Basics of the CNC Lathe 211

axis

An imaginary straight line or circle used to describe the location or movement of an object in three-dimensional space. Horizontal lathes spin along a horizontal axis of rotation.

ballscrew

A long, threaded device that rotates to move the worktable or cutting tool of a CNC machine. Ballscrews are powered by a servomotor.

bar machine

A lathe that continuously cuts a number of parts from a piece of bar stock. Bar machines use collets to hold the bar stock during cutting operations.

bar stock

Raw material sold in the form of long bars. Bar stock can be round, square, or hexagonal.

bed

The main supporting structure upon which the operating parts of the machine are mounted and guided. Both the headstock and tailstock rest upon the bed of the lathe.

boring

The process of enlarging or smoothing an existing hole with a single-point tool. Boring is an inner diameter operation.

boring bar

A long bar used to position a single-point tool for boring operations. Boring bars are usually a round shank.

carbide

A compound developed by the combination of carbon with other elements such as chromium, tungsten, or titanium. Carbide is often used to make metal cutting tools.

carbide insert

A replaceable cutting bit made out of carbide that has multiple cutting edges. Carbide inserts can be indexed to another cutting edge once one is excessively worn.

carriage

The section of the lathe that slides back and forth along the ways. Carriages support the cross slide and turret.

castings

A workpiece formed by melting various raw materials, pouring them into a mold or cavity, and removing the workpiece once the materials have cooled and solidified. Metal castings are machined in a chucker.

center

The device in a lathe or turning center that supports the end of a cylindrical workpiece opposite the spindle. Centers are located in the tailstock.

chamfering

A lathe cutting operation that creates an angled edge around the end of a cylindrical workpiece or the entrance of a hole. Chamfering can be an inner or outer diameter operation.

chuck

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

chuck

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

chucker

A lathe that requires an operator to load one workpiece at a time. The workholding device used for a chucker is called a chuck.

CNC lathe

A machine that uses computerized numerical data to control workpiece rotation and cutting tool movements for the machining of cylindrical parts. CNC lathes are precise and versatile.

collet

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

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 bar diameter and shape dimensions.

computer numerical control

CNC. A self-contained system of computers and precision motors that executes program instructions to guide machine tool components and manufacture parts. CNC machines can be either open-loop or closed-loop systems.

contour turning

A lathe cutting operation that creates curved or complex shapes on the workpiece surface. Contour turning is an outer diameter operation.

cross slide

The toolholding component of a lathe that allows tools to approach a workpiece centerline. Cross slides are supported by the carriage and positions the turret toward and away from the workpiece.

cutoff

A slicing operation performed on a lathe that uses a cutting tool to separate a finished part from the rest of the stock. A cutoff operation is an outer diameter operation.

cutoff tool

A cutting tool that separates a part from the rest of the stock. Cutoff tools establish the final length of a part.

depth of cut

The distance that a cutting tool penetrates the surface of a workpiece. Depth of cut determines the amount of material removed with each cutting pass.

depth of cut

The distance that a cutting tool penetrates the surface of a workpiece. Depth of cut is determined by the cross slide on a lathe.

drilling

The use of a multi-point tool to machine a new round hole into the surface of a workpiece. Drilling is one inner diameter operation that a CNC lathe can perform.

drills

A metal cutting tool used to penetrate the surface of a workpiece and make a round hole equal to the drill diameter. Drills on CNC turning centers are powered by a small motor in the turret.

facing

A lathe cutting operation that feeds a cutting tool across an end of a cylindrical workpiece to create a flat surface and shorten its length. Facing is an outer diameter operation.

feature

A defining characteristic. Features include shapes, lines, and other elements machined into a workpiece.

feed

The rate at which the cutting tool moves down the length of the workpiece on a lathe. Feed is typically a linear movement.

forgings

A workpiece formed by compressing or hammering hot metal to achieve a specific shape. Forgings are machined in a chucker.

grooving

A lathe cutting operation that cuts a narrow channel into a rotating cylindrical workpiece. Grooving can be an inner or outer diameter operation.

headstock

The end of a lathe that holds the spindle and the spindle drive that rotates the workpiece. Headstocks hold the workpiece in place on the spindle-end of the lathe.

high-speed steel

HSS. A category of tool steels used for cutting tool applications. Drills and other multi-point tools are often made of high-speed steel.

hydraulics

A system that uses the force of flowing liquids to transmit power. Hydraulics can be used to power a chuck.

inches per minute

ipm. A unit of measurement that indicates how far in inches a tool advances in one minute. Inches per minute is used to measure feed.

inches per revolution

ipr. A unit of measurement that indicates how far in inches a tool advances in one rotation. Inches per revolution is used to measure feed.

