Widely employed in subtractive manufacturing, CNC machines are fast, reliable, and complex. With computerized numerical control, CNC mills and lathes can produce parts with complex geometries for one-off practical end-use, rapid prototyping, low-volume manufacturing, or mass production.

Because of the relative sophistication of these devices, it is not uncommon to see many different brands of equipment from workshop to workshop. That being said, every CNC milling machine will have some basic components to perform the device’s primary function. This article takes a quick stab at the basic parts of a CNC milling machine, their function, and their possible location. In no particular order, here is a rundown of the standard and most common parts of a CNC milling machine:

1. Base

The base of a CNC milling machine is a cast iron platform that supports the weight of the machine from top to bottom. The base component is a part of CNC machine in contact with the ground and may double as a tank for cutting fluids, depending on the design of the machine.

2. Turret

The turret is a component of the milling machine that allows for proper rotation of the milling head along the center of the column.

3. Saddle

The saddle lies between the table and the knee. It is responsible for facilitating the movement of the workpieces along the y-axis.

4. Frame

The frame is the structural support of the CNC machine. It could be made from cast iron and supports and dampens the machine and the effects of the machining vibrations. The frame must be rigidly secured to the group to prevent workplace injuries and excess vibration resulting in machining errors.

5. Table

The table is the part of the CNC machine that holds the job and houses the job-holding devices. The table secures the workpiece and is placed atop the saddle. It contains a number of T-slots for securing jigs, workpieces, and fixtures.

Tables are moveable and receive signals from the operator through the control panel. They may be secured via vices or clamps and allow for the movement of the workpieces on the machine’s x-axis.

6. Spindle

The spindle holds the cutting tool in place and makes rotations when necessary to mobile the tool holder. From design, the tools for milling and machining will be installed in the tapered end of the spindle. Spindles have varying revolutions per minute (RPMs), which refers to the speed capacity of the spindle.

Depending on the part to be machined and the tools used, the spindle speed may vary from job to job. Spindle speeds can toggle to match the demands and properties of the workpiece to be milled. They could be self-contained cartridges or fabricated spindles.

7. Axes

The CNC milling axes are one of the most critical components in the machine. These axes are connected to the machine’s frame, providing motion in all x, y, and z-axis. The number of axes determines the number of directions the machine can move when fabricating a workpiece. 3-axis CNC can move in 3 directions while 4-axis CNC will move in an optional 4th axis.

There are also 5-axis CNC mills, but they are not very common. The motion of the axis is directed by the g-code programming as well as manual input in the control panel.

8. Knee

The knee serves to provide additional support to the saddle and table. It allows vertical movement along the z-axis while keeping the cutting tool above the workpiece. The knee also supports the material feed mechanism of the CNC machine.

9. Column

The column is a vertical support structure that joins the base and other components of the CNC machine. It also holds the turret and houses the machine’s driving motor

10. Cutting tool

The cutting tool is the component of the machine that delivers the actual cutting action. The cutting tool is attached to the column and used to machine the pieces in the manner directed by the programming or operator’s input. The systemic action of the cutting tool on the workpiece results in the final part that matches the designer’s specifications.

11. Coolant supply tubes

In the absence of a reservoir tank at the base of the CNC machine, there will be coolant supply tubes that flow from a tank to supply coolant and cutting fluids to the machine. These supply tubes are necessary for heat control and lubrication during machining.

12. Control panel

The control panel or CNC controller is a display and control panel used to give a command to the CNC milling machine. It signals the machine’s motor on how and when to move the machine’s axes. The control panel may be considered the brain of the CNC machine. It is also responsible for interpreting input codes and programming language.

13. Arbor

The Arbor is an extension of the spindle. It is responsible for mounting and rotating the cutting tool.

14. Overhanging head

The overhanging head also referred to as overhanging arm, is used to deliver electrical supply from the machine’s motor to the mechanical arm of the spindle.

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