Weiss Kunststoffverarbeitung: IML control unit made of flame-retardant polycarbonate for modular battery system

Weiss Kunststoffverarbeitung manufactures a control unit using the in-mould labelling (IML) process for the new “BOS battery S” from BOS Balance of Storage AG. According to information released by the company ahead of Fakuma 2026, the component consists of transparent, flame-retardant polycarbonate and a functional film that is back-moulded with the plastic. In addition to processing the material appropriately, matching the appearance of the control unit to the matt surface of the battery housing placed particularly high demands on mould, process and surface technology.

BOS Balance of Storage AG develops lithium iron phosphate battery systems for stationary and mobile applications. The modular “BOS battery S” is intended for use in applications including motorhomes and yachts. The battery system has a capacity of 1024 Wh and can be integrated into various applications via different communication standards and protocols. It can also be combined with lead-acid batteries.

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On the front of the battery housing, a control unit manufactured by Weiss serves as the human-machine interface. The black functional film incorporates backlit symbols and membrane switches and is permanently bonded to the plastic substrate by back-moulding.

The component is produced using the in-mould labelling process. The prefabricated film is placed in the injection mould and subsequently back-moulded with polycarbonate during the injection moulding process. This creates a functional and decorative composite component without requiring subsequent assembly of the film.

One of the key challenges was the selection and processing of the polycarbonate. The application uses a crystal-clear, flame-retardant material. Flame-retardant transparent polycarbonates place particularly high demands on process control, as mechanical and thermal properties must be maintained alongside optical criteria such as transparency, surface quality and a reproducible component appearance.

In addition to the material-related requirements, matching the surface finish played a central role. The battery housing is made from a plastic containing recycled material and glass fibres and has a distinctly matt surface. The colour effect, gloss level and surface finish of the IML control unit therefore had to be designed so that the front panel blends visually into the housing design.

Several testing and optimisation stages were carried out during component development. Weiss adapted material, mould and process parameters to combine the requirements for functionality, surface quality and reproducible series production. Development was carried out in close cooperation with BOS through to series-production readiness.

For Weiss, the project expands its existing range of applications for plastic components used in electrical and electronic systems. The company manufactures housings and components for applications including charging connectors, sensors and radio modules. The IML control unit for the battery system adds an application that combines injection moulding technology, film integration, flame retardancy and stringent requirements for the visible surface in a single component.

Fakuma 2026, Friedrichshafen, Germany,
12–16 October 2026, Hall A5, Stand 5212

More information: www.weiss-kunststoff.de

Weiss Kunststoffverarbeitung GmbH & Co, Illertissen

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