CNC machining difference between 3 Axis , 4 Axis,and 5 Axis

 CNC machining is a manufacturing process that utilizes computerized controls to operate and manipulate machine and cutting tools to shape stock material—e.g., metal, plastic, wood, foam, composite, etc.—into custom parts and designs.

An axis reference is used to describe a CNC machine that works with multiple axis points. The machine operates in the XYZ plane with at least three axes: X-axis (vertical), Y-axis (horizontal), and Z-axis (depth). The 4th axis is with the A axis (rotation around the X-axis), and the 5th axis includes the B-axis (rotation around the Y-axis).

So what are the differences between 3 axes, 4 axes, and 5 axis CNC machining, the following provides an explanation of it.

3 Axis CNC machining

3-Axis machining is the most simple type of machining, where the workpiece position is fixed, while the cutting tool moves along the X, Y, and Z linear directions to cut away material. This is good for the parts that don’t need a lot of depth and detail. Only one side of the part can be machined for a single fixture setup. 3 axis machining is used to produce mechanical components normally and is suitable for:

• Automatic/interactive operation
• Milling slots
• Drilling holes
• Cutting sharp edges

4 Axis machining

4-axis machining means that a workpiece is processed in an equal manner as a 3-axis system, however, has an extra rotary movement around the X-axis, which is called the A axis. This rotation permits the workpiece to be cut around the A. When holes or cuts need to be made on the sides of a workpiece, this machining method is useful. This additional 4th axis (A axis) allows a workpiece to be mechanically flipped over, so the machine can cut away material from both sides. 4-axis machining is multifunctional and can be used for:

• Intermittent cutting
• Continuous cutting
• Engraving curved surfaces

5 Axis CNC machining​

5-axis machining means that a workpiece can be processed from five sides at one time. In addition to movements along the X, Y, and Z-axis, the machine utilize 2 out of the 3 possible rotation axis(A, B, C), the A, B, and C axis perform a 180° rotation around the X, Y, and Z-axis Normally, the A-axis and B axis will be used as rotational axis on the 5-axis CNC machining. 5-axis machining is one of the multiaxis machining.

There are two types of 5-axis CNC machines normally, 3+2 machines, and fully continuous 5-axis machines.

In 3+2 axis machining, the two rotational axes perform independently to each other, which means that the workpiece can be rotated to any compound angle with respect to the cutting tool. However,  it is impossible to rotate both axes at the same time. 3+2 machining can manufacture especially complicated 3D geometries.

Fully continuous 5-axis machining allows simultaneous rotation of two rotary axes, at the same time as machining and the cutting tool moving linearly in XYZ coordinates. The continuous 5-axis machining can produce very complex 3D geometry, not only planar compound angled features but also complicated curved 3D surfaces, giving us the capability to produce parts normally reserved for molding processes.

This type of machining is used in the automobile, aerospace, and boating industries. 5 axis machining is beneficial when components are very complex and with high precision. This includes:

• Accuracy Features
• Increased productivity
• Higher quality finishes
• Cutting intricate details
• Machining complex geometry

5-Axis CNC machining aluminum part

At CYmanufacturing, we can offer both 3-axis, 4-axis, and 5-axis CNC machining services, If you need assistance manufacturing your machined parts. Please don’t hesitate to contact us.

Surface Finishes for CNC Machining Parts

  There are a number of surface finishing techniques to give CNC machined parts the desired professional finish. It can change the appearance, surface roughness, hardness, and chemical resistance of the machining parts. Below is a quick summary of the most common surface finishes for precision machined components from CNC machining shops.

1. As-Machined

   An As Machined CNC machining part surface finish does not require any post-processing, but the tool marks will be shown on their surface, thus it is not perfectly smooth. The standard surface roughness of an as-machined part is 3.2 um. However, additional smoothing and polishing can reduce the machined texture to surface roughness of 0.4 um. This finish is very cost-effective and most suitable for prototypes and jigs and fixtures.

2. Bead Blasting

   Bead blasting is the operation of shooting the blast media against a surface to affect the surface finish by using compressed air typically. It results in adding a uniform matte or satin surface finish on a CNC machined part.

This process relies on using small beads to remove incremental amounts of material from the CNC machined part’s surface. As the resulting surface roughness is not guaranteed, so critical surfaces or features (like holes) need to be masked to avoid any dimensional change.

Bead blasting is a post-process to get a smooth finish, but will affect the dimensional accuracy of the parts slightly, Therefore, it is used mainly for visual purposes or aesthetic applications without tight tolerance requirements.

3. Anodizing

   Anodizing is a process that is used to increase the thickness of the natural oxide layer on the surface of metal parts, it does not need to use heavy metals nor does it produce toxic waste, so it is an environmentally friendly process, also it meets the environmental and safety directives of the RoHS.

In the anodizing process, an electrochemical reaction consumes the material on all exposed surfaces of the part and converts it into hard metal oxide, typically for aluminum or titanium. And the anodic coating grows in both directions equally and it is electrically non-conductive, so a mask needs to be applied to the surfaces with critical dimensions (like threaded holes) or the surfaces that must remain electrically conductive to prevent them from anodizing.

The main advantages of anodizing CNC machined parts are with high aesthetically pleasing surface and more durable. For more information about aluminum anodizing, please click here.

4. Powder Coating

   This is a process where powdered paint is sprayed onto a part which is then baked in an oven. It adds a thin layer of strong, wear and corrosion- resistant protective polymer on the surface of the machined part. Powder coating is compatible with all machining metal materials, some manufacturers also combine the powder coating process with bead blasting to create parts with a smooth finish and excellent corrosion resistance.

This finish is ideal for end-use products, due to some of the advantages listed below:

• Strong, wear and corrosion resistant
• Higher impact resistance
• Compatible with all metal materials
• Multiple colors available

But the powder coating will change the dimension of the part, so it doesn’t fit for tight tolerance part, also it is difficult to apply to the internal surfaces.

5. Passivation

   The passivation process is a method of improving the corrosion resistance of stainless steel machined parts by removing ferrous contaminants like free iron from their surface, restoring them to their original corrosion specifications.

Passivation is a post-processing best practice for newly-machined stainless steel parts and components. Benefits include:

• Chemical film barrier against rust
• Extended life of the product
• Removal of contamination from the product surface
• Reduced need for maintenance.

To passivate stainless steel machining parts, they must be submerged in a chemical solution of citric acid or nitric acid for a certain period of time and at a certain temperature. Passivation is a chemical treatment and not an electrolytic process, it does not depend on electrochemical reactions, unlike electropolishing or anodizing. And passivation is not a method to remove oxide scale from machined parts after heat-treating or welding. Also, passivating stainless steel does not change the color or surface appearance of the metal. This process is not necessary for items that will be painted or powder-coated.

You can passivate stainless steel to improve its corrosion resistance, but not all grades are suited for this process, and some parts may require additional cleaning operations beforehand.

General Rule of Thumb for Surface Finish on CNC Machining Parts:

• An as-machined finish is best for the machining parts with tight tolerances, where aesthetics is not the major concern.
• Bead blasting is best for machined parts with matter uniform finishes, when maintaining dimensional tolerances is not the key issue.
• Anodizing Type II is good for the titanium and aluminum parts which need aesthetically pleasing.
• Anodizing Type III is better for engineering applications, where very high wear resistance and surface hardness are required.
• Powder coating is good for the machined components which need high-impact strength or it can not be anodized.
• The passivation process is mostly for improving the corrosion resistance of stainless steel CNC machined parts.