Machining Terminlogy Explained

Term	Definition
American-type single-spindle screw machine	A modified automated lathe distinguished by a turret that approaches a work piece from the axial orientation.
automatic bar machine	A turning machine that continuously cuts a number of parts from a piece of bar stock,one after another. The bar stock advances through thespindle and is held by the collet during the operation. A bar machine is traditionally called a screw machine.
axial approach	A tool approach that runs parallel to the axis of a work piece. Also called the parallel orientation.
bar stock	Raw material purchased from metal manufacturers in the form of long bars. Bar stock may be round, square, or hexagonal.
bar stock magazine	A chamber that allows the feeding of bar stock, one at a time, into a machine.
boring	The process of using a single-point tool to enlarge a pre-existing hole.
bushing	A guide for bar stock on the Swiss-type single-spindle screw machine that enables the creation of very small parts with excellent tolerances.
cam	A circular or cylindrical machine component that converts rotational movement into linear movement. A cam controls the feed rate and depth of cut of cutting tools on the automatic bar machine.
chip	An unwanted piece of metal that is removed from a work piece. Chips are formed when a tool cuts or grinds metal.
chuck	A device that holds a work piece in place as it rotates. The chuck commonly has three or four jaws that can be adjusted to fit various sizes of parts.
chucking machine	A general name for any lathe that uses a chuck to hold the part. An operator must load and unload each individual work piece.
CNC turning center	A sophisticated CNC machine that specializes in turning, boring, drilling, and threading operations, all at the same location.
collet	A slitted device that holds a work piece in place as it rotates. A collet has a hole through which the work piece passes, and it is designed to hold specific dimensions. Collets can also be used to hold cutting tools.
computer numerical control	A sophisticated machine tool that uses a computer and special programs to carry out various machining operations. The turning center is an example of a lathe equipped with computer numerical control (CNC).
cross slide	On a lathe, the tool-holding components that allow tools to approach a work piece from a perpendicular, or radial, orientation.
cutoff	An operation performed on the lathe that uses a cutting tool to separate a finished part from the rest of the stock.
cycle time	The time it takes to make one part.
depth of cut	The amount of material that is removed with one pass of a cutting tool.
drilling	The process of using a multi-point tool to penetrate the surface of a work piece and make a round hole.
drive shaft	Located in the base of a turning machine, the device that transfers power from the motor to all machine components.
engine lathe	The original and most basic type of lathe.
facing	An operation performed on a lathe that feeds a single-point tool across the end of a cylindrical work piece to create a flat surface.
feed	The linear movement of a cutting tool into a part to remove material.
follower	A machine component that traces the outline of a cam and thus controls the way a work piece is cut.
form turning	An operation performed on a lathe that feeds a tool into a work piece in order to impart the tool's shape in the work piece.
headstock	The end of a lathe that holds the spindle and the drive that rotates the work piece.
horizontal axis	An imaginary line that passes through the center of an object and is parallel to the floor.
ID grooving	The process of cutting an internal channel or passageway into a drilled hole.
index	The changing of machine components to a different position.
inner-diameter operation	A cutting operation that takes place on the interior surface of a cylindrical work piece.
lathe	A machine tool commonly used to create cylindrical parts. A lathe holds a cylindrical work piece on one or both ends. The cutting tool is gradually passed along the surface of the rotating part.
machine motor	The primary source of power that is located in the base of a lathe.
mechanical safety clutch	A safety device that disengages the drive shaft from the motor.
multiple-spindle screw machine	An automatic bar machine that contains more than one spindle, usually 4, 6, or 8. Multiple spindles allow multiple tools to cut multiple work pieces simultaneously.
OD chamfering	An operation performed on a lathe that feeds a tool to create an angled edge on the work piece.
OD threading	An operation performed on a lathe that cuts a long, spiraling ridge down the outer surface of a work piece.
outer-diameter operation	A cutting operation that takes place on the outer surface of a cylindrical work piece.
radial approach	A tool approach that runs perpendicular to the axis of a work piece. Also called the perpendicular orientation.
reaming	The process of using a multi-point tool to smooth the interior surface of a hole.
screw machine	An automated turning machine that continuously creates a number of finished parts from bar stock. Bar stock advance through the spindle and is held by a collet. It is also commonly called a bar machine.
setup	Time that is spent setting up the fixtures and tooling, calculating tool offsets, and performing all the necessary tasks to produce the first accurate part.
single-point cutting tool	A cutting tool that uses a single cutting edge to remove material.
single-spindle screw machine	An automatic bar machine that contains one spindle. The spindle rotates one piece of bar stock, which is cut by one tool at any given time.
spindle	The part of the machine tool that spins. On a screw machine, the spindle holds the work piece.
Swiss-type single-spindle screw machine	A modified automated turret lathe distinguished by a sliding headstock and fixed bushing. Swiss-type machines are capable of creating very small parts with excellent tolerances.
tailstock	A device located at the end of a lathe opposite the headstock that supports the end of longer work pieces.
taper turning	An operation performed on a lathe that feeds a tool at an angle to the length of the work piece in order to create a conical shape.
tapping	The process of cutting internal threads in a work piece with a multi-point tool.
tolerance	An unwanted but acceptable deviation from a given dimension. Tolerances indicate the allowable difference between a physical feature and its intended design.
turning	A machining operation used to make cylindrical parts. A single-point cutting tool passes along the outer surface of a cylindrical work piece as it rotates and gradually removes a layer of material.
turret	The component of a lathe 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 rotates to position one specific cutting tool in place after another.
vertical turning machine	A turning machine in which the spindle is perpendicular to the ground floor. Vertical turning machines are often used for very large or heavy parts.
work holder	A device used to locate and hold a work piece in place.