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The increasing demand for UV coatings on three-dimensional (3D) objects, e.g., in the area of
plastic and metal parts for the automotive industry, represents a new challenge. In conventional
applications, e.g., in the wood or printing industry, the parts are mostly two-dimensional and flat.
Such parts can easily be cured nowadays by radiation cunrig.
Three-dimensional parts with their asymmetries, undercuts, and impressions are in conflict with the required controlled and reproducible conditions of a homogeneous irradiation. Especially for highly scratch-resistant coatings, e.g., on automotive headlight lenses, there are rather narrow process windows with respect to the required UV irradiance and dose.
Thus, in poorly adjusted UV installations either incomplete curing or over-curing may result.
Moreover, the target throughput of parts may only be achieved by using an unnecessarily high
number of UV lamps. An insufficiently cured coating is critical not only for functional reasons but
also for its volatile components which may be hazardous to health.
Until now there was a lack of flexible UV pilot plants for research and development and for
near-production testing of this technology for 3D objects. To provide for this demand, the
Fraunhofer IPA in collaboration with Fusion UV Systems has built a large-scale UV test plant
unique in its kind up to now. Usually the adjustment of UV lamps for 3D applications constitutes a very time-consuming process based on trial and error. In this paper a computer simulation method will be presented by which the distribution of UV irradiance and dose across the surface of a given 3D
