Finding the cure

With ultraviolet-hardened paints becoming increasingly common in the car industry, curing the paint still remains a tricky process that can involve a great deal of trial and error.

In an attempt to address this problem, a team from the Fraunhofer Institute for Manufacturing and Engineering in Stuttgart is using computer simulation to find a way to ensure that the coating is deep, crisp, even — and durable.

Old-style car paints tended to be applied as a liquid spray, with the pigment and film-forming compounds dissolved in an organic solvent. But improvements in coating technology and concerns about the levels of volatile organic compounds in the workplace and environment have led to these substances being replaced with powder coatings.

In these, the pigment is mixed with a polymer matrix and powdered, and it’s this powder which is sprayed on to the car body. It adheres only lightly — often assisted by a static electrical charge on the metal body — and is transformed into the continuous paint film by heating, to melt the individual particles, followed by UV curing.