Choosing the Right Metal for CNC Machining
CNC milling and machining are extremely common manufacturing processes and it’s easy to see why. Compared to traditional methods, CNC (Computer Numerical Control) machining offers rapid production whilst also requiring minimal human input. Benefits of this include a more cost-efficient workforce but, more importantly, less room for human error.
Not only are parts made swiftly but CNC machining allows for extremely high levels of quality, repeatability and precision. There is also a wide range of materials that CNC machining can be used for, ranging from plastics, metals and ceramics.
There are a multitude of metals available for CNC machining. In this blog post, we're going to take a look at a selection of commonly used metals used within CNC machining. These recommendations also apply to CNC turning and multi-axis machining.
We will also determine which projects each metal are best suited to. When considering which material is right for a job, various factors must be taken into account. These include price, strength, corrosion resistance, workability and aesthetics.
Titanium is known for being a particularly strong and resilient metal whilst maintaining an excellent strength-to-weight ratio. It is highly workable and can be welded with ease. Although it conducts heat well, it possesses poor electrical conductivity. Whilst titanium responds well to anodising for a clean finish and protection, it reacts unfavourably to polishing.
Titanium is typically one of the more expensive metals to machine. Its most common uses are industrial, biomedical, military and aerospace. A popular grade of titanium is Ti6Al4V.
There is a range of stainless steel types, which are categorised into four main types: Ferretic, Austenitic, Martensitic, Duplex.
The most common Stainless Steel is Austenitic, which is our focus today. Their structure includes Manganese, Nitrogen and Nickel, which provides good machinability and weldability. Three common grades used in machining processes are:
- SS304 - This is the most commonly used stainless steel and is highly corrosion-resistant. SS304 is commonly used for producing pipes, kitchen accessories and within industrial and automotive industries.
- SS303 - This grade is often used to machine shafts, gears, nuts and bolts. SS303 is not ideal for heat-treating or cold forming due to the presence of sulphur.
- SS316 - This steel is incredibly strong, yet is easy to weld which makes it perfect for marine grade use. Again, the high resistance to corrosion makes it ideal for architectural, industrial and automotive purposes.
Aluminium is extremely common in CNC milling processes due to its workability and versatility. It also provides a modest strength-to-weight ratio.
Aluminium 7075 is a high-grade metal with excellent strength. However, its strength can make it more difficult to produce designs with more complexity. AL7075 is ideal for CNC machined parts which require sustained durability such as frames within the automobile and aerospace industries.
Aluminium 6061 however, has far better workability and is generally considered to be an economical grade. It has good atmospheric corrosion resistance but low resistance to corrosion from chemicals or saltwater. AL6061 is the most commonly used aluminium grade and is ideal for automobile parts, frames and much more.
Magnesium AZ31: Although aluminium has a good strength-to-weight ratio, AZ31 can be up to 35% lighter whilst maintaining the same strength. As you can imagine, this means it is also higher on the price scale. Lightweight and durable, AZ31 is great for use in aircraft components, power tools and laptops. However, despite good workability, it does have some flammable properties.
Brass is extremely versatile and is commonly used in plumbing systems. It also tends to be used in musical instruments as well as cosmetic applications and home decor. This is because it is highly workable and can achieve an extremely high polish, making it aesthetically pleasing. In addition to this, it is naturally resistant to saltwater corrosion and is devoid of flammable properties.
Carbon Steel 1045
EN 1045 steel is highly workable and particularly suitable for welding. This steel grade shows high levels of strength and tends to be more economical than stainless steel. Much like stainless steel 303, it is often used for gears bolts, nuts and other resilient mechanical parts.
D2 Steel is another member of the steel family and is significantly strong and durable. D2 Steels is also highly resistant to abrasion and wear. The strength and hardness of D2 steel makes it suitable for parts which need high structural integrity and resistance to bending.
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Get It Made offers a wide range of materials for CNC Machining including materials not listed above. Why not get in touch to discuss your material requirements and kick-start your project today? Arrange a CNC machining quote today and our team will respond within 24 hours.