing diameter, similar to the shape of a cone. Tapering can be performed on a lathe.

tapping

The process of cutting internal threads in a round hole with a multi-point tool. Tapping can be performed on a drill press or lathe.

thread

A long, spiraling groove that is machined into a workpiece. Threads are essential for the creation of fasteners.

threading

The process of cutting a long, spiraling groove into a workpiece with a single-point tool. Threading processes are essential for the creation of fasteners.

tolerances

An unwanted but acceptable deviation from a given dimension. Tolerances indicate the allowable difference between a physical feature and its intended design.

toolchanger

A device on a machining center that arranges multiple cutting tools in order and then positions these cutting tools for replacement. Toolchangers allow many cutting tools to be used in a single operation.

toolpath

The course followed by the tool as it creates the workpiece. Toolpaths are often described by a series of coordinate positions.

turning

A machining operation that rotates a cylindrical workpiece while a single-point tool is guided along the length of the part. Turning is performed on a lathe.

turret

The component of a lathe that holds a number of cutting tools. The turret rotates to place tools in the cutting position.

vise

A workholding device with two jaws that grip and hold a workpiece in place. Vises are often used to hold workpieces on a mill or machining center.

walking

The unintended movement or repositioning of a cutting tool or component due to a mechanical force. Walking, or deflection, of a cutting tool can cause poor surface finish and inaccurate dimensions.

ways

Two precisely measured, parallel tracks that support and guide the movement of a machine tool component. Lathe ways guide cutting tool movements, while mill ways guide the position of the mill table.

workpiece

A material that is being machined or undergoing another type of processing. Workpieces can be shaped by processes such as cutting, welding, and grinding.