What are the 5 ways to fabricate aluminum parts?

Aluminum is a widely used material to produce mechanical parts. Because it is easy to process, it’s light and it is a strong metal. In addition, there are different methods to apply a surface finish to protect aluminum parts from corroding and to give it a beautiful look. Because we use aluminum in a broad range of applications, there are 5 different ways to fabricate aluminum parts: aluminum CNC machining, aluminum extrusion, sheet metal, aluminum casting and forging of aluminum. Some of the manufacturing processes are intended to reduce de overall cost, focusing on using less raw material to start with. Below we go through these 5 ways of aluminum parts manufacturing and production of half fabricates.

  1. Aluminum machining from a full block or bar.
  2. Aluminum extrusion has great advantages.
  3. Sheet metal is an alternative fabrication process.
  4. Molding and casting of aluminum.
  5. We forge aluminum to reduce scrap material.

1. Aluminum CNC machining from a full block or bar.

With CNC machining we mean milling and lathing. CNC machining is the most straight forward way of processing aluminum. We mount a block of aluminum to a milling machine. Or, we clamp a bar in a turning machine, in order to process it with a cutting tool. The principle of both ways is to cut chips of metal with a cutting tool in order to obtain the desired shape of the product. In case of a milling machine, it is the the cutting tool that rotates. Where as with a turning machine it is the product that rotates.

Aluminum CNC machining.

Aluminum cnc machining is a general term those manufacturing processes removing material with a machine controlled by a computer. Milling, turning and wire cutting are among these production techniques. When milling, the workpiece is fixed on the machine table and the cutting tool, also called a “mill”, spins. Whereas for turning the part rotates and the cutting tool moves along at least 2 axis.  For Machining of aluminum parts allows fast cutting speeds. Also, when there is good liquid cooling, we obtain a nice finish of the part. However, there is often a difference in surface roughness depending on the feed direction compared to the rotation direction of the tool. Did you know that alcohol is a very good cooling agent to cut aluminum milling parts? It makes the processed surfaces of aluminum CNC machining parts shiny.

The advantage is that almost any shape can be machined. However, we need to turn and clamp the part to process each side, unless we use a 5-axis CNC machine. And there is a lot of scrap, which has an impact on the unit cost.

Usually, CNC milling and turning can be done with tolerances of +/-0.05mm. This kind of accuracy is already very good for production of most metal parts. In case a parts needs more accurate features we can use additional machining process such as reaming and sometimes grinding.

Aluminum cnc machining includes milling of a customized aluminum enclosure for electronics

2. Aluminum extrusion has great advantages.

Extrusion is a manufacturing process used to make half fabricates.  To clarify, we heat a bar of aluminum to the deforming temperature. Next, a piece of about 500 millimeter long is cut-off. Then, the operator puts this piece into the feeder of the extrusion machine. At the end, we press the aluminum with high force through an extrusion mold made of hardened steel. The result is a long piece of extruded aluminum with the desired section of the product. Those pieces are usually 12 meters long. After aluminum extrusion, the strips are pulled to make the straight. Now, we cut the long pieces to the desired length of the final product. That is how we get extruded aluminum parts. In most cases the product still needs to be machined.

The advantage of extruded aluminum parts is that there is a large reduction of scrap material in order to obtain the final part. However, the section of the product is fixed and the number of integrated features is limited.

Nicely finished black anodized aluminum extruded housing for electronics

3. Aluminum sheet metal is an alternative production process.

Sheet metal processing is a different way of 5 ways to manufacture aluminum parts. We start from a thin sheet of aluminum. Next, we cut the aluminum sheet into the correct shape. Therefore, we use laser cutting machines and punching machines. There are flat sheet metal parts and bended products. Bending of the aluminum sheets happens with a bending machine but also with punching machines and presses.

Aluminum sheet metal is an alternative fabrication process.

4. Aluminum molding and casting.

There are different ways of molding aluminum parts.

Injection molded aluminum parts.

We do injection molding of aluminum as well. This is a process where liquid aluminum is injected under high pressure into an injection mold. As a result, we get parts with almost all desired features present after they come out of the mold. This technique is only suitable for production of large quantities, because the injection mold is relatively expensive. We can produce molded aluminum parts with wall thickness of 1.2mm.

Sand casting of aluminum parts.

The mold cost is a lot cheaper with sand casting but you have to accept the rougher shape and surface of the products. Sand casted parts have bigger tolerances and the material is more brittle because of the casting under low pressure. In most cases, the casted aluminum parts still need machining of certain features. For instance, we process cavities with narrow tolerances with our CNC machines. Also, we drill and tap threaded holes after molding. Casted aluminum parts are not suitable for anodizing because of the material structure. Therefore, they are usually powder coated.

Casted aluminum enclosure IP65 256x200x80

5. We forge aluminum to reduce scrap material.

And finally, among the 5 ways to fabricate aluminum parts is forging of aluminum parts. This is another way to reduce waste. We literally press a block of aluminum between a positive and negative side of a hardened steel mold. Therefore, our factory uses a large press with a pressure of 5000 tons. As a result, we obtain a perfectly shaped part. Just like with the injection molding process, we machine burrs, holes and threaded holes afterwards to obtain a more accurate product. Aluminum products processed with a press are suitable for anodizing because the structure is similar to extruded aluminum.

This manufacturing process for aluminum parts starts to be viable at production runs above 3000 pieces.

Large metal press

It is important to offer different ways of  manufacturing, in order to fabricate a broad range of aluminum components. I hope you learned a bit more about the 5 ways to fabricate aluminum parts.

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