Overview of Machine Tools 121

arbor

An axle-like machine component attached at one end to the spindle in a horizontal milling machine. The arbor holds and rotates the milling cutter.

automatic bar machines

A turning machine that continuously cuts a number of parts from a piece of bar stock. Automatic bar machines are also known as bar feeding machines.

axis

An imaginary straight line that passes through the center of an object. A cylindrical workpiece typically rotates around its axis.

band saws

A saw that uses a saw blade constructed from a continuous loop or band of metal. Band saw blades are flexible, so they are able to cut gradually curving lines in flat workpieces.

bar feeding machines

A turning machine that continuously cuts a number of parts from a piece of bar stock. Bar feeding machines are also known as automatic bar machines.

bar stock

Raw material purchased from metal manufacturers in the form of long pieces. Bar stock is a common form of workpiece material.

base

The foundation of a machine that supports all the other machine components. Bases provide both stability and rigidity.

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.

bed-type milling machine

A type of milling machine with a large bed that only moves along a horizontal axis. Bed-type milling machines mill large, flat workpieces.

boring

The process of enlarging an existing hole with a single-point tool. Boring is commonly performed on a lathe.

broach

A multi-point cutting tool made of a series of teeth that progressively increase in size. Broaches can both remove metal and finish the surface of a workpiece with one pass of the cutting tool.

broaching machine

A machine that uses a multi-point cutting tool to shape and finish either the interior of a hole or the surface of a workpiece. Broaching machines remove large amounts of material from a workpiece.

carbide insert

A cutting tool made of hard material that has multiple cutting edges. Once a carbide insert's cutting edge is excessively worn, it can be indexed to another edge, or the insert can be replaced.

carriage

The section of the lathe that supports the cutting tool. The carriage slides back and forth along the ways.

center

A device located in the tailstock of a lathe or turning center. Centers support the end of a cylindrical workpiece opposite the spindle.

chips

An unwanted piece of metal that is removed from a workpiece during cutting or grinding. Chips resemble curls, shards, fragments, or particles of metal.

chucks

A device that holds a workpiece in place as it rotates on a lathe or other machine. The chuck commonly has three or four jaws that can be adjusted to fit various workpieces.

circular saws

A saw that cuts with a toothed or abrasive disk. Circular saw blades rotate at high speed.

collets

A slitted device that holds a workpiece or cutting tool in place as it rotates. A collet has a hole through which the workpiece or tool passes, and it is designed to hold specific dimensions.

column

The vertical support, or backbone, of a machine. The column is a large four-, six-, or eight-sided device that accommodates the mounting of fixtures on milling machines.

column-and-knee milling machine

A milling machine with a spindle that is mounted in the column and a worktable that rests on an adjustable knee. Column-and-knee milling machines are manual machines.

compound rest

The part of the lathe that allows for angular adjustment of the cutting tool. The compound rest holds the toolpost and is located on the carriage.

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.

contours

A curved, non-linear dimension created by a cutting process. Contours can be created by precise tool movements in milling.

countersinking

The cutting of a beveled edge at the end of a hole. Countersinking allows the head of a screw to rest level with the workpiece surface.

cutting

The use of single- or multi-point tools to separate metal from a workpiece in the form of chips. Cutting processes vary based on the requirements of a finished part.

cutting tool

A device with one or more edges that is designed to cut metal. Cutting tools are often designed to be used on a machine such as a mill or lathe.

drill bit

A multi-point cutting tool used to machine round holes into workpieces. Drill bits have spiral cutting edges and are usually mounted in drill presses.

drill press

A machine tool that is used for a variety of holemaking operations. Drill presses use rotating multi-point cutting tools.

drilling

The process of using a multi-point tool to penetrate the surface of a workpiece and make a round hole. In drilling operations, the drill may rotate to cut a stationary workpiece, or a stationary drill may be fed into a rotating workpiece.

drive

The main device that powers the rotation of the spindle. The drive is located in the headstock of a lathe.

end mill

A tall, thin mill cutter with cutting edges that spiral up the sides, resembling a drill. Both the end mill's bottom and side are used during milling operations.

engine lathe

The original and most basic type of lathe. Engine lathes are often used to make cylindrical workpieces.

face mill

A flat mill cutter with multiple cutting teeth surrounding the bottom edge. The face mill is often used to remove large amounts of material to create flat surfaces.

