CNC Machining Metals
A wide selection of materials for CNC machining available in stock.
Metals tend to be heavy owing to the densely packed structure. Even so some of the non-ferrous alloys offer exceptional strengths-to-weight. In applications where thinness is critical. metals outperform the other material groups. Titanium alloy, for example, performs well at reasonably high temperatures – although metals are prone to expansion and contraction, which can cause problems – and has excellent co corrosion resistance. As a result, it is the material choice for demanding aerospace applications and has found its way into consumer products.
Metal CNC Machining Service
Material
Material Group
Cost
ALUMINIUM
Aluminium – Grey (6061)
Aluminium – Grey (6082)
Aluminium – Grey (7050)
Aluminium – Grey (7075)
£
STAINLESS STEEL
Stainless Steel – Grey (303)
Stainless Steel – Grey (304)
Stainless Steel – Grey (304L)
Stainless Steel – Grey (316)
Stainless Steel – Grey (316L)
££££
If you require a particular material that is not listed, please contact a Geomiq sales representative or email: [email protected]
What Metals Can be Machined on a CNC machine?
A wide range of CNC materials can be machined on CNC machines, and metals are no exception. CNC machines are a fantastic choice for making 3D metal parts due to their high precision and accuracy.
Metals suitable for machining have specific mechanical properties, including: strength; flexibility; and hardness. Differences in properties between metals and alloys result in a range of machinability – some metals and alloys are easier to machine than others.
The choice of metal depends on a wide range of factors (which we’ll get to later) but when it comes to cost it can generally be assumed that the harder it is to machine a metal, the more it will cost. This is because the machining process will take longer. Also the cost of raw material can have an effect on the overall cost of a part.
We will explore the range of metals that Geomiq’s CNC partners can machine and discuss what factors you should consider when choosing a metal.
Aluminium
Aluminum is considered to be the most cost-effective metal when it comes to CNC machining. This is because it has high machinability, is generally inexpensive, and has a great strength-to-weight ratio. This means that aluminium parts can have a variety of applications and can be made quickly at a lower cost.
Aluminium 6061 is considered an economical grade that offers fantastic workability and machinability. It is seen as a general-purpose grade and therefore has many applications. Whilst this grade has good atmospheric resistance, it does not have good chemical or saltwater resistance.
Aluminium 7075 grade has a wide range of useful properties such as ductility, high strength, and fatigue resistance. Whilst its high strength makes it an attractive grade for the aerospace and automotive industries, it is one of the more difficult grades to CNC machine. This grade is therefore more suitable for machining less complexed parts.
Stainless Steel
Whilst it does not have the same high machinability as aluminium, stainless steel does maintain good machinability. When you combine this with it’s relatively low raw material cost, stainless steel can be an economically viable metal to use for your part.
SS304 is the most common stainless steel and is used in a variety of household applications such as kitchen utensils and appliances. Due to its good weldability and formability SS304 is also used in pipes and machinery. Geomiq also offers SS304L which has reduced carbon.
SS303 grade is often used in shafts, gears and aircraft fittings due to its durability and corrosion resistance. It is not hardenable through heat treating processes due to the presence of sulphur.
SS316 grade is incredibly strong and corrosion resistant. It is often used for specialised applications such as medical implants and in the aerospace industry.
Steel
Other grades of steel and steel alloys can be a more economical option when compared to stainless steel. Whilst other steels do not offer the same corrosion resistance as stainless steel, they can offer other similar properties.
Steel alloy 4140 is a low alloy steel that contains manganese, chromium, and molybdenum. It has excellent high fatigue strength, toughness, and impact resistance properties, making it an attractive alloy for many applications and industries. This alloy is a more economical choice when compared to stainless steel.
Titanium
Titanium is the most expensive metal to CNC machine that Geomiq offers. This is partly due to its low thermal conductivity and high strength that give it low machinability. Combining this with a high raw material cost is what makes titanium so expensive to machine.
