Aluminum pressing in practice: “The design is crucial”

Aluminum pressing in practice: “The design is crucial”

“Because we already had experience with pressing aluminum for other products, we were able to convince our customer of the advantages. This way, you use the technology of customer A for customer B. The relationship with our customer evolved in the same way: we started with small, separate parts and now we deliver more complex assemblies.”

Hans van Herk is Project Manager at Multifix, he ensures that customers do not have to worry about their production. Hans immerses himself in projects in all possible ways, to do them as good as possible: “For example, by pressing aluminum parts instead of casting.”

What was the problem?

“We received a new order, the customer had made a product that consists of different parts that must be connected to each other. In the past, this connection was made as a steel casting, but that turned out to be too heavy and expensive. We therefore advised to make it from aluminum, but the customer had doubts about the strength of the design: the tensile strength of aluminum is lower by a factor of four. That is why I started looking at other options, together with their design department.”

“I suggested pressing the aluminum to keep it clean and maintain its strength. I investigated this together with one of our suppliers in China, they had already made a similar product for us. You cannot press every shape, so we made the design suitable for this application and offered the project. And production has now started.”

Why should you press aluminum and not cast it?

“When casting aluminum, contamination is a common problem, such as inclusions of unwanted alloy elements. Every pollution is a weakening of the material, and with special / complex shapes you sometimes also get weakening due to the inclusion of air bubbles. In practice, a casting is therefore always weaker than a comparable product, which is made, for example, by pressing. Also, because the molecules enter a ‘fixed’ state with respect to each other due to the deformation, the material is ‘reinforced’. When pressing, you have a pure aluminum alloy that you receive directly from the foundry. You saw off part of it, heat it and press it into a shape.”

“The design must be different in casting than in pressing, you have to adapt your design to the production technique. You should always fill a casting mold as good as possible, so the flow of your aluminum is important. The product must then also be easy to remove from the mold when you open it. Other factors play a role in pressing, you have slightly different ‘draft angles’ and the ‘deformation ratio’ (difference in shape between the base material and the final product) plays an important role.”

Are there any other reasons for pressing aluminum?

“Pressing aluminum is also better for safety. The product we make for this customer is a safety item, which is why the constant material strength is so important. With products like these, the construction must show in time that it is about to break, for example because it first starts to deform and then breaks. This is one of the reasons why we have moved away from cast products, which often break suddenly because they are ‘brittle’ and have a low elongation to break. With pressed products, you can see the material bending before it finally breaks.”

“Our department provides technical support for the production; we are the technical hub. All requests arrive at our desk, we study them for manufacturability and see which supplier suits them best. We then turn it into a Multifix drawing, after which the project goes to purchasing to determine the prices. If the customer agrees with our proposal, we will enter the sample phase and the guidance of production. We test, advise and check and are responsible till the first production run.”

What phase are you now in with the project?

“We are now in the sample phase. Before we go into mass production, we always make a test product first. The customer tests this for mechanical and functional properties and decides whether it can be released for mass production. We then make a ‘0 series’, a small batch that you can use to test the mass production method; the product may be good, but it must also be reproducible. We only do the 0 series if the customer wants to. In this way you do a risk inventory together with the customer.”

“We then take care of the mass production in China, in this case we even deliver everything in service packages that the final technician can use on the fly. And including an RFID label on the packaging, for traceability. The end product is modular, because each location where it is installed is different. With standard parts, the technicians can assemble 80-90% of the end product. The rest is almost always custom work, which the customer carries out himself.”

“I like it at Multifix, I have been here for 12.5 years. At my previous employer, we only made sheet metal, I now have to deal with various production methods such as pressing aluminum. The pleasant thing about Multifix is that there is a lot of variation, the product range is very wide. The fact that I regularly have to travel to China is of course also a welcome change. That keeps it interesting and fun to do!”

More information about aluminum presses? Hans.vanherk@multifix.nl