Plastics get a splash of colour

Bored with hi-fis and televisions in those uniform black casings? If a revolutionary invention by Warwick Manufacturing Group's Gordon Smith is taken up, hi-fi and television makers using plastic for casings could make more colourful products in the future.

The process allows "in-mould" painting of plastics that are injection moulded, and was originally developed for the car industry. Rover will be using the process on one of the exterior trim components for its next model. Other expected applications include exterior body panels and interior trim.

Dr Smith explained that with conventional methods of painting plastic components have to be painted in paint shops after being injection moulded. With the new process, environmentally-friendly paint in granular form is injected directly into the machine. In practice the paint is injected into the mould first, followed by the plastic, which "blows out" the paint so that it becomes the skin of the component.

Dr Smith says the development offers major environmental benefits through the elimination of paint shops, so avoiding volatile emissions and effluent. Direct cost savings are also substantial. Dr Smith estimates that a typical automotive component supplier's paint shop costs between Pounds 5 million and Pounds 20 million.

Other benefits of the process include longer tool life, since the paint acts as a "protective layer" within the tool, its surface protected from damage by the core material.

He says that components ranging from television cabinets to cosmetics cases can be "painted" using the new method. It has already been used to produce a silver casing for a television and coloured lipstick cases. Dr Smith has even used the technique on a toilet cistern. "In-mould painting produces a one-step process direct from the mould which matches all current standard paint finishes."