The Ultimate CNC Machining Glossary

There’s a lot of terminology to get your head around regarding CNC machining.

Knowing your toolpath from your pitch or your spindle from your fixture is about more than just sounding knowledgeable. It’s about understanding the processes of creating precision-engineered parts and components.

That’s why we’ve put together this glossary to help you decode the language of CNC machining. We’ve broken down the jargon to make it as straightforward as possible so you can better understand the ins and outs of the machining process.

A

Automatic Tool Changer (ATC): A device found in CNC machines that improves the speed and efficiency of the machine by automatically changing out different tool bits or drill bits. This eliminates manual tool changes and allows for more complex, unattended multi-step machining operations.

Axes: In CNC machining, the term refers to the directions in which the machine can move a tool or workpiece. The standard axes are X, Y, and Z, but many machines also feature A, B, and C rotational axes. The X-axis typically represents side-to-side movement, the Y-axis represents front-to-back movement, and the Z-axis represents up-and-down movement.

B

Backlash: This is the slight movement or slack in the mechanical system of a CNC machine when the direction is changed, and no movement should occur. It’s typically considered an error, as precise movements are critical in CNC machining, and high-quality machines minimize backlash.

Ball Screw: A high-efficiency mechanical device in CNC machines that converts rotational motion into linear motion and vice versa. The ball screw consists of a screw, a nut, and ball bearings that reduce friction, increase machine efficiency and accuracy, and allow for precise movement control.

Bevel: A type of edge finish typically created by a CNC machine. A bevel is an edge that is not perpendicular to the top or bottom surfaces of the workpiece. Bevels create a specific angle that facilitates a better fit in the assembly.

C

Chamfer: A chamfer is a beveled edge connecting two surfaces on a piece of material, often created at a 45-degree angle. In CNC machining, a chamfer is used to create a sloping edge, to facilitate assembly, or to improve the final product’s aesthetic quality.

CAD (Computer-Aided Design): CAD uses software to create, modify, analyze, or optimize a design. It is often used in conjunction with CNC machining. This technology dramatically enhances the accuracy and efficiency of the design process and allows for easy changes and adaptations of designs.

CAM (Computer-Aided Manufacturing): CAM software converts CAD designs into instructions that CNC machinery can understand. These instructions are known as G-Code and are used by the CNC machine to create the physical product.

Chip Load: The chip load is the material a cutting tool removes in one cutter revolution. It’s usually measured in inches (or millimeters) per tooth. Optimizing chip load is essential for maximizing cutting efficiency and prolonging tool life.

CNC (Computer Numerical Control): This refers to the automated control of machining tools using a programmable device. In a CNC machine, pre-programmed software dictates the movement of factory tools and machinery, which can control a range of complex machinery, from grinders and lathes to mills and routers.

Coolant: In CNC machining, coolant is a liquid that reduces the heat generated during machining.

D

Datum: A reference point, line, or surface against which other part features are measured in CNC machining. It’s the starting point for all dimensional measurements.

Design for Manufacturability (DfM): DfM is the general engineering practice of designing products so they are easy to manufacture. The concept exists in almost all engineering disciplines, but the implementation differs widely depending on the manufacturing technology. DfM aims to minimize the complexity of manufacturing operations, reduce waste and cost, and ultimately, create a better product more quickly.

Want to improve your designs? Here are 23 tips to help.

Drilling: A cutting process that uses a drill bit to cut or enlarge a hole of a circular cross-section in solid materials. It is a common operation in CNC machining, and the CNC machine can accurately position and control the speed of the drill bit.

These tips will take your designs for CNC drilling to the next level.

E

End Mill: An end mill is a cutting tool used in industrial milling applications. It’s different from a drill bit in that it can generally cut in all directions, while a drill bit can only cut in the downward direction.

F

Fixture: In CNC machining, a fixture is a device used to securely hold the workpiece in place during machining, ensuring that it doesn’t move or vibrate, which could cause inaccuracies. The design and setup of fixtures are crucial to the machining process.

G

G Code: Also known as G-programming language, G Code is a language that controls the features of a CNC machine. Generated by a CAM program, it controls the position, speed, and tool changes, among other factors.

H

High-Speed Machining (HSM): HSM is characterized by high spindle speed and feed rate to achieve high material removal rates. It’s often used for cutting hard materials and when high accuracy and precision are required.

J

Jig: A custom-made tool used to control the motion and location of another tool. A jig’s primary purpose is to provide repeatability, accuracy, and interchangeability in manufacturing.

K

Kerf is the width of the cut or groove made by the cutting tool. In laser cutting, it’s the width of material that the laser beam removes during the cutting process.

