What is steel powder?
Steel powder is – as the name suggests – steel that has been turned into powder. It has been around since the 1920s, although it really started to gain momentum after World War II. Initially used to make engines through press and sintering, steel powder became a hot topic in the last decade as 3D printing, or additive manufacturing, started to take off.
TRIWA´s watch case is made using a method called Metal Injection Moulding (MIM). In MIM, fine metal powder is blended with a binder material to make what is known as a feedstock, which is then shaped and solidified through injection molding. This allows complex, high-volume parts to be shaped in one step.
“We worked closely with TRIWA to produce a fossil-free steel powder to suit the MIM method,” says Fredrik Mikaelsson, Product Manager Powder at SSAB Special Steel. “The powder is even finer in terms of its particle size distribution than the steel powder we normally make.”
The major advantage of additive manufacturing is that it is more resource efficient, using a smaller amount of material than other methods and producing significantly less waste. It also makes it possible to create a lighter end-product that is more energy efficient.
As for the particle size distribution (PSD), this is important because it needs to be carefully adapted to the type of manufacturing process. The right PSD results in better process stability, which in turn, leads to enhanced quality and yield.
As Fredrik Mikaelsson explains, an additive manufacturing process like MIM or 3D printing places strict demands on the characteristics of the powder: “For example, we have very specific requirements when it comes to roundness, particle size distribution, to make sure the powder is adapted to the demands of each individual process and the unique properties of the application.”
How was the sustainable watch made?
Ludvig Scheja, Creative Director at TRIWA, explains that, once the design was set, a metal injection mold was made, into which the fossil-free steel powder was inserted and formed under tremendous pressure. The watch was then assembled with its dial, crown, movement and hands.
Going forward, TRIWA hopes to be able to incorporate fossil-free steel into more parts.
“Since steel is the most commonly used material in the industry and also the heaviest part of the product, this could be a game-changer,” says Scheja, adding that, given his company’s aim to be carbon neutral before 2026, it still needs a way to make the core fossil free.
“That’s when we’ll show the rest of the industry it’s possible,” he adds.
Fossil-free steel powder even more sustainable
“Steel powder already supports more sustainable manufacturing, because we use less of it and produce a lighter product that, in turn, uses less energy,” says Mikaelsson, who explains that when it comes to making small, complex parts, a large section of metal is typically worked down into a smaller piece. It is therefore not unusual for up to 50 to 75 percent of the original metal to be lost as waste during traditional manufacturing. This is not the case in additive manufacturing, where only the metal needed for the powder is used.
“Once we add fossil-free steel to a process that is already so much more resource efficient, we can really start talking about significant environmental gains,” he adds.
