tech.day 2022: Well on the way to additive silicone manufacturing
“As of the end of this year, we will be able to produce prototypes and small batches in silicone through additive manufacturing”, reports Marcel-Wolfgang Müller, Process Engineer for Additive Manufacturing at Sterner Werkzeug GmbH in Marchtrenk, Austria with evident pleasure. This process technology sees the starlim-sterner Group expanding its process expertise and, once again, provides impressive proof of innovation leadership in the processing of liquid silicone. Additive manufacturing of silicone components means the Group can offer its customers an efficient and flexible production variant without expensive and time-consuming mold construction.
For some considerable time now, additive manufacturing has been firmly established in the processing of thermoplastics for small batches of up to 1,000 items and the production of prototypes. Unfortunately, these production methods cannot be applied to silicone processing. While a thermoplastic is transformed into a plastic state through exposure to heat and, in this condition, can be deposited layer by layer and with great precision into a desired geometric form, silicones have low viscosity and, consequently, cannot be simply manipulated in a layer-based process. sterner has for this reason opted for a process involving silicone additive manufacturing (SAM). For the first time, this method allows 100% pure silicone to be processed to create products without the use of molds. The layer structure is created from top to bottom in this respect, with the cross-linking reaction being induced by light. A model created previously in CAD is projected onto the surface of a tray containing liquid silicone for this purpose with the aid of a projector. The first layer solidifies under the influence of light and, with the aid of a mobile platform, is pressed upwards to the height of the layer before the next layer is exposed beneath it. “We’re currently testing the digital light process here in the company and evaluating the feasibility of the manufacturing process with regard to optimum component properties”, explains Marcel-Wolfgang Müller. In an initial step, models can be created on a building panel measuring 130 x 70 x 100 mm in three colours, namely black, red and blue, and four different Shore hardness levels of A 30, 40, 50 and 60.
As Process Engineer for Additive Manufacturing, Marcel-Wolfgang Müller has been involved for a year now at Sterner Werkzeug GmbH in Marchtrenk in extremely intensive research examining the possibility of using silicone in an additive manufacturing process. In addition to its innovative nature, this technology also represents a further link between the two partner enterprises, sterner and starlim, the liquid silicone processor. This corporate group, which has remained in family hands up until the present, emerged from the union of the mold constructor established in 1974 and starlim, which was founded 10 years later. sterner today manufactures silicone molds exclusively for starlim and, consequently, is jointly responsible for the latter’s success which, with the production of 14 billion silicone components every year for a variety of sectors, is both the market leader and innovation driver in this context.