Partners in rear view perfection
by Jon Brooks
Working in an exciting partnership, researchers from the University of South Australia and the multinational component manufacturer, Visiocorp Pty Ltd, are about to crack
an engineering challenge with the creation of a robust one-piece plastic wing mirror for the automotive market.
The new mirror is set to replace traditional component glass units that require a series of complex parts, including heater pads, actuators and brackets to perform the same job.
The new one-piece design relies on advanced surface coating technology, developed by the team at UniSA, to achieve a range of vital factors - a scratch resistant coating to protect the polycarbonate mirror substrate, a heater layer to de-ice the mirror in the cold, highly reflective and environmentally stable mirror coatings, and thin film hydrophobic coatings to improve water shedding properties.
Research and development for the product is a collaborative effort from a team of researchers at UniSA’s Mawson Institute and The Wark™, and product designers and developers at Visiocorp, in partnership with the Cooperative Research Centre for Advanced Automotive Technology.
UniSA research team member, Colin Hall, says the project is a real example of how R&D can bring concepts to life.
"In engineering terms, we’re talking about some very exciting technology," Hall said.
"What we’re working to develop with Visiocorp is a one piece plastic unit which goes through a series of coating processes to apply the reflective mirror surface, the metallic heater element on the rear for the American and European markets, and a final abrasion resistant coating on the outside.
"The end result will be a shatter-proof, scratch-resistant, heated mirror which is lighter, cheaper and potentially much more environmentally friendly in terms of its manufacture."
Over the past 10 years, project partner Visiocorp has perfected the production of injection-moulded, strain free plastic mirror bases, which reach UniSA as clear plastic panels.
The team at UniSA - including Dr Peter Murphy, Colin Hall, Kamil Zuber and Professors Rob Short and Hans Griesser - embarked on a mission to perfect plasma polymerisation and vacuum sputter coating of the mirrors.
"Coating of plastics is not new - dip coating has been widely used for the past 30 or so years particularly in the ophthalmic sector," Dr Murphy said. "But other industry sectors seem to have been slow to pick up on this technology. Our contribution will be to perfect the thin film coating processes required to get the product into the marketplace.
"Using a vacuum chamber that employs both sputter coating and plasma polymerisation coating methods, we are able to apply the metallic heating layer, the mirrored surface and abrasion resistant coating all in one continuous process."
Dr Murphy says the goal is to develop a process requiring less human handling, greater efficiency, and greatly reduced yield loss with much less material wastage during manufacture.
"On an industrial scale it will mean raw plastic beads can be poured into an injection moulding machine at one end, and at the other end, we will have a fully coated mirror.
"The advantage of the plasma polymerisation coating technology over dip coating is that it allows much greater process flexibility.
"When you use a dip coating method you’re stuck with the properties of that dip, which on an industrial scale could mean a huge amount of liquid – this new technology allows adjustment of the abrasion-resistant coating from mirror to mirror if required."
Having subjected the car mirrors to a rigorous testing process, including 10 years of environmental extremes in just 40 days, the team is confident the market will embrace the technology.