As motor makers push the boundaries in automobile design in every direction to both save on manufacturing costs and provide increased safety for occupants, along with ever greater fuel efficiency, the trend to incorporate aluminium structure with high strength steel and composite plastic materials is forging ahead.
So you can now quickly forget about doing aluminium in a single special working area. From now on it’s going to be a multi-mix repair station and some of the big drivers in this new trend are Audi and VW with the TT3 model lightweight construction. This requires in real terms, even more investment in equipment standards in the multi-mix repair station of the future. The use of the VAG integrated model platform MQB is extended across the group architecture with their new VAS 6673 level of recommended and future requirements is unveiled.
With the new concept of bringing together all the body materials like aluminium, hybrid steels and composite materials, in reality this means that the area now becomes effective as an often curtained off area for everyday workshop use. Thus the investment can work as a powerful tool for daily business. As usual with an advantage there is normally a downside which is ever present and the emissions of these new material substrates in repair come under a hazardous substance ordinance across the world.
Often this necessitates a special assessment for local health and safety and fire laws and all the responsibilities for compliance fall in the bodyshop owner’s lap. Sadly as a repairer you now need some chemical, physical and legal knowledge to repair this multi-mix type of vehicle.
Let’s start with the dust coming from the aluminium steel and CFRP fibreglass. Aluminium dust is flammable and can be deemed to be explosive depending on the concentration of dust and its particle size.
If a fire does start and a worker throws water on the dust it will explode into a ball of fire or produce toxic hydrogen gas in what is called a thermic reaction that burns at 2 400°C and often needs special extinguishers to stop the spread of the fire. Water will only add to your troubles should there be an accidental fire in the workshop.
From a health aspect recycling aluminium dust is a hazardous activity. Due to its static electricity component, CRP dust is also harmful if inhaled causing splinters which are very fine and can enter an operator’s lungs. It also attacks smartphones and computers in close proximity. Along with this list of processing red flags are the rust and dust that will cause heat when being removed. These too can cause a thermic fire.
If you’re not very careful by now perhaps you are beginning to realise that an ignition of these dust materials can easily burn the shop down and kill people as it did recently in China in the mag wheel factory where 86 people were killed. The factory was flattened when aluminium dust suffered a thermic explosion due to an ignition source from a maintenance worker on site.
Enter the Vacuum
The number one priority is to eliminate external sparks (which are vey common) via a spark trap, the sparks enter the trap at 200 km/h and are disintegrated by the TUV approved spark trap. The particles are then returned to 200 km/h in the five metre calming pipe before entering the ATEX vacuum machine. This process eliminates potential external ignition sources from entering the machine which itself protects the contents from its own ignition source such as electric motor and static charge (Attex 3 IID).
Most body shop owners don’t realise it is their responsibility to ensure the correct usage of any equipment, therefore it is critical that the equipment is used in accordance with the owner’s manual by the manufacturer of the machine and approved by an independent authority such as TUV on its effectiveness.They often carry a full class H filter and fireproof rating but even with all this it’s best to keep the different waste dusts separate. Working clean at all times will reduce the ever present fire risk.
“This is the best safety device out there,” says Bernd Himmelreich of ProWoTech GmbH, who are based in Germany and who presented a talk recently on handling these multi-mix hazards in repair.
Further to This
It is interesting that VWG were among the OEMs that pushed for dedicated aluminium working rooms inside conventional repair shops. The advent of multi material body structures has been underway for some years, as can be seen clearly on the Mercedes-Benz C class W205. The image below is an aluminium strut tower – for the rear suspension of S class W222, which is very similar to that used on W205.
If one does no house keeping (removing dust as it accumulates) and no segregation of tooling, then problems will come very quickly.
Yes, build up of particles smaller than 420 micro metres across combined with a build up of static electricity charge can result in an explosion. Automotive Refinisher magazine explored this subject in the March 2015 edtion.
However, good housekeeping can result in not using dedicated aluminium processing rooms and no risk of explosions. More critical is the advent of bonded joints which require excellent process control to achieve the correct cured joint strength. So, by all means get the super dooper vacuum device, but it won’t solve all the issues by itself. It requires good processes, and clean working areas too.