CNC machining is a process that uses computer-controlled machinery to cut, shape and form parts. It can be used for several different applications, including 3D printing, mold making, and prototyping.

To create an accurate surface finish on your CNC machine part, you need to know what kind of surface finish it’s capable of achieving.

There are three main types of surface finishes that CNC machines are capable of producing:

  • Raised (aka “positive”)
  • Flat or low relief (aka “negative”)
  • Rough machined

How to Get the Best CNC Machining Surface Finish

CNC machining is used to create a range of products, from small parts to large machinery which is why you should always consider surface finishes when CNC machining any kind of material. Here are seven ways to get the best surface finish possible on your products:

1. Use the Right Material and Design

Choosing a suitable material is an important part of getting a good surface finish because it affects how smooth a surface can be machined, how easily it can be polished, and how well it retains its luster after polishing.

For example, aluminium has a naturally high coefficient of friction that makes it difficult to machine without leaving scratches on the workpiece’s surface. If you want to make sure that your parts have smooth surfaces, consider using steel or plastic instead.

When designing your part or parts, consider their function in addition to their appearance. If they are going into an engine or other mechanical apparatus where they will rub up against other parts repeatedly over time, they may need a higher degree of abrasive resistance than if they were simply decorative items such as handles or knobs where only occasional contact occurs with other objects such as fingers or hands.

2. Use Custom Finishes

The best way to achieve the highest level of surface finish is to use custom finishes. These are typically done with a diamond abrasive wheel, which leaves a very smooth and shiny finish on your part. This type of finish is ideal for applications where you need high-quality pieces that will last a long time.

The difference between conventional or standard finishing techniques and custom finishes is that the latter usually leaves a much smoother surface than the former can provide. Abrasive wheels used in this way are specially designed for specific metals, so they can be used in different ways depending on whether you are working with aluminium or steel.

Achieving great results depends on what kind of material you’re working with at any given moment.

3. Always Consider Your Application

If you are making a part that is going to be used in an industrial environment, it might need a more durable finish than if it were going into an office setting. Some applications require a certain degree of smoothness or accuracy to function properly, while others require very little surface finish at all.

Knowing your application will help determine the right surface finish for your part and how much time and money should be spent achieving that finish level.

4. Use the Right Cutting Tools

There are a few factors that affect the surface finish of your CNC machined parts. The first thing you need to do is ensure that the cutting tools are sharp and in good condition.

Tools should be the right size for the job; too big or too small will result in rough edges and poor-quality parts.

The tool itself shouldn’t be too worn out or so new that it slices through without any resistance (this can lead to chipping).

5. Use the Bead Blasting

Bead blasting is another process that can be used to achieve a smooth finish on your CNC machined parts. Bead blasting uses particles of aluminium oxide to remove material, while sanding uses silicon carbide, which is softer than aluminium oxide.

Bead blasting works by using compressed air to propel the abrasive particles toward the surface being worked on. The movement of these particles creates friction between them and your part, which results in material removal from your workpiece’s surface.

6. Use the Ceramic Coating

Ceramic coating is a chemical process that deposits a ceramic layer onto the surface of a metal. The ceramic coating protects the metal from corrosion and wear. It’s often used in the automotive industry to protect parts such as piston rings, bearings, and seals from wear caused by friction and heat.

Ceramic coatings are also used in medical equipment to prevent corrosion or rusting of surgical instruments, implants, or other devices that come into contact with blood.

Ceramic acts as an excellent lubricant on some surfaces because it has a low coefficient of friction (COF), which helps prevent galling between moving parts.

7. Use Lower Spindle RPMs

Another way to get a smooth surface finish is to use lower spindle RPMs. This will generally result in less chatter and vibration, which can lead to a more consistent tool life as well as a better surface finish. However, it also means that the process takes longer because you’re taking fewer cuts per minute.


There are many options for surface finishing your CNC machined parts. It all depends on what type of finish you want and how much time you want to spend on it. The most important thing is that you choose an option that will work best for your business and ensure the quality of your goods.


Invest in a good quality CNC Machine. We offer a range of quality Multicam CNN machines either NEW or REFURBISHED, to suit your budget.

Contact our expert team today who can advise you on the best best Multicam CNC to suit your requirements or take a look at our INSTOCK and REFURBISHED CNC Machines here:

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