CNC machining is one of the top manufacturing methods for making parts and prototypes. This is because computer numerical control (CNC) has excellent precision and automation. Moreover, it has other benefits, such as efficiency and speed, that are difficult to achieve with traditional manufacturing techniques.
To make CNC machining successful, you need to choose the right material. As a result, you have to consider several factors, such as cost, corrosion resistance, electrical conductivity, surface finish, and more. The good thing about CNC machining is that it supports a wide variety of materials. Nevertheless, aluminum and stainless steel are the most popular materials used.
Aluminum CNC vs Stainless Steel CNC
Stainless steel and aluminum have a lot of similar features, especially in their applications and look. It is easier to come across products made from these materials in any given industry. Both of these materials widely used in the manufacture of cookware, construction equipment, building tools, medical equipment, and agricultural equipment. In addition, they are used in aviation, automotive, and sports industries.
So, which is the best metal for CNC machining?
To select the right material for your project, you need to examine the following aspects:
Elemental Composition
In any given CNC machining project, you have to pay attention to the elemental composition of the material. This is because it has an impact on corrosion resistance, strength, and hardness. Being an alloy, stainless steel is mainly made of iron and carbon.
Depending on the grade of stainless steel, it can also contain other minerals such as silicon, titanium, chromium, copper, and nickel. Aluminum alloys can also contain minerals such as iron, magnesium, zinc, chromium, and copper.
Corrosion Resistance
Stainless steel alloys that contain nickel, chromium, and iron minerals have improved corrosion resistance. That is because chromium creates a protective layer, which has self-healing capabilities. Nevertheless, aluminum has great corrosion resistance because of its protective oxide layer. This coating prevents the metal from rust and corrosion agents.
Electrical Conductivity
The conductivity of a metal is measured against copper, with copper given 100% conductivity. Based on this, pure aluminum has 61% conductivity, but it is lighter than copper. On the other hand, stainless steel boasts less than 5% conductivity. Therefore, if electrical conductivity is the main aspect of your CNC project, then you should go for aluminum.
Material Hardness
Hardness can be defined as the ability of a material to withstand deformation or etching. Brinell hardness rating is used to measure material hardness. You should note that the hardness of stainless steel varies depending on the alloy type. The average hardness varies from 80 to 700. Aluminum has a hardness rating of less than 20. This simply means stainless steel is harder than aluminum. Therefore, if hardness is the core consideration for your project, then you should go for stainless steel.
Thermal Conductivity
When you compare these two metals, aluminum has better thermal conductivity. However, since aluminum melts at 400 degrees Celsius, it loses these properties. On the other hand, stainless steel is thermally conductive. This explains why it is suitable for projects that are subjected to high temperatures.
Weight
The density of aluminum is estimated to be 2.7 g/cm3 and that is stainless steel is 8.0 g/cm3. This means that the same volume of aluminum is a third weight of stainless steel. As a result, aluminum is lighter as compared to stainless steel. This explains why it is the preferred material for construction, aircraft, and marine industries.
Durability
Aluminum and stainless steel are durable metals. However, stainless steel, being stronger and harder than aluminum it, has better durability. That explains why it is used in the manufacture of automotive parts. if durability is the main aspect of your project, then go for stainless steel.
Machinability
This refers to how easily a part can be made through CNC machining. In any case, it is easier to make parts and prototypes with CNC machine whether they are made of aluminum or stainless steel. Since aluminum is less rigid and softer as compared to stainless steel, it is easier for CNC machining than stainless steel.
Weldability
Both aluminum and stainless steel are easy to weld. However, welding aluminum alloys requires a lot of expertise. Also, care is needed to avoid damaging the part.
Tensile Strength
Aluminum has lower tensile strength than stainless steel. However, some aluminum alloys have higher tensile strength. If tensile strength is the point of focus for your CNC project, then select stainless steel.
Cost
Aluminum and stainless steel have a range of properties and are available in different types. This means they are available at a range of prices. Nevertheless, the cost of CNC machining stainless steel is higher than that of aluminum. However, the cost of stainless steel is lower than aluminum but varies depending on the type and grade.