The Ultimate Guide to Choosing CNC Material for Machining

Posted on February 1, 2021

Choosing CNC materials for machining can be difficult. Machinists can choose from a wide selection of materials. Face with so many materials, it can be difficult to choose the right one.

We have created an in-depth guide to help you choose the right material for machining. Our guide will help narrow your material options. Furthermore, it will simplify your search and help you get the best result for your CNC machining.

In our guide, we will break down the factors you should consider when choosing materials. Furthermore, we will explore the benefits and properties of common materials.

Factors to Consider When Choosing A CNC Material for Machining

Prioritise part requirement

When selecting your materials, prioritise your part’s requirement.

Do you need a metal with exceptional mechanical properties? Then, titanium alloy might be the right fit for you.

Do you need a metal that you can machine quickly and conveniently, like Aluminium 6061?

Weigh all the factors before selecting your materials.

Focus first on the essential properties your material must have.

This method will help you reduce your material options down to a workable number. Below, we have listed the properties you may want to consider when choosing a material:

  1. Environmental properties – For many machinists, this will be a top priority. Some examples include heat and cold resistance; UV tolerance and flame retardance.

Ensure that the material you choose is suited to the application of your part.

For example, a part for a medical device may have to tolerate the high heat of an autoclave. So, such a part would require a material with high heat resistance.

  • Cost – Cost can vary greatly depending on which material you choose. Consider your available budget before selecting a material. Some materials are more economically viable than others.
  • Mechanical properties – Does your part need to be rigid or flexible? Does your part need to possess compressive strength or tensile strength? Some materials meet these requirements more than others.
  • Electrical properties – this covers a wide range of factors. Depending on the application, your part may need to conduct or insulate. Alternatively, your part may need to dissipate static.

Now, we will compare the benefits of common materials:

1.     Benefits of Brass for Machining

Brass is a metal alloy with excellent electrical conductivity and good machinability. Thanks to these two properties, brass is ideal for applications that require low friction.

Additionally, brass is one of the most cost-efficient materials to machine.

Brass plays a part in a variety of industries. For example, some industries include consumer goods, medical and electrical.

Brass C36000 is a material that possesses high corrosion resistance and tensile strength. It is used for high-volume applications, as it is one of the easiest materials to machine.

1.     Benefits of Copper for Machining

Similar to brass, copper also possesses excellent electrical conductivity. Furthermore, copper has high corrosion resistance, making it difficult to rust. 

Copper is very easy to machine. Due to its conductivity, copper is malleable. So, machinists can easily shape copper when CNC machining. 

Copper is suitable for a variety of applications. For example, some applications include valves, radiators and hydraulic tubing.

You should be aware that copper is weak against certain chemicals such as:

  • Halogens sulphides
  • Ammonia solutions
  • Acids

2. Benefits of Aluminium for Machining

Aluminium alloys have an excellent strength-to-weight ratio. Furthermore, they possess a high thermal and electrical conductivity and natural corrosion resistance.

Aluminium alloys are the most economically viable material. Firstly, because they have a low bulk cost. Secondly, because aluminium is easier to machine than other materials.

You can use aluminium in a variety of applications, including spline shafts, gears and other similar parts.

Aluminium is a versatile metal with a lot more advantages:

  • Recyclability
  • Lightweight
  • Electrical and thermal conductivity
  • Reflectivity

Aluminium 6061 is the most common aluminium alloy. It possesses excellent machinability and a superior strength-to-weight ratio.

Aluminium 6082 shares similar composition and properties to 6061. However, it is more commonly used in Europe, as it complies with British Standards.

3. Benefits of Stainless Steel for machining

Stainless steel alloys have:

  • High strength
  • Excellent corrosion resistance and wear
  • High weldability and machinability
  • Good ductility

You can use stainless steel for a variety of applications. For example, some of these applications include surgical equipment, electronic hardware. Furthermore, this material is also useful for aerospace and automotive applications.

The most common stainless steel alloy is stainless steel 304. 304 has good machinability and excellent mechanical properties. It is resistant to most corrosion.

4. Benefits of mild steel for machining

Mild steels have good mechanical properties and high machinability and weldability. Due to their low costs, mild steel is usually used for general-purpose applications. For example, some of these applications include manufacturing for jigs and fixtures.

Unlike stainless steel, mild steel is susceptible to corrosion and chemicals.

Mild steel 1018 is the most commonly used alloy. It possesses great toughness, strength, hardness, weldability and machinability.

Overview of Common Plastics for CNC machining

Benefits of PVC for Machining

PVC possesses exceptional resistance to chemicals, flame and corrosion. Furthermore, it is more affordable than other CNC machining materials. So, it is a cost-effective option for a variety of applications.

Benefits of Delrin for Machining

When it comes to machining parts that require high precision and excellent dimensional stability, Delrin is a perfect choice.

Benefits of Nylon for Machining

Generally, Nylon is easy to machine, and it offers moderate flame resistance. Furthermore, Nylon possesses excellent mechanical properties, abrasion resistance and good impact strength. Thanks to these properties, Nylon is perfect for many engineering applications.

For example, CNC-machined Nylon is typically used for insulators, bearings and injection-moulding.

In CNC machining, the most commonly-used grade of Nylon is Nylon 6 and Nylon 66.

At Glassworks Engineering, we supply CNC machining services to cater a wide variety of materials. Are you looking to receive subcontract machining services? Get in touch today.

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