When working on CNC projects, picking between stainless steel and aluminium is an important choice that can greatly affect how the project turns out.
Even though these two materials have very different properties, they are both strong options for machinists and manufacturers. Stainless steel is known for being strong and resistant to rust. Aluminium, on the other hand, is light and easy to shape.
This blog goes right to the heart of this important decision-making process by breaking down the different qualities of aluminium and stainless steel in the context of CNC projects.
By looking at things like strength, ease of machining, and environmental impact, we hope to provide an in-depth guide that helps choose the best material, ensuring the success and effectiveness of CNC projects in an ever-changing business world.
Stainless Steel CNC vs Aluminum CNC
Aluminium and stainless steel are alike, especially in their appearance and use. These materials are more likely to be used to make things in any business.
It is common for both of these products to be used to make cookware, building tools, healthcare devices, and farm equipment. They are also used in the sports, aviation, and auto fields.
Then, what is the ideal metal for CNC cutting?
You should think about the following things when choosing the right material for your project:
Elemental Composition
The elements that make up a material are very important for CNC machining projects because they greatly affect how hard, strong, durable, and resistant to rust the metal is. At least 10.5% of stainless steel is chromium. Other elements comprising about 0.03% to 1% of stainless steel are aluminium, silicon, sulphur, nickel, selenium, molybdenum, nitrogen, titanium, copper, and niobium.
Because it contains chromium, stainless steel has great qualities when it comes to resistance to heat and corrosion. It is found in silicon, magnesium, zinc, manganese, iron, copper, titanium, chromium, zirconium, and other metals found on resistance.
Stain steel metals’ nickel, chrome, and iron compounds make them more corrosion-resistant. It does this because chromium makes a protective layer that can fix itself. Still, aluminium is very resistant to rust because it has an oxide layer that protects it. This covering protects the metal from rust and other things that break down metal.
Electrical Conductivity
In terms of electrical conductivity, copper is the gold standard. It has a conductivity of 100%. If you compare aluminium to copper, you can see that it conducts electricity 61% better and weighs about 30% less. Regarding how well it moves power, stainless steel is only 3.5% as good as copper.
If conductivity is the most important thing for your CNC machining job, aluminium is the best material. It’s so good at carrying power and high-voltage cables over long distances that it will be your first pick.
Material Hardness
The ability of an object to resist being bent or scratched is called its hardness. The Brinell hardness grade is used to find out how hard something is. It is important to know that the type of metal affects how hard stainless steel is. From 80 to 700 on average, it’s hard.
The toughness level of aluminium is less than 20. This only means that aluminium is easier than stainless steel. So, if your project is mostly about how hard something is, you should choose stainless steel.
Thermal Conductivity
The first thing to consider when making custom heat sink parts or samples is how well they conduct heat. This is why aluminium is often the best material for heaters or air conditioners. Aluminium is a better thermal conductor than stainless steel, with a value of 1460 BTU-in/hr-ft²-°F (210 W/mK).
However, aluminium has a lower melting point and loses its quality when heated above 400 degrees Celsius, melting or softening. Stainless steel also moves heat around well, which makes it better for use when the temperature is high.
Weight
It is thought that aluminium has a density of 2.7 g/cm3 and stainless steel has a density of 8 g/cm3. This means that stainless steel weighs three times as much as the same amount of aluminium. Because of this, aluminium is lighter than stainless steel. It is the best material for the marine, aircraft, and building industries.
Melting Point
For CNC projects, the material’s freezing point is very important. Parts work at high temperatures, and when they melt, they will stop working because they will have changed from solid to liquid. The material is better for die casting or extrusion because it has a lower freezing point.
Different alloying elements make stainless steel’s melting point range from 1230 °C to 1530 °C. Around 660.37 °C is about as low as the melting point of aluminium gets. This means that stainless steel is better than aluminium if heat resistance is the most important for your CNC machining job.
Production Costs
Different alloying elements give stainless steel and aluminium different properties. Many alloying elements give stainless steel different properties, such as martensitic stainless steel, ferritic pure steel, alloy stainless steel, austenitic steel, hammer hardening, and more. Most of the time, stainless steel costs more to CNC machines than aluminium.
Machinability
This refers to how simple it is to use CNC to make a part. No matter what, a CNC machine makes it easier to make samples and parts, whether zinc or aluminium. Aluminium is easier for CNC machines than stainless steel because it is less stiff and softer than stainless steel.
Shear Strength
A material’s shear strength tells you how well it can handle shear loads. Between 74.5 and 597 MPa is the shear strength of stainless steel. Between 85 and 435 MPa is the shear strength of aluminium. Aluminium is less strong than stainless steel when it comes to sheer power.
