Solvent vapour degreasers upgraded in Germany

Kumi Solutions has supplied VW in Hanover, Germany with two Pero V2-Universal vacuum solvent vapour degreasers to replace aging equipment.

VW in Hanover, Germany has replaced an ageing washing and degreasing plant with two Pero V2-Universal vacuum solvent vapour degreasers.

The Pero units allow VW to clean 1200 tonnes of aluminium oil cooler components a year using just 358kg of solvent - the equivalent of only one gram of solvent per basket of parts.

Pero systems and solutions are distributed exclusively in the UK by Kumi Solutions of Kenilworth.

"We simply had to do something", declares Reinhard Ludwig, a key figure in oil cooler planning at the VW factory in Hanover.

"Our old unit had become notorious for its ever increasing maintenance, repair costs and high consumption of neutral detergent".

With a general overhaul imminent VW began to weigh up its options: should the new plant work with an aqueous solution like the old machine, or with an organic solvent? "Water is not the only solution", states Robert Huber, sales manager with Pero.

"Aqueous systems pose their own problems with regard to protection of the environment and compliance with the latest wastewater regulations.

Aqueous plant also requires constant monitoring and frequent cleaning of the baths".

These reasons, along with lower costs, improved process safety and better cleaning results were the primary factors why Pero subsequently proposed a solvent-based washing and degreasing system to VW.

"Our parts must be extremely clean so that the flux for soldering operations, which take place after cleaning, can be applied properly," explains Ludwig.

"What we require are metal surfaces completely free of contamination.

Twice per shift, random samples are taken and examined for surface cleanliness and solderability".

The advice of Pero and a number of cleaning tests convinced the decision makers at VW that a solvent-based plant was the way forward, leading to the acquisition of two Pero V2-Universal vacuum solvent vapour degreasers, both designed for use with Dowclene 1601, a modified alcohol.

VW also installed a DB 300 vacuum distillation unit that removes oil from the degreaser at the same rate at which it enters the system.

The two degreasers are installed in series at the Hanover factory, with the baskets loaded automatically into the machine from an open driven roller conveyor.

A single controls both cleaning machines as well as the roller conveyor.

At present an operator places baskets on the conveyor, removes baskets at the machine outlet and transports cleaned parts to the relevant internal station.

In the future VW envisages a fully automated process where the baskets of oil cooler components are moved directly from the presses to the degreasers.

The two Pero units have also saved VW a considerable amount of space - the previous acqueous plant required three times the footprint.

Yet while this may be the most visually apparant difference between old and new, it is certainly not the most important.

What might not be clear at first sight is the enhanced performance of the new machine.

The specifications required a high throughput rate of 72 baskets per hour (or 36 per machine), which is of course achieved comfortably by the Pero units over a thee-shift work pattern.

Per cycle each V2 unit processes four baskets in its vacuum processing chamber.

The baskets are transferred automatically to the chamber by a driven conveyor.

After a leakage test at a pressure of 50 millibar, the parts are cleaned and dried in a series of processes under vacuum.

Following preliminary cleaning using the medium from tank 1, the parts are rinsed with medium from tank 2, which is kept oil-free by means of a sophisticated distillation process.

The parts are subsequently vapour degreased, whereby the last residual grease and oil is removed.

The combination of tried and tested condensation methods and innovative vacuum technology ensure that the parts are completely dry and free of odour when they leave the processing chamber on the conveyor belt.

Each cycle takes just 6.5 minutes Both machines are equipped with an integrated distillation system used to continuously clean the medium in the bath.

The separate vacuum distillation unit, which is installed beside the degreasers, is alternately connected to the machines.

It is filled from the machine stills with solvent containing oil, which is then distilled at a low temperature and returned to the rinsing tanks while the residual oil is collected in drums.

Thanks to this bypass cycle, the solvent used in the degreasers is kept oil-free and thus highly effective.

"We analyse the solvent every three weeks so that we can be sure that our machine runs only with a solution that is highly effective," says Ludwig.

In the distillation units oil is separated from the solvent.

It can be disposed of safely and at low cost as waste oil via the supplier of the Dowclene solvent.

The degreasers will be serviced and cleaned once a year, during the work holidays of VW.

For this purpose, they must be emptied.

However, the collected solvent can be processed through the vacuum distillation system and returned to the machines after they have been cleaned and serviced.

The new Pero machines have also provided VW with one other very important benefit, as Huber explains: "With just 385kg of fresh solvent being added per year, the machine does not come under the 31st Federal Immission Protection Ordinance, which only covers machines where more than 1 tonne of solvent is used each year.

The people responsible for production at the VW plant in Hanover know that they could install another two Pero V2 degreasers and still be clearly below the 1000kg limit".

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