Difference between 3-axis 4-axis and 5-axis CNC mill

How many axes are in a CNC machine? Know the difference between 3-axis, 4-axis, and 5-axis CNC machines

Machining is the favoured approach for building high-precision components for various industries. It removes shavings from the raw material to make the required product. The industrial landscape has evolved with time, moving on from manual approaches to automated CNC machines.

A CNC machine uses programs (computer numerical control) for speedy, efficient production. It integrates numerous cutting tools like a bull-nose end mill, keyseat, and Dovetail cutters. From aerospace to automobiles, and electronics to construction and defense, multifaceted sectors opt for CNC machining.

These machines can have up to six axes: X, Y, Z, A, B, and C. They relate to the possible range of motion.

The number of axes helps industries choose between 3-axis, 4-axis, and 5-axis CNC machines.

3-axis

3-axis machines affix the workpiece in position. The spindle can move in X, Y, and Z directions, but the direction of the cutting tool remains unchanged.

They involve frequent fixture setups for different sides, making 6-side machining expensive and cumbersome. Components angled to X-Y-Z (single or compound) pose a challenge.

4-axis

As the name implies, they use four axes: X, Y, Z, and an additional A axis (rotation around X). Each fixture setup can machine four sides. In 4-axis CNC machining, the cutting tool can also move.

Depending on the requirements, you may use continuous machining (simultaneous cutting and rotation of A-axis) or indexing-based (cutting commences after selecting axes rotation).

5-axis

Finally, this high-quality, productivity-enhancing machining equipment uses two of the possible three axes: A and C or B and C. You can choose 3+2 (positional) or fully 5-axis machines.

The former is excellent for intricate components, using both axes rotating independently of each other but not parallel to machining. Generally, the cutting tool angle does not change with the spindle. But you may use indexed 3+2-axis machining to adjust this (manually) between cuts.

Fully 5-axis machines can rotate both axes concurrently with the cutting tool. A 5 axis lathe can produce complex and accurate 3D shapes for aerospace and boating (impellers, turbine blades, etc.). Planar, angled, and curved shapes are all possible with a brilliant surface finish.

Note: 6-axis CNC machines exist but primarily work for volume machining at excellent speed and efficiency.

Does the number of axes affect the capabilities and versatility of CNC machining?

The axes determine the possible movements and hence, the complexity of the cutting and shaping. The structure of these machines and the kind of product you can machine differ.

For instance, in 3-axis CNC machines, the cutting tool stays at a fixed angle. Machining hard-to-reach areas gets challenging. The limited axes also necessitate more setups, lowering productivity.

More axes improve the versatility of supported materials. Sturdier substances can get approached at convenient angles.

In which applications only 3-axis CNC machining is preferred?

It suits small-factory environments for planar components, drilling, and threaded holes. If the depth isn’t steep, this equipment can create slots, sharp edges, and undercuts.

3-axis lathes affordably build motherboards, semiconductors, hydraulic equipment, gearboxes, etc.

Application wise comparison of 3-axis, 4-axis, and 5-axis machining

In general, 3-axis machines are ideal for tasks that don’t need excessive precision, like spindles, sanding belts, drills, etc. But 4-axis machines build intricate 3D shapes and can also mill/engrave tilted and curved surfaces. They create complex components like cam lobes, angled parts, cylinders, and helixes.

5-axis machining is ideal for sectors demanding extreme accuracy, like medical, aerospace, defense, and oil and gas. It translates into good production speeds and volumes.

Under which conditions is a 4-axis machine highly recommended?

4-axis machines can be more cost-effective than 3-axis ones as the fixture setups/changeovers are fewer. Also, quality assurance is cheaper due to higher accuracy and limited scope for human error. Factories can choose between vertical/horizontal and continuous/indexed machines. Simultaneous 4-axis machining works for curved features.

These machines can create complex parts and are better picks than 5-axis ones for tighter budgets.

3 axis vs 4 axis vs 5 axis CNC advantages

Benefits Comparison: 3 vs 4 vs 5 axis CNC

Is there any cost & time difference between a 3-axis, 4-axis and 5-axis CNC mill?

The difference between 3-axis 4-axis and 5-axis CNC mill centers on the complexity of motion of the workpiece and the tool. Thus, 5-axis machining is the costliest, creating finished products with top-notch accuracy and precision. The time taken by 5-axis machining is also the least since multiple sides of the workpiece get processed simultaneously.

Different CNC machines cater to diverse requirements; one size won’t fit all. We advise selecting the best fit based on your manufacturing requirements, complexity, and budget.