Weldability
Steel and aluminium are both simple to join together. But it takes a lot of skill to weld aluminium metals. Also, it would help if you were careful not to damage the part.
The function of the Materials
Aluminium is often used in consumer technology projects because it is flexible and has a smooth surface. Countries that make things use this material instead of steel and plastic.
These two things are both used to make things. You will need to know the difference among these materials if you are getting something you will use for a long time, like jewellery. There won’t be a big difference if you’ve never bought something made of cut aluminium or steel.
Aluminium and Stainless Steel Are Good Materials for CNC Machining
Using CNC machines to make parts and products is a popular way to make things. Digital Computer Numerical Controls (CNC) are used to make parts, but it can take time to choose which material to use. The following are some reasons why metal and stainless steel are good for CNC drilling.
Aluminium
Aluminium is a strong metal that is also soft, light, and easy to shape. This makes it great for CNC machining. It can look dull grey based on how rough the surface is, but it is not flammable and is not magnetic.
For simple reasons, metal is easy to work with, which is one of the main reasons engineers choose it for machined parts. This would be more helpful for the worker making the part, but it’s also very helpful for the company that orders the part and the person who will use it.
Different grades of aluminium are very different when it comes to corrosion protection or how well they can handle oxidation and chemical damage. Luckily, some of the most common grades for CNC cutting are also some of the toughest.
Stainless Steel
Stainless steel is a combination of steel; as the name suggests, it is steel that doesn’t rust. It is made up of iron as the base metal, and chromium is added to make it resistant to rust. An alloy is a mix of metals.
Steel that doesn’t rust is called stainless steel. Different types of stainless steel vary in how strong they are and how well they prevent rust. A small amount of carbon is added to make it stronger and tougher, which adds to its properties.
Nickel may also be added to iron to stabilise its crystalline structure. This will make it stronger at all temperatures and help it fight corrosion.
When used in CNC cutting, one of the best things about stainless steel is that it can fix itself afterwards. Chrome covers the iron with a transparent layer to keep air and water from getting to it.
This is done through a process called passivation. If the top gets scratched, the layer quickly grows back when oxygen is present. Because of this, excellent stainless steel will not rust even if it gets scratched while it is being worked on.
How Well Do Aluminium or Stainless Steel Hold Heat?
This is a tough question with a likely answer that changes depending on the situation or use. Regarding heat movement and conduction, aluminium is the winner.
But the point at which aluminium melts is much lower than that of even the softest type of stainless steel. The point of melting of 304 stainless steel is around 1400C (about 2550F), while the melting point of most aluminium metals is around 400C (about 750F).
Stainless steel will probably soften before this point, but it can still handle as much heat as aluminium and three times as much. But stainless steel doesn’t let heat pass through it as well. Because of this, it’s not as good for use where temperatures aren’t as high, but fast heat transfer is needed.
Some examples of possible situations are car radiators, computer heatsinks, or HVAC parts. You need to know about temperature tolerances and standards to choose the right metal. This is because each metal has its unique properties.
Conclusion
For a CNC job, picking between stainless steel and aluminium is very important because it can have a big effect on the end result. Strong and resistant to rust, stainless steel is a good choice. Aluminium, on the other hand, is light and easy to shape. Several things determine what kind of material is best for CNC cutting, such as its weight, melting point, electrical conductivity, hardness, and heat conductivity.
Stainless steel has a protective layer made of chromium that makes it more immune to corrosion. It also conducts electricity better than copper, though it weighs 30% less and is 61% lighter. But it can’t move power as well as copper (3.5%).
Another important thing to think about is how hard the material is. For example, metal is harder than stainless steel. Most people think it’s the best material for heat sink samples or parts because it transfers heat better. It does lose its quality when cooked above 400 degrees Celsius, though, because it has a lower melting point.
Steel is denser than aluminium, at 8 g/cm3, while aluminium is barely 2 g/cm3. It is better for the building, plane, and marine businesses because it is lighter. For CNC projects, the melting point is also very important. Stainless steel has a lower melting point than aluminium.
Stainless steel and aluminium have different production costs because of the different alloying elements that are used and how they behave. Most of the time, CNC tools cost more for stainless steel than for aluminium. Another reason is machinability. Aluminium is easier to work with because it is less stiff and softer.
Another thing to think about is the shear strength. The shear strength of stainless steel is between 74.5 and 597 MPa, and the shear strength of aluminium is between 85 and 435 MPa. Another factor is how easy it is to weld. Steel and aluminium are easy to join, but it takes more skill.
Because it is flexible and has a smooth surface, aluminium is often used in consumer technology projects. It’s also used in the metal business. Stainless steel, which is made up of steel and chromium, doesn’t rust and can be fixed after being worked on. But it doesn’t melt as hot as stainless steel does.
