VW introduces new paint technique to reduce waste

The project, which converts the painting technique to 100% electrostatic, called the Bell Bell process, has become a benchmark in the entire Volkswagen Group production network.

"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)," explained Nico Serfontein, head of the paint shop at the Volkswagen manufacturing plant in Uitenhage.

"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."

Advantages of systems

The main advantage of the Esta system is that it uses electrostatics to improve the transfer efficiency of the atomised paint, in other words 70% of the paint goes onto the car and the other 30% is disposed of as waste.

The advantage of the Spraymate system is that it improves the colour appearance of the painted surface but unfortunately it only has a transfer efficiency of 35% with approximately 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 but 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.
Uitenhage is the first paint shop in the Volkswagen Group to introduce the water-borne Bell Bell painting process - it has only ever been done on solvent-borne paint.

Less energy used

Paint usage has been reduced by as much as 50% at the robot station, where modifications are made (currently using half a litre paint less than before). 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 the volatile organic compound emissions.

"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," said Volkswagen Group South Africa's managing director, David Powels.