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Machining & Manufacturing Vocabulary

Read our manufacturing glossary for definitions of terms used in the manufacturing, engineering, and CAD software fields:

2D (Two-Dimensional)A part design where the Z value of all internal holes and cutouts are air-inside and no edge effects (rounded edges, chamfered edges, sloped walls, or side grooves) are selected and only one view is used (the Top view). 2D parts with bends are still considered 2D.

3D (Three-Dimensional)  A part design where Z values vary or edge effects (rounded edges, chamfered edges, sloped walls, or side grooves) are selected or more than one view is used.

Axis – A principal direction along which the relative movements of a tool or workpiece occur. Three linear axes, occurring at 90° angles from each other, named X, Y and Z.

CAD – (Computer Aided Design) The use of computer applications that allow you to design mechanical parts and other items.

CAM – (Computer Aided Manufacturing) The use of computers to assist in manufacturing.

CNC – (Computerized Numerical Control) The computer control of machines that fabricate custom parts.

Coefficient of friction – The ratio of the friction force to normal force. For example, if it takes 1 lb of force to slide a 10 lb weight along a level surface the coefficient of friction is 0.1. The coefficient depends on the two materials involved.

Creep – The deformation of a part over time when under constant stress.

Fillet – In mechanical engineering, a fillet is a rounding of an interior or exterior corner of a part design.

Friction – Mechanical resistance of motion between two surfaces.

G-Code – The industry standard programming language that controls a CNC machine.

Galling – A type of wear that occurs because of adhesion between sliding surfaces.

Machining Center – Machine tools that are capable of automatically repeating operations such as drilling, reaming, tapping, milling, and boring multiple faces on a workpiece.

Machine Tool – A power-driven machine used to form or shape metal and other materials.

N/C Numerical Control – The technique of controlling a machine or process by using programmed command instructions provided by coding.

Nudge – The process of moving a line a fixed small distance across the screen using the arrow keys on the keyboard.

Pitch – The nominal distance between centers of repetitive shapes.

Polyline – A line having several segments. For example, a rectangle is a polyline with four segments.

Roughness – A measurable degree of non-smoothness of the surface related to the height of the peaks and valleys.

Set Screw – A threaded fastener typically used to lock a sleeve, collar or gear on a shaft. Set screws are normally headless. Set screw points can have various shapes including cups, cones, ovals, flats and more.

Shank – The section of a bolt between the head and the threads. Sometimes refers to the section of a cutting tool that is held.

Snap – The process of moving one line so it exactly meets a key point on another line.

Static friction – The friction between two surfaces having no relative motion. It is the force required to start relative movement. Also known as stiction.  

Tangent – Two curves or lines that are parallel at the point where they meet.

Toolpath – The path that a cutting tool travels to remove material to create a shape.

Torque – A measure of twisting force applied to a fastener, shaft or other rotating member. Force is often measured in newton-metres (Nm) or foot-pounds (ft-lb).

Tolerance – The acceptable variation in measurement.

Z Axis – The third dimension that cannot directly be shown in a flat drawing. The distance out from the drawing towards yourself.

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Threading Glossary

Angle of Thread – The angle between the flanks.

External Thread – A thread formed on the external surface of a cylinder (e.g. a screw).

Flank – The flanks of a thread are the straight sides that connect the crest and the root.  

Major Diameter – The diameter of an imaginary cylinder that just touches the crests of an external thread or roots of an internal thread.

Minor Diameter – The diameter of an imaginary cylinder that just touches the roots of an external thread or crests of an internal thread. Also called Root Diameter.

Pitch (threading) – The nominal distance between two adjacent thread roots or crests; or between the centers of other repetitive shapes.

Right-Hand Thread – A screw thread that is tightened by rotating clockwise when viewed from the head. Most screws are right handed.

Rolled Thread – A thread formed by plastic deformation of a rod instead of cutting. Most fasteners are formed this way.

Shoulder Screw – A screw with an unthreaded portion used for more precise and secure locating or as a bearing surface such as in a pulley.

UNC/UNRC – Unified National Coarse is a thread form with a 60 degree flank angle, rounded roots and flat crests. The unified thread is based on inch sizes and was first standardised in 1948. It is the most commonly used thread system used in the majority of screws, bolts, and nuts.

UNF/UNRF – Unified National Fine is a thread form using a finer pitch than UNC. It is used when a higher tensile strength is needed than the coarse thread series; when smaller length of engagement is needed; when a thinner wall is available; and when instruments and parts require fine adjustments.

UNEF/UNREF – Unified National Extra-Fine is a thread form using a finer pitch than UNF. It is used for the same reasons that UNF is used over UNC but for even more stringent requirements.


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