3 axis to 5 axis: CNC milling machine

3-axis to 5-axis: Comparison of CNC milling machine capabilities

3-Axis CNC Machining

3-axis CNC machining evolved from rotary filing. Here, the workpiece occupies a stationary position while the cutting tool moves across the X-, Y-, and Z-axes. The X-axis is along with the lathe table, the Y-axis is towards the front/back of the table, and the spindle that drops from the top marks the Z-axis.

It is ideal for simple tasks that do not require intricate detailing or depth. As such, it is one of the most preferred techniques for creating mechanical parts for automation. Additionally, you can also use it for cutting sharp edges, boring, milling slots, tapping, and drilling holes. 

Limitations:

3-axis machining possesses the following limitations:

It functions in a complex programming environment.

The initial capital investment and the installation costs are high.

It requires highly skilled professionals for operating and maintaining the machine.

4-Axis CNC Machining

The 4-axis CNC functions pretty much like its 3-axis counterpart. The feed is in a stationary position, and the cutting tool works on it to remove the excess and mold the desired part. 

However, as the name indicates, 4-axis machining involves an additional axis apart from the usual X, Y, and Z planes. This extra movement is present in the form of rotation along the X-axis, which forms the fourth plane – the A-axis (horizontally). However, the cutting may also take place along the B-axis (vertically). But since Horizontal Machining is considered more productive than Vertical Machining, the former is more common.

This milling technique is useful for cutting holes, cutting along an arc, or carving cutouts, especially on the sides or around a cylinder. It is also useful for high-quality precision engravings, millings, and drillings.

Limitations:

The greatest limitation of the 4-axis milling machine is its Geneva Mechanism. While the Geneva Mechanism is quite common for its simplicity, reliability, and precision, it allows the 4th axis only in principle. However, it does not support continuous machining in practicality as it possesses a fixed set of stops. Hence, the operators can only use the machine as a pure indexer. Other drawbacks include:

Quick wear and tear of the worm gear mechanism, especially during high-intensity use.

The issue of backlash can affect your accuracy or the durability of the machine.

5-Axis CNC Machining

The 5-axis CNC milling machine marks the pinnacle of innovation in 21st-century machining. It bears greater competency than its 3- and 4-axis milling machines and is a precise, fast working, micromachining powerhouse. 

In this setup, the X, Y, and Z-axes are similar to a 3-axis machine layout. The table then rotates along the A-axis, as it does with the 4-axis. However, the 5-axis machine involves the pivoting action at the joint of the table, followed by rotation along the C-axis, which defines the fifth movement.

5-axis machining allows the operator to simultaneously hit five different sides (or more!) of a part depending on the design complexities. Resultantly, the tool is highly capable of creating highly precise products and parts. Hence, it should come as no surprise that it finds wide usage in medical technology, research and development, architecture, military, automotive industry, and even creative arts. It also finds use in hole drilling at compound angles.