Induction hardening is a type of surface hardening in which a metal part is induction-heated and then quenched. The metal thus undergoes a martensitic transformation, increasing the hardness and brittleness of the part. In many instances, induction hardening is used to improve a metal component’s properties against intensive mechanical loads and wear. However, there are frustrating limitations in conventional inductors when it comes to performance, quality, set-up costs and operation time. Leading metallurgy company GKN is tackling all these issues through additive manufacturing.
The company is highlighting ways to benefit from inductor coils with an extended lifespan by switching to 3D printing. According to GKN, AM is driving a revolution in the world of induction hardening: manufacturers can take advantage of metal additive manufacturing (AM), offering superior parts and robust production of highly complex geometries.
Additively manufactured copper inductors can guarantee re-producible hardening results, which is quite a unique advantage since – in general – reproducibility is a limit of AM vs traditional technologies. In this case, however, the AM coils are more reproducible than traditional ones, since the AM process effectively includes the thermal treatment phase. They also guarantee a 3 to 4 times longer service life, with shorter set-up time of the hardening equipment and cell. Overall this translates to a reduction in operation and investment costs due to better machine utilization.
A well-kept secret
Like many other segments where AM can already offer clear advantages, the market for 3D printed copper inductors is still slumbering. According to GKN, end-users have yet to notice how much more efficient printed inductors are. GKN predicts that it will take another year before the industry understands this advantage. In a market like induction hardening, users aren’t eager to blindly trust that the first 3D printed inductors will work as needed. A common thought is: “But my application is particularly complex, I’m sure that won’t work!”
In 3D printed coils – like in many other AM segments – users will have to intensively test and experience 3D printing first, and that will take time. A library of successful cases needs to be built up and – perhaps even more importantly – effectively communicated to all potential adopters – even beyond traditional coils manufacturers. Once users gain confidence and realize that 3D printing delivers reproducible results, GKNbelieves that nothing will ever be the same.
Taking the next step
GKN is welcoming questions from clients and prospective clients who are using an inductor with a soldered geometry that is often causing troubles due to subassembly issues. Others who may benefit from AM are those who may have had to compromise on the part geometry due to limitations in the manual manufacturing method.
Understanding whether a part is printable depends on the geometry: if the geometries do not require any or just minor design modification, it can be printed and used right away. If the cooling channel structure must be adapted to the additive production, GKN can offer support in re-designing for a more efficient geometry.
Some categories that may warrant switching to 3D printing as a manufacturing method include inductors with several loops and complex component shapes; inductors where conventional methods cause continuous problems and inductors where several soldering agents were used for soldering.
There is no doubt that the flexibility in design and the guaranteed double lifetime will make induction coils valuable for the hardening process. The results so far have been outstanding and are proven in a real serial production environment.