304 stainless steel melts at about 1400C (about 2550F). Stainless steel can handle the same amount of heat as aluminium, but it doesn’t let heat pass through it as well. This means it’s not as good for high temperatures or moving heat quickly.
Picking the right material for CNC machining rests on things like how much it costs to make, how easy it is to machine, how strong it is when sheared, and how well it can be welded.
Content Summary
- Choosing between stainless steel and aluminium is crucial for CNC machining projects.
- Stainless steel is renowned for its strength and corrosion resistance.
- Aluminium is appreciated for its lightweight and ease of machinability.
- This blog aims to guide the selection of materials for successful CNC projects.
- Both materials are popular in various industries, including cookware, healthcare, and automotive.
- Elemental composition significantly affects a material’s suitability for CNC machining.
- Stainless steel contains chromium, enhancing its heat and corrosion resistance.
- Aluminium’s oxide layer provides natural rust resistance.
- Copper sets the standard for electrical conductivity, against which other metals are measured.
- Aluminium’s electrical conductivity is superior to stainless steel’s.
- Material hardness, measured by the Brinell scale, influences CNC machining choice.
- Stainless steel’s hardness varies widely, typically offering more hardness than aluminium.
- Aluminium’s lower hardness makes it easier to machine than stainless steel.
- Thermal conductivity is crucial for applications like heat sinks.
- Aluminium’s superior thermal conductivity makes it ideal for heat transfer applications.
- Aluminium’s lower melting point affects its suitability for high-temperature applications.
- Stainless steel’s higher melting point offers better heat resistance.
- The weight difference between stainless steel and aluminium affects their application suitability.
- Aluminium’s lower density makes it preferable for lightweight applications.
- Production costs for CNC machining vary between stainless steel and aluminium.
- Different alloying elements in stainless steel create a variety of subtypes.
- Stainless steel generally incurs higher CNC machining costs than aluminium.
- Machinability refers to the ease of creating parts using CNC.
- Aluminium’s softer nature makes it more machinable compared to stainless steel.
- Shear strength, indicating a material’s load-bearing capacity, differs between the two metals.
- Stainless steel generally offers higher shear strength than aluminium.
- Weldability is a consideration, with aluminium requiring more skill to weld.
- Aluminium is popular in consumer technology projects due to its flexibility and smooth surface.
- Stainless steel’s rust resistance is one of its key advantages in CNC machining.
- Stainless steel’s self-repairing chromium layer protects against corrosion.
- The choice between aluminium and stainless steel depends on specific project requirements.
- Aluminium’s attributes make it a strong candidate for CNC machining.
- Aluminium’s non-flammability and non-magnetic nature add to its appeal.
- The corrosion resistance of aluminium varies across different grades.
- Stainless steel combines iron with chromium for enhanced rust resistance.
- Adding carbon to stainless steel increases its strength and toughness.
- Nickel may be added to stainless steel to improve temperature resilience and corrosion resistance.
- Stainless steel’s ability to self-heal scratches through passivation is beneficial in CNC machining.
- Deciding between aluminium and stainless steel for heat-related applications depends on specific needs.
- Aluminium excels in heat transfer but has a lower melting point than stainless steel.
- Stainless steel can withstand higher temperatures but is less efficient in heat conduction.
Frequently Asked Questions
In what applications is stainless steel preferred over aluminium in CNC machining?
Stainless steel is often preferred where corrosion resistance, high strength, or specific aesthetic qualities are crucial. Common applications include aerospace components, medical devices, and parts exposed to harsh environments.
How does thermal conductivity impact the CNC machining process for aluminium?
Aluminum has high thermal conductivity, so it dissipates heat quickly during machining. This property can be advantageous, preventing heat buildup and reducing the risk of thermal damage to the workpiece. Machinists need to consider this factor when selecting cutting speeds and feeds.
What surface finishes are achievable with stainless steel and aluminium in CNC machining?
Both stainless steel and aluminium can achieve a variety of surface finishes in CNC machining, ranging from smooth to textured. Stainless steel can be polished to a high lustre, while aluminium can be anodised for improved corrosion resistance and aesthetic appeal.
Are there specific CNC machining techniques for optimising tool life when working with stainless steel?
Optimising tool life in stainless steel machining involves using appropriate cutting speeds, feeds, and coolant strategies. Employing coated or carbide tools designed for high-temperature applications can also enhance tool longevity.
What are the environmental considerations when choosing between stainless steel and aluminium in CNC machining?
Both stainless steel and aluminium are recyclable, but aluminium has a lower environmental impact on energy consumption during production. Additionally, aluminium’s lighter weight can reduce transportation costs and energy usage. These factors align with sustainability goals in material selection for CNC machining projects.
