In CNC machining, what is the difference between 3 axis, 4 axis and 5 axis? What are their respective advantages? Milling is an important technique used in CNC precision machining having applications for medical, aerospace, optical, as mechanical parts. Milling uses rotary cutters to remove material from a workpiece by feeding the workpiece at an angle to the axis of the tool. The axes that a milling machine has, determines the type of work and the locations in which it can be done on the workpiece. Here we look at 3, 4, and 5 axis machining, their differences, and which to choose for your part.

WHAT IS 3-AXIS MACHINING?

The most simple type of machining, where the workpiece is fixed in a single position. Movement of the spindle is available in the X, Y and Z linear directions.

3-axis machining

3-axis machines are typically used for machining of 2D and 2.5D geometry. Machining of all 6 sides of a part is possible in 3 axis machining but a new fixturing set-up is required for each side, which could be expensive (more on that below). For a single fixture setup, only one side of the part can be machined.

A unique setup is required for each side of a part

Many complex and practical shapes can be manufactured by 3 axis CNC milling, especially when in the hands of a world class CNC machining facility. 3-axis machining is best suited to manufacture of planar milled profiles, drillings & threaded holes in-line with an axis. Undercut features are possible with the use of T-slot cutters and Dovetail milling cutters.

However, sometimes the designed feature physically cannot be manufactured by a 3-axis machine, or the feature might be more economically viable to machine with a 4 or 5 axis machine.

Features not possible in 3 axis milling include any features on an angle to the X-Y-Z co-ordinate system, even if the feature itself is planar. There are two types of angled features you can design, and understanding the distinction between them is important when designing parts for CNC milling.

ANGLED FEATURE

This is a feature machined on an angle to one of the X, Y or Z axes. For example, the planar milled surface below is at 45° to the X-axis e.g. a rotation of the A-axis.

Milled feature angled in a single plane at 45°

COMPOUND ANGLE FEATURE

This is a feature machined on an angle to two axes. For example the planar milled surface below is machined at a 45° angle to the X-axis, and a 30° angle to the Z axis.

Both angled and compound angle features cannot be machined by 3-axis CNC machines.

Milled compound angle feature in two planes: 45° about X-axis, 30° about Z-axis

4 axis machiningWHAT IS 4-AXIS MACHINING?

4-axis milling involves the same processes involved in 3-axis machining, where a cutting tool is used to remove material from a piece to create the desired shape and profile. However, in the case of 4-axes machining, milling is performed on an additional axis. A 4-axis CNC machine operates on the X,Y and Z axes like a 3-axis machine, but it also includes rotation around the X-axis, which is called the A-axis. This is the 4th axis that’s added to our machining process. In most cases, the workpiece will be rotated to allow for cutting to occur around the B-axis.

4-axis milling is useful when holes and cut-outs need to be made in the side of a piece or around a cylinder. They can provide quick and efficient work based off computer numerical inputs for precise results.

WHAT IS 5-AXIS MACHINING?

5-axis machining involves all the axes of 4-axis machining, with an additional rotational axis. 5-axis milling machines are the best CNC milling machines available today, capable of creating precise and intricate parts for artificial bones, aerospace products, titanium pieces, oil and gas machine parts, car molds, medical, architectural, and military products. The 5th axis in 5-axis milling machine is around the B-axis, which rotates around the Y-axis in the X-Y-Z plane. This multidimensional rotation and tool movement allows for B-axis unparalleled precision, finish and speed in the production of a piece. 5-axis machining can create very complex parts, which is why it is so important for high level uses, such as aerospace applications.

However, 5-axis machining is also becoming more popular because it offers the option for single-step machining (reducing lead time), allows better access to part geometry, and improves the tool life and efficiency of the process by tilting the table for the ideal cutting position.

So which type of machining should you choose for your project. It all comes down to your unique requirements, budget and timeline. For expert advice, talk with one of our professional precision engineers to find the right match for your needs.

The possibilities of simultaneous 5-axis machining

5-axis machining gives designers a huge level of flexibility to design very complex 3D geometry. Understanding the possibilities of each type of CNC machining is essential in design of CNC machined parts. If your design needs the use of a 5-axis CNC, make the most of it! Which other features could benefit from the capabilities of 5-axis machining?

Frequently asked questions about mechanical equipment

What is the difference between 3-axis and 5 axis?

The main difference between 3-axis and 5-axis milling machines is that the workpiece can be worked on from three axes with the former and five axes with the latter. Both are highly versatile, automated, and replicable production processes that will enable you to quickly and cost-effectively create accurate components

What is 4th and 5th axis?

The 4th axis denotes the inclusion of an A axis (rotation around the X axis), and the 5th axis denotes the B axis (rotation around the Y axis). The number of axes on a CNC machine determines the type of work it can do, the level of detail it can cut, and the workpiece locations it can manipulate.

What is the difference between a 2 3 and 4 axis CNC router?

The primary distinction between the two is that, unlike 3-axis machining, the 4-axes machining process provides an additional axis of rotation besides the regular 3-rotational axis. A user can conveniently machine four sides of a component for a single fixture setup

What does 5 axis mean?

The term “5-axis” refers to the number of directions in which the cutting tool can move. On a 5-axis machining center, the cutting tool moves across the X, Y and Z linear axes as well as rotates on the A and B axes to approach the workpiece from any direction.

Please refer to our other article on how to find the right 5-axis parts manufacturer in China

Get in touch with us to see what is possible!