PAINT & POWDER
chemical and climate change tests , which are important for international vehicle construction .
Future-proof investment
For powder coating , WELCO relied on manual work and Venturi technology until 2015 . “ To achieve a decent coating quality was high in every aspect ,” recalls Mr . Nuber . “ We sprayed to waste and needed two minutes or more to coat complex workpieces . Around 13 % of the parts still had to go to post touch up .” Even after that , the film thicknesses fluctuated greatly from coater to coater . There were high costs for system maintenance , wear parts , repairs and downtime . “ It was clear that only an automated powder coating process could optimize quality and reduce the effort to an acceptable level . Three goals were important to us : a high quality of powder coating , automatic handling of wear and spare parts and the economic efficiency ,” Mr . Nuber continues .
After researching Mr . Nuber became aware of the Nordson dense phase technology . In order to test this technology for its own application , the WELCO team gladly accepted the offer from dense phase pioneer Nordson to carry out initial tests in their test lab in Erkrath . “ We tested our parts with the Encore ® HD manual coating powder guns and the application itself immediately convinced us that a process that could be controlled completely and safely with hardly any overspray at a high penetration depth of the powder . However , the conventional reciprocators were not flexible enough for our complex parts . For a high degree of automation , we had to think of robots .”
“ This was also an exciting new task for us ,” says Jörg Zimmerhackel , Project Manager of the WELCO plant ( Managing Director of CS Oberflächentechnik and southern German representative of Nordson ). “ We agreed to develop a completely individual solution for WELCO and were awarded the contract .”
Even the configuration of the ColorMax ® fast color change booth proved to be a difficult task . “ The available area for the booth was only 20 sqm . There had to be enough space for the two robots and their movements . The height of 2.50 m without substructure was not allowed to be exceeded ,” as Mr . Zimmerhackel describes the challenges of the planning and construction phase . “ In addition , further openings in the booth had to be provided for the accessibility of the robots .
This made it difficult to create a gentle , uniform air flow in the booth , but we were able to successfully build a solution .”
The booth was designed according to the customer ’ s specifications and the dimensions were transmitted to the robot manufacturer , who extensively simulated the mobility of the two compact , staggered 7-axis robots . Only thereafter did the construction of the powder coating booth begin . “ ColorMax booths that are modified in this way to meet customer specific requirements are given the suffix “ E ” for Engineered ,” explains Mr . Zimmerhackel . “ This one is designed for parts up to 1,200 x 600 x 600 mm in size and is equipped with standard components from the ColorMax3 booth ”.
The floor and sides of the booth were made of powderrepellent coated panels , and the slight overspray at the floor is directly removed by the AirWash system . Each of the two robots are equipped with an Encore HD automatic gun for the powder application itself . The robots are programmed quickly and easily in a point-to-point process .
The components of the system are supplied with fresh powder from the Spectrum ® HD powder center . The self-cleaning HDLV ® pumps and transfer pumps are used for powder delivery . These pumps carry the powder from the hopper to the guns and gently return the reclaimed powder to the Spectrum HD powder center . A Nordson self-cleaning twin-cyclone is used for gentle powder recovery , with an hourly output of
40 DECEMBER 2020 twitter : @ surfaceworldmag