Höganäs AB is the world’s leading metal powder manufacturer. Both recycled scrap metal and iron ore is used as raw material. Metal powder has developed into a high-tech product, often being used to make components for cars and other applications by pressing and sintering (a heat treatment process fusing the material). An average car contains nine kilograms of powder, and Höganäs controls half of that market.
Pressing and sintering is both cheap and energy efficient in comparison with other methods of forming metal parts – hence the company’s vision, ”make more with less”. Powder metallurgy entails fewer process steps, and can reduce waste of material by 20-30 percent while the energy used in production can be reduced by half.
The company seeks its origin in coal mining and brick manufacturing. From the 1930s onwards, the importance of powder metallurgy has increased steadily. Höganäs today has 1700 employees. The company headquarters are still located in Skåne, while production takes place in eight different countries around the world.
– 99 percent of what we do is powder. But there are a couple of exceptions, businesses still in their infancy. One of these is a new kind of additive manufacturing, says Ralf Carlström, in charge of Höganäs Digital Metal.
Within their subsidiary Digital Metal, launched in 2012, Höganäs is developing their own 3d-printer. Freeform manufacturing has so far mostly been used for industrial prototyping – but Digital Metal is using metal powder to print actual components. They recently doubled their capacity by adding two more printers.
– Our ambition in this context goes beyond selling powder, we will deliver finished products. Here, most of the value lies in the design step and the actual manufacturing. By building layer by layer, any geometry can be obtained, Ralf Carlström explains.
Inkjet technology is used to print the details. A CAD-guided pattern is drawn on a thin layer of metal powder, with a binding agent instead of ink. Another layer is then added on top of the first, and so on until the finished component is tempered and sent to the kiln for sintering.
– We really just started this. In terms of revenue and volume it is still small, and it may not be a large-scale operation for some years. But it is cutting edge, and it is a new domain where we are willing to go further in the value chain.
When the technology can be used, the need for expensive and complex tools is eliminated and less material goes to waste. Another benefit is the ability to create almost arbitrarily complex shapes – something that allows for technically advanced special components and detail work, beyond what other methods possibly could achieve. It also creates opportunities for weight-reduction.
Less weight of course means increased energy efficiency in transport; air traffic is one example where this immediately would translate into environmental advantage. According to IPCC, 3-4 percent of climatic influence is due to air traffic, and emissions are comparable to what they would be if every passenger drove the same distance in their own car. While fuel consumtion and emissions per passenger kilometer are steadily going down – the last 40 years has seen a 70 percent reduction – the sector still sees total emissions rise, as more people travel further and more often. Reducing the weight of airplanes would save fuel, and every kilogram would make a difference. Technologies like Digital Metal’s could conceivably be used to strip down non-critical airplane parts, making them hollow or meshlike.
– It still is more time-consuming than pressing and sintering, though. A part which could be pressed in ten seconds might take hours to print. On the other hand, with 3d printing, limited volume does not drive the cost per component up. I think they are technologies completing each other.
While a break-through in aircraft parts and similar still lies further in the future, Digital Metal already is up and running in niche applications: small, complex metal components, highly specified in tolerance and surface smoothness.
– Our method is especially well suited for industrial manufacturing, medical and design applications, so that is where our aim is today, Ralf Carlström notes.
Article published in February 2015