Volkswagen Group South Africa’s (VWSA’s) paint shop has launched a project which reduces hazardous waste at the group’s Eastern Cape assembly plant, by improving painting efficiency levels.

The project sees the replacement of the painting technique used at the plant with a 100% electrostatic process, called the Bell Bell process.

“There are two different application processes – one for uni-base colours, for example red, white and black, and a second for metallic colours, for example, silver or shadow blue,” explains Volkswagen manufacturing plant paint shop head Nico Serfontein.

“The first application process employed in Base Coat Station 1 is used for all colours, uni-base and metallic, and is referred to as an Esta or Bell application.

“The second, more conventional application process, is used in Base Coat Station 2, where only metallic cars are painted for a second coat. This system works on the same principles as a manual spray gun, except that a double gun configuration is mounted at the end of a robot arm. It is referred to as a Spraymate System.”

The main advantage of the Esta system used at station 1 is that it uses electrostatics to improve the transfer efficiency of the atomised paint. This means 70% of the paint goes onto the car, with the other 30% disposed of as waste.

The advantage of the Spraymate system is that it improves the colour appearance of the painted surface, but unfortunately only has a transfer efficiency of 35%, with around 65% of the atomised paint going to waste.

The Spraymate application technology was the only one available when the new paint shop was built in 2006. However, since then, a new application system has been developed which not only uses electrostatics for improved transfer efficiency, but also produces the desired paint surface quality.

The Uitenhage-based plant is the first paint shop in the global Volkswagen Group to introduce the water-borne Bell Bell painting process – it has only ever been done on solvent-borne paint.

VWSA says paint use has now been reduced by as much as 50% at the robot station. Less compressed air is also used, which results in increased energy efficiency.

With the Bell Bell painting process, the application is a lot softer;
therefore. over-spraying is lessened, which results in fewer chemicals in the washout area. This, in turn, has lowered volatile organic compound emissions at the plant.

“This advanced technology is in line with the Volkswagen Group’s Think Blue.Factory strategy, which aims to reduce the environmental impact by 25% per car produced,” says VWSA’s MD David Powels.