Replacing metal car parts, such as bumpers, with plastic gives automotive manufacturers significant benefits in fuel economy, reduced manufacturing costs, and increased opportunities for recycling, but getting such components to form a strong adhesive bond to the frame of a vehicle has been a major challenge. Now a collaborative research team led by the University of Warwick's Warwick Manufacturing Group have found a simple plasma pre treatment process that solves that problem.
Until now one of the most effective ways of solving this problem has been to use "friction welding" but that process can leave unacceptable amounts of unsightly "weld swarf" marks which are difficult and expensive to eliminate from the surface of plastic components. The research team considered a number of other processes that might prove more acceptable and finally hit upon a plasma treatment that was being already being used in the US to apply paints and labels to plastic products.
Rebecca Cain, a research fellow with the University of Warwick's Warwick Manufacturing Group, worked together with Hamilton machinery sales Ltd (who supplied the Lectro machinery used in this "forced air plasma surface treatment"), adhesive suppliers Gurit-Essex now Dow Automotive, polymer supplier Solvay Engineered Polymers, car component manufacturer Linpac Automotive, and Bristol University. In an example of successful collaboration between universities and industry they developed a process that allowed large plastic components to be easily applied to automotive bodies.
They devised a simple method which fixed a plasma spraying tool to a robot arm. This was used to rapidly treat / oxidise the mating surfaces of plastic car components. The actual mechanism is complex, but essentially it deposits oxygen based "hand holds" onto the surfaces. These handholds greatly increase the performance of the adhesives used to bond the components. The bonds created by adhesives used on the surfaces treated with this technique have passed all the standard automotive impact tests.
A further advantage is that once treated by the plasma the component stays treated for up to a month allowing significant flexibility in the manufacturing process.
The research is supported by the Foresight Vehicle LINK programme.
For further details please contact:
Rebecca Cain, Warwick Manufacturing Group,
University of Warwick
Tel: 024 76 528314
Dr Gordon Smith Warwick Manufacturing Group,
University of Warwick
Tel: 024 76 523784