feed handle

A handle attached to a machine. Feed handles control the movement of the cutting tool.

finishing teeth

The section of teeth on a broach that make the final finishing cuts on a surface. Finishing teeth are the largest sized teeth on the broach.

finishing tool

A cutting tool used to make a final cut. Finishing tools make final touches to achieve precise tolerances or improved finishes.

form mill

A custom-designed, uniquely shaped, type of milling cutter. Form mills are often used to mill a specific part.

friction saw

A type saw that uses high speed to generate heat to soften the metal in front of the blade. Friction saws can be used in band sawing or circular sawing.

hacksaws

A saw with a linear, toothed blade that is used in a reciprocating motion. Hacksaws only cut in one direction.

hardness

The ability of a material to resist penetration and scratching. Hardness is one of the key properties of cutting tool materials.

head

The part of a vertical column-and-knee mill that contains the spindle and the motor. The head of a vertical mill is located at the top of the column and extends over the worktable.

headstock

One of the two main ends of a lathe. The headstock holds the spindle and the drive that rotates the workpiece.

high-speed steel

HSS. An inexpensive cutting tool material that has high toughness. High-speed steel is tougher than carbide but offers less hardness and wear resistance.

HSS

High-speed steel. An inexpensive cutting tool material that has high toughness. HSS is tougher than carbide but offers less hardness and wear resistance.

indexable

Having multiple cutting edges. An indexable cutting tool can be rotated to a different cutting edge once the original edge has been worn or damaged.

internal broach

A category of broaches that remove material from internal surfaces. Internal broaches remove material as it is pulled or pushed through a workpiece hole.

keyway

A rectangular slot or groove that is machined down the length of a hole. Keyways are sometimes created by internal broaches.

knee

The device that supports and moves the saddle and worktable of a manual milling machine. Knees are supported by an elevating screw that guides the back and forth motion and raises and lowers the mill saddle.

lathe

A machine tool that holds and supports a cylindrical workpiece at one or both ends and rotates it while a single-point cutting tool removes material. Lathes are commonly used to perform turning operations.

leadscrew

The long, threaded device that times and controls the precise movement of the carriage on a lathe. The leadscrew coordinates carriage and workpiece movements.

machine tool

A power-driven machine that uses a cutting tool to remove metal from a workpiece. Machine tools can hold a variety of cutting tools.

machining

The process of removing metal to form, shape, or finish a part. Machining processes include turning, drilling, and milling.

machining centers

A sophisticated CNC machine that can perform multiple machining operations in the same setup with a variety of tools. Machining centers primarily perform milling and holemaking operations.

mill

A machine that uses a rotating multi-point tool to remove metal from the surface of a workpiece. Mills may be manually or CNC operated.

milling cutter

A rotary cutting tool with teeth around its cutting surface that is used on milling machines. Milling cutters vary greatly in size, shape, and material.

milling machines

A machine that uses a rotating multi-point tool to remove metal from the surface of a workpiece. Milling machines may be manual or CNC operated.

mills

A multi-point cutting tool that is used to remove metal from the surface of a workpiece. Mills can be made of solid metal or may hold indexable inserts.

multiple spindle drills

A drilling machine that contains two or more spindles. Multiple spindle drills perform several cutting operations at the same time.

multi-point tools

A cutting tool that uses two or more cutting edges to remove material. Multi-point tools are used in milling, sawing, and drilling.

overarm

The device on a horizontal milling machine that reaches over the workpiece and supports the arbor. The overarm extends over the machine table and workpiece.

plain mill

A wide mill cutter with cutting surfaces covering the outside edge. Plain mills, which are also called slab mills, are generally mounted on an arbor and used to mill flat surfaces.

planer-type milling machine

A very large type of milling machine that often contains numerous milling heads. Planer-type milling machines are designed to machine very large workpieces.

plate fixtures

A device used to hold workpieces parallel or perpendicular to a machine table. Plate fixtures are used in milling and other cutting operations.

plate stock

Raw material that is purchased from metal manufacturers in large, flat pieces. Plate stock is a common form of workpiece material.

pockets

An interior recess that is cut into the surface of a workpiece. Pockets can be created through milling processes.