L

Laser Cutting: This technology uses a laser to cut materials. In CNC laser cutting, the machine controls the laser cutter to achieve precise cuts and reproduce complex shapes.

Save time and money with these design guidelines for laser-cut parts.

Lathe: A lathe is a CNC machine that rotates a workpiece around a stationary cutting tool. It’s commonly used for turning, knurling, drilling, and threading operations.

M

Materials: Materials refer to the various types of metal, plastic, wood, foam, or other substances that can be shaped or manipulated by the CNC machine. Each material has different properties that affect how it can be machined.

• See the most popular metals.
• Discover the most-used polymers.

Machine Tool: A machine tool is a machine for shaping or machining metal or other rigid materials. In a broader sense, any machinery or device uses power to perform a machining operation. A CNC machine is a type of machine tool.

Machining Center: A machining center is a highly automated CNC machine capable of performing multiple machining operations in one setup with minimal human intervention. Types of machining centers include vertical machining centers (VMCs) and horizontal machining centers (HMCs).

Milling is a machining process in which a rotating cutting tool removes material from a workpiece. It can be done in varying directions on multiple axes to create different shapes, slots, holes, and impressions.

Need high-quality CNC milling services? We have you covered.

O

Offset: A modification of coordinate values to adjust for tool size, wear, workpiece dimensions, or other variables. The offsets allow the CNC machine to produce parts that meet the required dimensions.

On-demand Manufacturing: This is a business strategy in which products are built to order and often customized to individual specifications.

P

Pitch is the distance between corresponding points on adjacent threads (in threading operations) or between teeth (in milling operations).

Plunge: A movement in which the tool is moved straight down into the workpiece. This is usually the first step in a milling operation, where the cutting tool needs to reach a specific depth in the workpiece before moving in the X, Y, or Z axis.

R

Revolutions per Minute (RPM): This measures the frequency of a rotation, typically referring to the speed of the spindle holding the cutting tool. The RPM value significantly affects the feed rate calculation and overall machining time.

S

Spindle: The spindle is a critical part of the CNC machine. It holds and rotates the cutting tool, enabling it to cut into the workpiece. The speed of the spindle’s rotation (measured in RPM) can be programmed and adjusted according to the needs of the machining operation.

STEP Files: STEP (Standard for the Exchange of Product Data) files are a type of 3D CAD file used in CNC machining. They are universally compatible across various software platforms, making them ideal for sharing 3D models and design data.

Surface Finish: Surface finish refers to the part’s texture, roughness, and surface characteristics after machining. This can be critical for the part’s function, appearance, and ability to mate with other parts.

T

Taper: In CNC machining, a taper is an incremental reduction in the diameter of the cylindrical section of a workpiece. A CNC machine can machine tapers by precisely adjusting the X and Z axes.

Tolerance: In CNC machining, tolerance refers to the permissible limit of variation in a physical dimension. Tolerances are critical in producing parts, as even slight deviations from the design can lead to parts not fitting together as intended.

Toolpath: The toolpath is the path that the cutting tool follows when machining a part in a CNC machine. It is determined in the CAM software during the part’s programming.

Turning: Turning is a machining process in which a cutting tool moves linearly while the workpiece rotates. This process is typically performed on a lathe, which produces cylindrical parts.

Source industrial-quality machined parts with our CNC turning services.

U

Undercut: An undercut is an inaccessible recessed area using a standard end mill or drill bit. Specialized tools and machining strategies are often required to effectively machine undercuts.

V

Vertical Machining Center (VMC): A VMC is a machine with a vertically oriented spindle. Tools stick straight down from the tool holder, and workpieces are fixed on a table.

W

Workpiece: The workpiece is the item that is being machined. It is the starting material from which the final product will be created through machining.

X

X-Axis: The X-axis usually represents the horizontal line in a Cartesian coordinate system. In a CNC machine, movement along the X-axis is typically side-to-side.

Y 

Y-Axis: The Y-axis typically represents the vertical line in a Cartesian coordinate system. In a CNC machine, movement along the Y-axis is usually front-to-back.

Z

Z-Axis: The Z-axis represents the third dimension in a Cartesian coordinate system, offering depth (or height). In a CNC machine, movement along the Z-axis is usually up and down.

Zero Point: This is the origin of the coordinate system, where the X, Y, and Z axes intersect. It serves as the reference point for all other points in the system.

CNC Machining Made Easy with MakerVerse

The better you understand these terms, the easier it will be for you to make the most of CNC machining.

If you need clarification on something, feel free to ask. MakerVerse is your platform for sourcing industrial parts on demand, and our experts are always ready to help. You can get started by uploading your design. Our experts can ensure the machinability of the part and advise you on the best materials to use.