Appx E - Glossary

• 1-2-3 Block - A precision ground block that is 1x2x3 inches. Useful for helping set up the machine.

• 2D - A prismatic part of constant thickness.

• 2-½ D - A prismatic part with multiple thicknesses. All planes are parallel to each other.

• 3D - A part that is not completely prismatic, including molds and organically shaped parts.

• Burr - A sharp edge or flashing.

• Block - A line of code in a CNC program.

• CAD - Computer Aided Design

• CAM - Computer Aided Manufacturing.

• CDC - Cutter Diameter Compensation.

• CNC - Computer Numerical Control.

• Chip Load - The amount of material removed with each pass of a tool cutting edge.

• Datum - Point on the part from which all coordinates are referenced.

• Drill Chart - A table that shows drill sizes, their decimal equivalent, and what size drill to use for a specified tap.

• Feed - The linear speed at which a tool advances through material.

• First Article - The first part machined with a new program and setup.

• G-M Code - The CNC machine tool language.

• Gouge - An error that causes an overcut on the part.

• High Speed Machining (HSM) - Toolpath strategies that minimize machining time and tool breaking. Includes several technologies such as Adaptive Roughing that maintain a constant amount of tool engagement.

• Home - Location of machine after it is turned on and moved to its start position.

• ID - Inside diameter or contour, like a pocket.

• Insert - Carbide composite cutting tool used extensively for turning operations.

• Job - A sequential list of one or more machining operations that share the same setup and fixture offset.

• Machine Coordinate System - Coordinates in reference to the machine Home position.

• Mill - A machine tool that removes material by spinning a tool and moving it in relation to the part.

• OD - Outside diameter or contour.

• Overcut - Describes a machined feature is too big because not enough material was removed during machining.

• Post Processor - The part of a CAD/CAM system that actually creates and formats the CNC program for a specific machine and control.

• Rapid - The fastest linear feed rate at which a machine tool can move.

• Reference Point - Some point on the part that can be found reliably by mechanical means.

• Rigid Tapping - The capability of a CNC machine to control a tap without the use of a special tapping attachment.

• Scallop - Ridges left on the part, usually from a ball or bull nose end mill on a 3D sculpted surface.

• Setup- A complete set of work holding to machine one side of a part.

• Speed - How fast a tool turns in RPM.

• Spindle - Part of CNC machine that grips and spins the cutting tool.

• Stepdown - Distance the tool moves down in Z between machining passes.

• Stepover - Distance the tool moves over in the XY plane between machining passes.

• Stock Allowance - Amount of material left after a machining operation or pass to be removed by a finish pass.

• Spring Pass - Two or more machining passes that follows the exact same path. Used to straighten walls and improve surface finish.

• TLO - Tool Length Offset. Used to tell CNC machine the length of a tool.

• Tool Changer - A device on a CNC machine that automatically takes tools from a carousel and places them in the machine spindle.

• T-Slot - A slot in the machine table into which a special T-nut can be inserted. Used to fasten clamps or parts to the machine table.

• Turret - Lathe assembly that attaches the lathe tool holder to the machine.

• Undercut - Describes a machined feature is too small because too much material was removed during machining.