Aluminum is considered one of the best metals for CNC machining because it is relatively easy to machine. Aluminum possesses all the properties required for machinings, such as light-weight, good strength, and perfect durability. Since aluminum is a light metal and easy to machine, you can use it in various applications.
Similar to stainless steel CNC Machining, Aluminum CNC machining process cuts the raw material bit to bit to achieve desired shape to meet the drawing’s specification. So, it is also a custom process like investment casting.
The process is carried out with a CNC (Computerized Numerical Control) machine that produces various three-dimensional objects using CAD (Computer-Aided Design) software to achieve the best and most accurate results.
Benefits of Aluminum CNC Machining
In the market, there are many types of aluminum alloys, which can be processed with casting, forging, extrusion, CNC machining. Here we would like to introduce the benefits of aluminum alloy for CNC machining process.
Easy to Machine
Aluminum is the simplest metal to machine, as it is easy to shape, machine, and process by various methods. Since the metal is soft and easily shatters, it can be quickly machined with machine tools. Moreover, this metal is pocket-friendly and requires less energy compared to steel.
Since aluminum has excellent properties, it offers immense benefits to both the machinist and the customer who orders the part. Aluminum also exhibits exceptional machining qualities that allow for minor deformation during machining. This results in higher accuracy, as CNC machines can achieve higher tolerances.
Good Corrosion Resistance
Aluminum exhibits high scratch and corrosion resistance, even under maritime and extreme atmospheric conditions. We can further improve these properties by anodizing the metal. Please note that corrosion resistance is not the same for all types of aluminum. The metal that is most often CNC machined has a higher resistance.
Perfect Strength-to-weight ratio
The density of aluminum is one-third of steel, giving it a slightly lighter weight than steel. Even being a lightweight metal, aluminum shows high strength. This fantastic lightweight and strength combination is known as the strength-to-weight ratio of metals. Due to aluminum’s high strength-to-weight ratio, it is preferred in many industries, including the automotive and aerospace industries.
Good Electrical conductivity
At room temperature, pure aluminum has an electrical conductivity of around 37.7 million Siemens per meter. However, aluminum alloys have relatively lower conductivity than pure aluminum, but they still provide good results in the production of various parts. Sometimes the electrical conductivity of aluminum does not match the output of the desired workpiece, so it is considered unsuitable material.
Aluminum is highly recyclable due to the subtractive manufacturing process. In CNC machining, we can produce ample chips as waste material. Since aluminum is recyclable, it requires little energy, less effort, and affordable recycling costs. This characteristic of aluminum makes it an ideal material when the budget is low, and the focus is on low material wastage. It also makes aluminum an environmentally friendly material for machinery.
Aluminum Alloys in CNC Machining
To help to decide a suitable aluminum alloy, it is necessary to understand the main features of each aluminum alloy in CNC machining.
Aluminum 2024: This aluminum series has high hardness and contains higher copper content of about 3-5%. The aluminum 2024 series is widely used in the aerospace industry, while no conventional industry prefers to use it at present.
Aluminum 5052: Its main properties include low density, high tensile strength, and high elongation. This series is best suited for producing parts that require relatively strong bending and welding, as they can be easily drawn or formed into complicated shapes.
Aluminum 6061: The primary component of aluminum 6061 is magnesium and silicon, so it carries the advantages of aluminum 4000 and 5000 series. 6061 is successful in industries where high corrosion and oxidation resistance are required. 6061 offers good usability, easy coating, and workability, making it the preferred aluminum alloy for CNC machining.
Aluminum 6063: This series is also known as an architectural alloy. Aluminum 6063 is suitable for producing industrial structural parts of all kinds with high strength and corrosion resistance. These are more common in trucks, high-rise buildings, ships, streetcars, rail vehicles, furniture, machine parts, precision tooling, electronic parts and precision instruments, SMT, PC board soldering, tin carrier electronics, etc.
Aluminum 7075: This is the newest series called “super-hard aluminum.” It is one of the highest-strength aluminum alloys. This aluminum alloy exhibits outstanding mechanical properties and anodizing but is unsuitable for welding and has limited corrosion resistance. They are preferred for the manufacture of highly stressed parts. They are mainly used in aerospace, machining tools, mechanical devices, and fixtures, especially manufacturing.
Steel vs. Aluminum for CNC Machining
Both aluminum and steel are widely used metals in CNC machining. Therefore, choosing the right one for a specific application will be challenging. However, you can consider the following five factors:
- Cost: If your budget is low, consider mild steels and carbon steels, as they are less expensive than the equivalent aluminum alloys. However, stainless steel is even more expensive. Although you can choose the metal based on your needs, prices are not always the same and can vary based on some factors, such as raw material cost, labour cost, shipping cost, etc. When considering the cost, it is also essential to consider the durability of the material because what saves you money in the short term may cost you more in the long term.
- Corrosion resistance: Aluminum and stainless steel offer high rust and corrosion resistance, but stainless steel is more expensive. So, if you require a CNC machined metal with good corrosion resistance while lower cost, aluminum is the right alloy to consider. While the corrosion resistance of carbon steel and mild steel is not good, they has to be post treated after machining.
