Heraeus infra-red drying for re-painted aircraft assemblies

A leading provider of integrated avionics, engines, systems and service solutions for aircraft manufacturers, airlines, business and general aviation, military space and airport operations has recently installed a new paint finishing line that incorporates infra-red drying of their painted assemblies.

After so many take-offs/landings, aircraft wheels are sent back to suppliers for refurbishment and stress fracture testing. This will often include new tyres and brake assemblies along with repainting of the wheel and brake assemblies.

Until recently, the painting and drying at this supplier was carried out on a relatively old paint line with an IR oven that was taking over one hour to dry the Acrylic paint. As part of a major investment, it was decided to modernise this line so they approached leading specialist suppliers of spray application and fluid handling equipment Hi Tec Spray who designed and proposed a completely new paint line utilising an indexing conveyor system with 11 stations.

For drying of the PU paint Hi Tec contacted IR Specialists Heraeus Noblelight who arranged for trials to be carried out with the customer at their test and development facility in Neston.

The result of the successful trials was a 116kW medium wave system comprising of three individual 38.5kW heating stations which were supplied through Hi Tec Spray along with the conveyor system and spray booth. Assemblies to be painted are first shot blasted to remove any old paint, it is then put through a non-destructive testing zone to confirm that there are no stress fractures, etc.

They are then loaded on an indexing conveyor ready for painting with a two coat PU system, with the wheel unit being rotated at each station to give even heat distribution and assisting the paint application by the operator.

Heat Station 1 is used to preheat the wheels or brake assemblies before the primer coat is applied. This ensures that the wheel is completely dry and allows the primer to flash off before the Polyurethane topcoat is applied in a wet-on-wet process.  coated assembly then passes to station 2 where the wheel or brake assembly are heated to the required curing temperature circa 1,100ËšC.

After six minutes the wheel or brake assembly passes into zone 3 where they are held at the required temperature for a further six minutes After leaving zone 3 there are a further three indexing stations which allows wheel and brake assemblies to cool down before being offloaded.

The IR system from Heraeus has reduced the original curing times by over 75%, a high quality finish and paint savings have also been an outcome of this investment.

www.heraeus.com