Choosing the Right Metal for CNC Machining
Choosing the right metal for CNC Machining involves analysing various factors. Depending on the part or product being CNC machined, the metal you choose and its properties will play a vital role in the success of the final part. For example, the metal may need to be resistant to extreme temperatures, or be resistant to bending or breaking under pressure. Corrosion resistance, workability, price, weight and cosmetic appearance all factor in when it comes to choosing the right metal.
Get It Made has written this guide to assist in choosing the best metal for your CNC machining project. This guide will cover:
Can a CNC Machine Cut Metal?
CNC machines can indeed cut metal, and are widely used due to their high precision and accuracy. Depending on the material in question and its strength and hardness, CNC machining will yield different results and finishes.
What are the types of CNC Machining?
There are various types of CNC machines, and depending on cost, material, finish quality and design, a suitable CNC machine will be used. Popular methods of CNC Machining include:
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.
CNC Machining metals
TitaniumTitanium 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 light weight as well as offering high strength, and has brilliant corrosion resistance and high temperature resistance. For this reason, it is a popular choice for aircraft industry parts, biomedical and military.
A popular grade of titanium is Ti6Al4V (also known as TC4 and Grade 5).
Stainless SteelsThere are many different grades of stainless steel, which are categorised into four main types: Ferritic, Austenitic, Martensitic, Duplex.
The most common Stainless Steel is Austenitic, which is our focus today. Their chemical structure includes Manganese, Nitrogen and Nickel, which provides good machinability and weldability. The three most common grades used in CNC 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. This stainless steel has better weldability and formability, meaning it is used for screws, machinery parts, car headers and food handling equipment.
- 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. Medical implants and surgical instruments also make use of this stainless steel. It is also implemented within the aerospace industry.
AluminiumAluminium is extremely common in CNC milling processes due to its machinability, 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. Al7075 has great properties such as ductility, toughness, high strength with good resistance to fatigue. This means it is a very common material choice for high stress structural components in aerospace.
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. Al6061 is the most commonly used aluminium grade and is ideal for automobile parts, frames and much more. Aluminium 6061 is generally seen as a general purpose aluminium, with a good strength to weight ratio, and good machinability. However, it has poor corrosion resistance when exposed to salt water and is not as strong as other aluminiums that are required for more demanding applications.
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.
BrassBrass 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. Brass is also used for electronic hardware, commercial fittings and aerospace parts. As it is a copper- zinc alloy, brass does not become brittle at low temperatures. It is a great choice pipe fittings, with excellent thermal conductivity, and its attractive colour options make it a popular option for products that require high quality finish. Brass is also one of the easiest metals to CNC Machine.
Carbon Steel 1045EN 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, nuts and other resilient mechanical parts. It is a good steel for applications requiring greater strength or hardness requirements, such as shafts, axles, bolts and studs.
D2 SteelD2 Steel is another member of the steel family and is significantly strong and durable. D2 Steel 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. Explore more of our CNC machining services on our website or check our blog. 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.