index

To rotate a cutting head from one fixed position to another fixed position in order to reveal a fresh cutting edge. A cutting tool with multiple cutting edges should be indexed once the original edge has been worn or damaged.

inner diameter

The interior surface of a workpiece. Inner diameter cutting operations include drilling, reaming, and boring.

lathe

A machine tool used to create cylindrical parts. Lathes hold a cylindrical workpiece on one or both ends while moving a single-point cutting tool along the surface of the rotating part.

live tooling

A feature that equips the turret with power-driven tools such as end mills and drills. Live tooling can perform cutting operations off-center while the workpiece is held still in the spindle.

meters per minute

m/min. The distance, in meters, that the cutting surface and workpiece move past one another at the point of contact in one minute. Meters per minute is also sometimes required to as surface meters per minute, or smm.

millimeters per minute

mm/min. A unit of measurement that indicates how far in millimeters a tool advances in one minute. Millimeters per minute is used to measure feed.

millimeters per revolution

mm/rev. A unit of measurement that indicates how far in millimeters a tool advances in one rotation. Millimeters per revolution is used to measure feed.

mills

A multi-point cutting tool that has teeth around its cutting surface. Mills are often used to create flat or contoured surfaces.

outer diameter

OD. The external surface of a workpiece. Outer diameter cutting operations on the lathe include turning, facing, and cutoff.

parts catcher

A device used to catch a part once it is separated from the stock. A parts catcher is one component in a bar machine.

pneumatics

A system that uses the force of flowing gases to transmit power. Pneumatics can be used to power a chuck.

radial

A direction that radiates outward from a common center. The cross slide determines the radial depth of cut on a CNC lathe.

reamer

A multi-point cutting tool with straight cutting edges used to enlarge or smooth holes that have been previously drilled. On a lathe, reamers are held in place by a collet.

reaming

The process of enlarging or smoothing an existing hole with a multi-point tool. Reaming is an inner diameter operation.

revolutions per minute

rpm. The number of revolutions that a spindle or cutting tool completes in one minute. Revolutions per minute is a measurement of speed in both English and metric systems.

rotational speed

The rate at which the spindle rotates. Rotational speed indicates how fast the workpiece is spinning.

servomotor

A motor in a CNC machine that powers movement of the machine tool. Servomotors rotate the ballscrew on a CNC machine, causing the table of a mill or the slides of a lathe to move.

spindle

The part of the machine tool that rotates. On the lathe, the spindle holds the workpiece.

spindle drive

The main device that powers the rotation of the lathe spindle. Drives are located in the headstock.

stock

Raw material that is used to make manufactured parts. Stock is available in standard shapes, such as long bars, plates, or sheets.

stock stand

The component of a bar machine that supports the bar stock. Stock stands feed bar stock through the machine one workpiece length at a time.

surface feet per minute

sfm. The distance, in feet, that the cutting surface and workpiece move past one another at the point of contact in one minute. Surface feet per minute depends on depends on cutting diameter or cutting tool size and RPM.

tailstock

The part of a lathe located opposite the headstock. Tailstocks can hold a center to support longer workpieces or an internal diameter cutting tool.

taper turning

A lathe cutting operation that gradually increases or decreases the diameter along the workpiece length to create a conical shape. Taper turning is an outer diameter operation.

taps

A multi-point cutting tool used to create internal threads. On a CNC lathe, taps are held by the turret.

threading

The process of cutting a long, spiraling groove into a cylindrical workpiece with a single-point tool. Threading can be an inner or outer diameter operation.

threads

A long, spiral ridge around the exterior or interior of a cylindrically shaped object. Threads are used to fasten or provide motion.

tolerances

The unwanted but acceptable deviation from a desired dimension. To meet specifications, a workpiece must stay within its tolerances.

toolholder

A device used to rigidly hold a cutting insert in place during machining. Toolholders generally hold an indexable insert.

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.

turning center

A sophisticated CNC lathe that can perform a variety of drilling and milling operations all at the same location. Turning centers usually use live tooling.

turret

A lathe component that holds a number of cutting tools. Turrets rotate or index to place tools in cutting position.

vertical lathe

A lathe with a spindle axis that is perpendicular to the ground. Veritcal lathes are ideal for turning excessively large and heavy workpieces.

ways

Two precisely measured, parallel tracks that support and guide the movement of the carriage and cross slide of the lathe. Ways are located along the bed of the lathe.

workholding

The process of securely supporting, locating, and clamping a workpiece for a manufacturing operation. Chucks and collets are both workholding devices.

workpiece

A part that is in the process of being manufactured. A workpiece may be a complete product in itself or one component of a product consisting of many parts.