- Weight: Aluminum weights only around one third of Therefore, companies always perfer to achieve the same or better product performance with a lighter material. This “lightweighting” has become a trend, and many manufacturers are replacing parts previously made of steel with aluminum, such as automotive parts.
- Strength: Althought aluminum is lighter, steel has better strength over aluminum, and is also more durable. So, if the weight is not necessary to consider, steel is more ideal.
- Machining efficiency: Since aluminum is lighter, it can be CNC machinedthree to four times faster than steel. Also, aluminum takes less time to cool than steel; this significantly reduces the machining time of a part (cycle time), and the amount of coolant required.
Compared to steel, aluminum is lightweight and therefore requires less cutting force. This helps cutting tools stay sharp longer. It is also possible to machine aluminum on smaller and more cost-effective machines.
Aluminum CNC Machining Processes
There are several CNC machining methods available for machining aluminum parts. Some of the standard and pocket-friendly ways are as follows.
CNC turning is when the single-point cutting tool remains stationary while the workpiece rotates. The machine determines whether the workpiece or the cutting tool will make a feed motion against each other to achieve material removal.
This is the most commonly used method for machining aluminum parts. Unlike CNC turning, in this process, the multi-point cutting tool rotates about its axis while the workpiece remains stationary about its axis. Material removal and cutting are accomplished by the feed motion of the workpiece or the cutting tool. Sometimes a combination of both is used. This motion can be performed in multiple axes.
As the name implies, this is a simple process for making a hole in a workpiece. In this process, a rotating multipoint cutting tool of the desired size moves in a straight line perpendicular to the surface that requires drilling, eventually resulting in a hole.
Surface Finishes of CNC Machined Aluminum Parts
Once you are done with the machining, you can now perform various surface finish ways to improve the part’s physical, mechanical, and aesthetic properties. Some of the surface finishes are listed below.
Bead & Sand Blasting
This process is performed for aesthetic purposes. In this process, the machined part is blasted with tiny glass beads using a compressed air gun under high pressure. This removes the excess material and creates a smooth surface that gives the aluminum CNC machined parts a satin or matte finish. Apart from bead blasting, sandblasting is also used, in which the excess material is removed with a high-pressure sand stream.
Also, polishing and painting are also used as finishing methods if required.
In anodizing, the CNC machined aluminum part is exposed to a dilute sulfuric acid solution, with an electrical voltage applied between the cathode and anode. It is, therefore, an electrochemical process. Once the electrical voltage is applied, the exposed surfaces of the part are anodized to form a hard, electrically non-reactive aluminum oxide layer. The solution concentration, anodizing time, and electrical current determine the thickness and density. Anodizing can also be used to color a part.
In this process, the part is coated with color polymer powder using an electrostatic spray gun. After the process is complete, the part is cured at 200 °C. Powder coating helps improve strength and resistance to wear, corrosion and impact.
Tips on Aluminum CNC Machining
During CNC machining, the workpiece can become too hot, causing the high coefficient of thermal expansion of aluminum that may affect tolerances. This occurs especially when machining thin parts. Aluminum CNC machine shops can create toolpaths that are not confined to one area for long periods to prevent adverse effects and avoid concentration. This way, the heat diffuses, and you can review and modify the toolpaths in your CAM software that you use to create the CNC machining program.
Applying high forces to some soft aluminum alloys promotes deformation during machining. Therefore, always follow your particular grade’s recommended feeds and speeds to generate the correct forces during machining. To avoid deformation during machining, the thickness of your workpiece should exceed 0.020 inches in all areas.
Since aluminum is malleable, a built-up edge can occur on the cutting tool. This covers the tool’s sharp cutting surface, making it look dull and affecting cutting efficiency. This built-up edge will also result in a poor surface finish on your workpiece. Using carbide instead of HSS (high-speed steel) can help you avoid the build-up. You can also try adjusting the amount and type of cutting fluid for better results.
Aluminum CNC Machine Shop in China
As one of the top leading CNC Machine shops in China, CFS Machinery offers you professional aluminum CNC Machining services to meet your drawing’s specification. At CFS, you will work together with qualified and dedicated staff to produce your custom CNC machined aluminum parts with our CNC machining services at a competitive price We also offer fast delivery and high precision.
Our aluminum CNC machining service includes CNC milling, CNC turning, cnc drilling, EDM, plus various surface finishing ways, to make any custom design parts with high-precision dimensions.
Since we combine aluminum CNC machining with other processes, we stand out from all other CNC machine shops. Our combination processes include:
- Investment Casting + CNC Machining
- Die Casting + CNC Machining
- Extrusion + CNC Machining
- Forging + CNC Machining
- Billets CNC Machining
With customers all over the world, our team can help to manage their workflow and custom parts more efficiently. We have a great team of experienced engineers at CFS machinery who reduce costs by eliminating time-consuming manual tasks. We’ve also automated repetitive tasks, which helps improve profit margins and save lead time for our valuable customers.
If you are looking for a reliable CNC machining company for your aluminum machining project, look no more as you can count on us for better results. For more details, please feel free to contact us!