radial drill

A drilling machine that maneuvers an overarm in place over the workpiece. Radial drills can accommodate large workpieces.

reaming

The use of a multi-point cutting tool to smooth or enlarge a previously drilled hole. Reaming tools have straight cutting edges.

reciprocating

Moving in a back-and-forth motion. In the reciprocating motion of a hacksaw, only one motion actually contacts and cuts the workpiece.

rough cutting

The quick removal of metal from a workpiece without regard to tolerances or finish. Rough cutting is generally followed with additional cutting processes.

roughing teeth

The section of teeth on a broach that makes the initial cuts in a workpiece. Roughing teeth are smaller than the other broach teeth types.

roughing tool

A cutting tool used to make very heavy cuts and remove metal as quickly as possible. Roughing tools can include broaches.

saddle

The mill component supported by the knee and located below the worktable. The saddle slides back and forth on the knee and guides the forward and back motion of the worktable.

saw

A multi-point cutting device that is used to rough cut a part to a certain length or shape. Saws come in many forms, such as band saws, circular saws, and hacksaws.

saws

A multi-point cutting device that is used to rough cut a part to a certain length or shape. Saws come in many forms such as band saws, circular saws, and hacksaws.

semi-finishing teeth

The section of teeth on a broach that follows the roughing teeth and precedes the finishing teeth. Semi-finishing teeth make lighter cuts than roughing teeth but heaver cuts than finishing teeth.

setup

All of the tasks and preparations necessary to prepare for a machining operation. Setup can include preparing machines as well as collecting paperwork, tools, and materials.

shell mill

A type of milling cutter that has cutting surfaces around its outside edge and can be mounted on an arbor. Shell mills are designed to machine large surfaces.

side mill

A narrow, disk-like milling cutter that has cutting edges on its outside edge. Side mills are also known as slotting cutters.

single-point tools

A cutting tool that uses a single cutting edge to remove material. Single-point tools are often used by lathes.

slab broach

A flat-shaped broach that removes metal from the workpiece surface. Slab broaches are often used to form a workpiece's outside surface.

slab mills

A wide mill cutter with cutting surfaces covering the outside edge. Slab mills, which are also called plain mills, are generally mounted on an arbor and used to mill flat surfaces.

slotting cutter

A narrow, disk-like milling cutter that has cutting edges on its outside edge. Slotting cutters are also known as side mills.

spindle

The part of a machine that rotates. On the mill, the spindle rotates a cutting tool, but on the lathe, the spindle rotates the workpiece.

spindle

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

stock

The raw material out of which manufactured parts are made. Stock is available in different shapes such as bars and sheets.

surface broach

A category of broaches that remove material from external surfaces. Surface broaches include slab broaches.

tailstock

One of the two main ends of a lathe. The tailstock holds the center, which supports the workpiece at the opposite end from the headstock.

tapping

The process of cutting internal threads in a workpiece. Tapping uses a rotating multi-point tool.

tolerances

The unwanted but acceptable deviation from the desired dimension. Tolerances dictate the final size, shape, and surface finish of a part.

toolholder

The device used to rigidly hold a cutting tool in place. Toolholders are available in standardized sizes.

tough

Able to absorb energy without breaking or fracturing. Tough cutting tools are able to withstand a sudden stress.

T-slot cutter

A type of milling cutter that is used to machine a T-shaped slot into a workpiece. T-slot cutters often resemble a toothed disk mounted on a narrow arm.

turning

A machining operation in which a single-point cutting tool passes along the outer surface of a cylindrical workpiece. In turning operations, the tool gradually removes a layer of material as it rotates.

turning center

A sophisticated lathe machine controlled by a computer that can perform mulitiple operations. Turning centers specialize in turning, boring, drilling, and threading operations.

turret

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

turret lathe

A lathe with a mounted device that holds multiple cutting tools. The turret lathe rotates to position a specific cutting tool in place.

vises

A workholding device with one fixed and one moveable jaw. Vises are the standard workholding for milling operations.

ways

Two precisely measured, parallel tracks that support and guide the movement of the lathe's carriage. Ways on a lathe extend for the full length of the machine.

workpiece

Any part that is being machined, formed, or otherwise worked on. Workpieces are unfinished parts.

worktables

The part of a machine tool that supports the workpiece and any workholding devices. The worktable can adjust left to right.