The material used is a decisive factor for the wear resistance of cutting, punching and forming tools. This is because 3D-printed cutting elements can be optimized with regard to their substrate in such a way that much longer service lives are possible.
Axel Wittig, founder and managing director of Webo, is certain: “If someone had told me in 2016 that the use of high-strength 3D-printed materials in punching and forming tools would be so successful, I probably wouldn’t have believed it.”
The initial plan was to use 3D printing for support components within the tool structure. The focus here was on components with lubrication channels, weight-optimized and movable units, and complex 3D shapes of limited size.
At Webo, they chose powder bed-based laser melting (LPBF) as their manufacturing process and immediately invested in their own metal 3D printers.
From prototype construction to small series and special solutions, it was shown that 3D printing can also be used successfully for active components. The main focus of Webo's developments was now the service life, as classic 3D printing materials such as 1.2709 had proven to be inadequate.
3D printing for special alloys
Webo's willingness to experiment led to standard powders being mixed with specially coated carbide and nitride powders to achieve improved material properties with regard to the service life of components. This was the birth of MMCs (Metal Matrix Composites) produced using additive manufacturing processes. Due to the high potential, a separate company to manufacture the MMCs, Kolibri Metals GmbH, was founded in 2018. Webo was initially Kolibri's largest customer, but the breakthrough came when high-speed steels (HSS) with a high carbon content, for example based on 1.33XX, could be printed in series.
In strict accordance with the company's motto: 'Print as little as necessary and as high-strength as possible', most of the printing activities today take place in the area of hybrid printing. Hybrid means that the active layers (cutting or forming layers) made of highly wear-resistant materials are printed onto an existing basic component (substrate).
In the meantime, the production of MMC is no longer limited to various ceramic materials, but MoS2, nickel, iridium, carbon and many other alloy components are added in measured doses. "This would not be so easy to achieve with classic melting or powder metallurgy (e.g. sintering)," says Michael Ackers, Technical Director of Kolibri Metals. "The specific weights of the individual additives would not lead to a homogeneous distribution in the structure in a melt in the steelworks. This is only possible in the additive process."
Hardness and toughness in the optimal ratio
By adding industrial diamond in small quantities, for example, a targeted carburization of the material can be achieved. This means that steels can be used that have a very high carbon content after hardening and can achieve Rockwell hardnesses of over 67 HRC.
In terms of hardness, the material properties of hard metal in its variants cannot be achieved. Kolibri's goal, on the other hand, is a balanced ratio of hardness and toughness with hardnesses between 67 and 71 HRC.
Reconditioning of stamps and dies
The latest developments in hybrid printing for active tool components focus on the selection of a cost-effective, highly millable and weldable base material with high hardness for optimal bonding of the high-strength print.
The topic of sustainability is particularly important here, as Webo's tools can simply be sanded down and reprinted. Hybrid printing therefore stands for sustainability and resource conservation.
Webo has found that satisfied customers' reports regarding service life and reduced maintenance intervals are consistently positive. Customers have even forgotten about the cutting dies manufactured by Webo because they simply do their job.
“The fact that in the end there was talk of a 10-fold longer service life,” says Wittig, “also surprised us positively.”