Geomiq offers Grade 5 Ti6AI4V titanium, the properties include: an excellent strength-to-weight ratio, chemical and temperature resistance. These properties make titanium suited for specialised applications in extreme operating environments which is why it is used extensively in medical, aerospace, and high-end automotive applications.
Brass
Brass is an alloy metal formed of copper and zinc. It therefore has high machinability, however the slightly higher cost of raw material increases the overall cost of machining. Brass however does hold its value as scrap.
The properties of brass include: medium hardness and high tensile strength – this makes it a good choice for electrical, medical, and automotive applications.
Copper
Copper has excellent machinability; however, the high cost of material brings up the overall cost of machining. Copper is popular for use in electrical products due to its high electrical and thermal conductivity.
Magnesium
Magnesium is considered one of the easiest metals to machine due to its high thermal conductivity and mechanical properties. Magnesium is also one of the lightest structural metals, up to 35% lighter than aluminium, making it great for automotive and aerospace applications.
However, machining magnesium does pose a risk as it is a flammable metal. While it is difficult to ignite a workpiece on the machine, the dust and chips produced by the cutting tool pose a significant fire risk. Magnesium can burn underwater, CO2, and nitrogen, so extra care must be taken with the unwanted material from manufacturing processes.
Genomic offers Magnesium AZ31, which has excellent machinability and is considered an aerospace-grade.
What Types of CNC Machine Can Machine Metals?
Most types of CNC machine can cut metals if they are set up and have the proper tooling and power to do so. At Geomiq, we offer CNC Milling and CNC Turning for metal parts.
How do you optimise a metal part for CNC Manufacture?
It is essential to consider several factors when designing your part for CNC manufacture to get the best result.
The factors to consider before uploading your CAD file include:
- Vertical Radii
- Cavities
- Minimum Wall Thickness
- Hole Diameters
- Hole Depths
- Minimum Hole Diameters
- Tread Depths
- Thread Diameters
- Tolerances
- Text and Lettering
Take a look at Geomiq’s CNC Machining Design Guide if you need a hand.
What Factors Need to be Considered When Choosing a Metal for CNC Machining?
Choosing the suitable metal for your part is a balancing act between machinability, intended use, and overall cost. As we have discussed, there are many when designing your part for CNC manufacture, different metals can be machined on a CNC machine, and some metals are more accessible to devise than others. However, when choosing a suitable metal, it is important to consider other factors, such as the design specification of the part and its environmental use.
CNC Machining Time
If your aim is to produce a high quantity of parts at a low cost, this is an essential factor. If a metal has high machinability, such as aluminium, it will take less time to machine and therefore reduce machining cost. It will also allow for more parts to be machined in a given time.
Aside from the machinability of the metal, the complexity of parts will also influence the time it takes to manufacture a factor – the more a CNC machine has to do, the longer it will take and the more it will cost.
Strength and Environment Requirements for the CNC Machined Part
The designed use of the part is a hugely important factor that will heavily influence your choice of metal. For example, if your part will be subject to heavy loading and stresses, you might consider a steel alloy over copper. Similarly, if you want your part to have similar strength properties to steel, but its intended use is in an aircraft, where weight saving is essential, you might consider titanium.
The operational environment will also need to be considered when choosing your metal to consider factors such as corrosion and temperature. For example, you may want to use magnesium for its strength and low weight, but you might want to reconsider that choice if it operates in a high temperature environment.
Finishes and Post-Processing for CNC Machined Metals
Metals with low machinability require finishing or post-processing to remove tooling marks and burs from the CNC machining process. This can significantly drive up costs. If a high-quality finish is required on the part, this can also increase machining cost as it takes longer to manufacture the part. Choosing a metal that can be used as-machined can help reduce costs.
Summary
CNC machines are a good choice for machining metals. The wide range of metals and alloys have many different properties that influence their application and machinability, influencing the overall cost of a part. Make sure you carefully consider the metal you are using for your part and if you need help, check out our online CNC machining service.
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