Automated application of PU gaskets on components

The benefits of foam gaskets compared to manually inserted seals

PU gaskets are used in door modules and lighting in the automotive industry, in door seals and ventilation systems for switch cabinets, and in the filtration and packaging industry, for example. They are applied via the FIPFG (formed-in-place foam gasket) process. The foam gasket is applied ‘in situ’ – the dual-component material is applied directly to the component where the seal is needed. The seal then hardens at room temperature. This is why it is sometimes referred to as an in-situ seal. 

With FIPFG, polymeric reaction materials are metered, mixed and then applied using a dynamic mixing system such as dynamicLine from DOPAG. This involves an A-component (polyol) and a B-component, the hardener (MDI isocyanate). The A-component has molecule chains of different lengths. This determines how soft or hard the foam is after hardening. The longer the molecule chains, the softer and more flexible the foam. Mixing the A and B-components in the mixing system starts the reaction. The molecule chains connect with one another and a polymer is formed. This produces carbon dioxide as a fission product. With the technology used by DOPAG, the low-pressure process, this is responsible for foaming the material. For example, it can be applied directly into the groove or mould as well as onto flat surfaces with the aid of a linear robot. This produces a soft foam gasket that hardens at room temperature without the use of a tempering oven.

What are the benefits of PU gaskets compared to manually inserted seals?

  • In principle, all industrial components (also 3D) and shapes can be sealed
  • PU gaskets can be automatically fixed in position; they can stick without additional adhesive tape
  • The start and end points of the foam bead merge into one another thanks to the controlled overlap programmed by DOPAG, with no undesirable coupling points
  • No open joints or notches
  • Parameters such as the width, height and hardness of the gasket can be influenced
  • Reduced possibility of error compared to manual application
  • High cost-effectiveness: compared to manually inserted gaskets, the costs for the gasket are lower considering the high quality
  • Short cycle times enable efficient, automated production
  • Low storage requirements 
  • Sustainable: there is practically no waste compared to punched or cut gaskets
  • Environmentally friendly rinsing of the system using water
  • Non-sticky at room temperature after around 4 to 20 minutes, so oven hardening is not required

dynamicLine – an efficient system for the production of PU gasketing

DynamicLine from DOPAG was specially developed for gasketing/FIPFG. Its dynamic mixing system processes polymeric reaction materials for the production of PU gaskets precisely and with consistently high quality. With the use of a linear robot, the gaskets can be applied directly onto the component automatically. It is also possible to position the component beneath the permanently installed mixing head with the aid of an industrial robot and start with the geometry of the foam bead. The gasket then hardens at room temperature. The time required depends on various factors, including the material, mixing ratio, room temperature and air humidity. The control unit can store various metering and positioning programmes. This enables various parameters to be changed flexibly. For example, different components or material formulas can be selected, or different discharge capacities with different gasket widths or heights.

Dynamic Mixing System for Gasketing/FIPFG