It is almost completely silent on Wacker's Aceo campus in Burghausen - only a buzzing sound can be heard from a box the size of a photocopier. This humming box is the first industrial 3D printer for silicones developed by Wacker engineers. Since then, it has been transforming clever ideas into something tangible. This is because injection molding and rapid prototyping have been given a new, fast and cost-effective addition for small batch sizes. With different colors and degrees of hardness from 10 to 80 Shore A, many applications can also be covered for other rubber materials. The properties of the 3D-printed molded parts do not differ significantly from injection-molded products and therefore enable near-series prototypes and small batches.

The Aceo technology is based on a holistic system solution consisting of UV-curable silicones, newly developed printing machines, special software and the expertise to design digital models for 3D printing. At the heart of the technology is the drop-on-demand process, which creates homogeneous physical objects from precisely deposited droplets measuring around 0.4 millimetres. Temporary support materials are used for product geometries with cavities or overhangs. Simultaneous printing of several materials also makes it possible to produce molded parts with different colors, hardnesses or functions.

The exceptional properties of silicones, such as the wide range of applications from -55 °C to 180 °C, the high thermal and UV resistance as well as the good chemical resistance to many media, result in countless applications. The 3D printing of silicones is particularly interesting for the rapid availability of functional prototypes such as connectors, small series for prototyping and field testing such as sensors, soft robotics such as grippers, innovative spare part concepts such as seals or functional integration such as heating or damping.

When designing molded parts for 3D printing, the product developer must be aware that certain design rules must be observed as well as the fact that the molded part has different types of surfaces. These restrictions are offset by product geometries that have not yet been possible to depict and are still beyond imagination. The prompt creative use of design possibilities is the real value contribution of additive manufacturing.

Holger Kunz is also aware of this. His clever idea: a silicone cap that so far only exists on a USB stick. This inconspicuous part should be about the size of a thumb, shaped like a cylindrical bag, closed at the top, open at the bottom and hollow on the inside. As unspectacular as it may look, it is the result of years of tinkering, hard work and a great deal of courage. At the beginning of the year, the mechanical engineer and his team founded the start-up company Formhand around their idea. "It all started seven years ago - quite traditionally over a beer," reports Holger Kunz. "That evening, I told my co-founder Christian Löchte about the as yet unsolved problem of developing a robotic gripper that could grip very thin fabric. At first we joked around, but that's when the idea for Formhand was born."