Vocabulary and Glossary

Manufacturing and Machining Vocabulary

eMachineShop defined vocabulary.

Threading Glossary

eMachineShop defined threading glossary.

Manufacturing and Machining Vocabulary

2D (Two-Dimensional)

A part is considered 2D if the Z-value of all internal features are set to “Air-Inside,” doesn’t contain edge effects, and only the top view is used. 2D parts with bends are also considered 2D.

3D (Three-Dimensional)

A part is considered 3D if it contains multiple Z-values, edge effects are selected or more than just the top view is used.


The direction along which the relative movements of a tool or workpiece occur. The three linear axes, occurring 90° angles relative to each other, are named X, Y and Z.

CAD (Computer Aided Design)

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 the machines that fabricate parts.

Coefficient of Friction

The ratio of the friction force to normal force.


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


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


Mechanical resistance of motion between two surfaces.


The industry standard programming language that controls a CNC machine.


The wear that occurs due to 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 process of controlling a machine or process by programming command instructions using code.


The process of moving a line a fixed distance using the arrow keys.


The nominal distance between centers of repetitive shapes.


A line having more than one segment.


The measurement that represents how smooth a surface is 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.


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


The process of moving a line so it meets a key point on another line.

Static friction

The friction between two surfaces with no relative motion. It is the force required to start relative movement AKA stiction.


The point on a curve that is parallel to a straight line.


The path a cutting tool travels to remove material and create shapes.


The measurement of twisting force applied to a fastener, shaft or other rotating member. It is often measured in newton-metres (Nm) or foot-pounds (ft-lb).


The acceptable variation in specified dimensions.

Z Axis

The third dimension that cannot directly be shown in a flat drawing. The distance perpendicular to the screen.

Threading Glossary

Angle of Thread

The angle between flanks.

External Thread

A thread formed on the external surface of a cylinder.


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 thread roots or crests next to each other; or between the centers of other repetitive shapes.

Right-Hand Thread

The most common type of thread. It is a screw thread that is tightened by rotating clockwise when viewed from the head.

Rolled Thread

A thread formed by plastic deformation of a rod instead of cutting.

Shoulder Screw

A screw with an unthreaded portion used for more precise and secure locating. It can also be used as a bearing surface like in pulleys.

UNC/UNRC (Unified National Coarse)

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)

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, or when instruments and parts require fine adjustments.

UNEF/UNREF (Unified National Extra-Fine)

A thread form using a finer pitch than UNF. It is used for the same reasons that UNF is used over UNC, but for more strict requirements.