xiehe model

You'll hear a lot of talk about axes when choosing a CNC machine for your project. CNC machines tend to operate with 3, 4 or 5 axes, with 4 and 5 axis CNC machines being advertised as the powerful types.

But what exactly do 4-axis and 5-axis mean? If the machined part has three dimensions - height, width and depth - where do those extra two axes come from? Is it really worth it to choose 5-axis machining over cheaper alternatives?

What is 3+2 axis CNC machining?

A subtype of 5-axis machining is 3+2-axis machining, which, as the name suggests, is a middle ground between 3-axis and 5-axis. Nonetheless, it is a fast and efficient form of 5-axis machining, sometimes referred to as positioning 5-axis machining.

For 3+2 axis machining, the angle of the tool does not change when the spindle or table rotates around the two additional axes. Therefore, the cutting tool is not always perpendicular to the part, which does not always produce a perfect cut. (However, there is a form of 3+2-axis machining, called indexed 3+2-axis machining, in which the tool angle is manually adjusted between cuts.)

Five-axis machining in which the tool can always remain perpendicular to the part is called continuous or simultaneous five-axis machining. The process can provide an excellent surface finish and allows access to hard-to-reach areas, but is slower than 3+2 axis machining.

The advantages of 4-axis

5-axis CNC machining offers many benefits, including increased accuracy, reduced setup time and the potential to machine more complex parts.

Other specific advantages depend on the type of machine configuration—whether it’s a trunnion or rotary-head CNC machine, or anything else—and whether the machine uses 3+2 axes or continuous 5 axes.

Generally speaking, 3+2 axis machining has the following advantages:

1. fast processing

2. Easy setup

3. There is little chance of tool interference

Continuous 5-axis machining has the following advantages:

1. Excellent surface finish

2. better parts access

3. Reduce tool wear

 A trunnion setup can benefit:

1. better parts access

2. larger size

3. more torque

 A rotating head setup can benefit:

1. Heavy parts (the table does not need to be moved)

2. There is little chance of tool interference

 4-axis and 5-axis CNC machining applications

 4- and 5-axis machining centers are especially useful for creating molds with deep cavities, creating complex 3D shapes, and machining on sloped surfaces of parts without compromising accuracy.

 Although 5-axis machining can be used for a variety of parts, it is especially predominant in the production of parts such as impellers and turbine blades, which have contoured surfaces that are not suitable for 3-axis machining.