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The Different Types of CNC Machines Explained

Different Types of CNC Machines

There are hundreds of different machines used in the manufacturing industry. Computer numerical controlled (CNC) machines are some of the most common manufacturing equipment used to make precision parts. CNC machines use a computer program that loads a digital rendering of a part using G-code or M-code. After the machinist inputs the part specifications, the tools start removing material from a workpiece to form parts.

CNC machines were originally developed in the 1940s and 50s. They quickly developed and improved their machining capabilities. The modern CNC machines we use today have revolutionized machining processes and made manufacturing precision parts significantly more efficient.

The main two groups of CNC machines are 3-axis machines, and multi-axis machines. This article will go over the basics of the different machines and how they’re used to make precision parts and components.

CNC Machining diagram

3-Axis CNC Machines

3-Axis milling machines

3-axis milling machines are the most common type of 3-axis CNC machine. These can produce most part shapes and features, and they’re also relatively easy to program and operate.

During CNC milling, the workpiece, or raw material is held stationary on the machining table or in a vice. A cutting tool is attached to a spindle that moves across the 3 axis (X, Y, Z). The cutting tool and spindle rotate at a very high speed and move against the raw material to form the shape and physical features of the part. 

For most parts, several rounds of cutting are needed to form the part. The first round of cutting gives the part its general shape. That’s followed by finishing rounds that have greater accuracy and form the finished part. 

Because the spindle is limited to moving on the 3 axes, some surfaces of the part are unreachable. That means the part may need to be rotated and additional rounds of cutting are needed. That increases the manufacturing times, and increases the chances of mistakes.

CNC Turning Machines / CNC Lathes

CNC turning machines and CNC lathes are the same type of machine. They can produce parts at a much faster rate compared to CNC milling machines. That means they produce parts at a lower cost per part. 

Instead of the cutting tool being held in the spindle, the raw material is held. Then, the cutting tool forms the shape and features of the part. 

Because the part is rotating, CNC lathes are used to machine cylindrical parts. To overcome this limitation, some features of CNC turned parts are also milled.

Compare: CNC Turning vs Milling

5-Axis CNC machines

These machines can rotate on the same X, Y, and Z axis as a 3-axis machine. What makes these unique is the ability to rotate on an additional 2 axis: the A and B axis. 

The additional two axes of movement allow the machines to make more complex part designs. But, these machines are more expensive and require more machining knowledge, so the parts can be more expensive.

Indexed 5-axis CNC machines

With an indexed 5-axis machine, the cutting tools can move along the x, Y, and Z axes automatically. But, the A and B axis aren’t able to move during the cutting operations. Once the cutting is done, the machine can rotate on the other two axes without human intervention. There’s a slight pause in the process, but no manual work needs to be done. Unlike a 3-axis machine, the part doesn’t need to be rotated or repositioned.

Continuous 5-axis CNC machines

These machines have the true free-flow operation of a 5-axis machine. They have the same setup as an indexed milling machine, but they can move all 5 axes while the machining is happening. These increased capabilities come at a higher cost. 

Mill turning CNC centers

These machines are very similar to CNC turning machines. But, they’re also equipped with CNC milling tools. 

The part being machined is attached to a spindle that can rotate the part like a turning machine, or keep the part in a specific spot like a CNC mill. 

Both lathe and milling cutting tools are used to remove material and form the part. One type of these machines is called a Swiss style lathe. These machines typically offer greater accuracy. Mill turning centers take advantage of the high productivity of a CNC turning machine, and the flexibility of CNC milling machines.

Spex is a precision machine shop that was established in 1946. We use a variety of CNC machines and other processes to manufacture custom precision metal parts. Reach out to our team to get a quote on your next project. 

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