One of the world’s largest automotive rearview mirror manufacturers has combined Indian architectural design with a high-efficiency, ‘green’ paint system at its new facility in Hungary.
SMR Automotive Mirror Technology Hungary is investing in a completely new plant in order to increase its automobile rearview mirror production capacity. The company has opted for an Eisenmann paint installation to paint plastic mirror housings. Besides the customized design, including application technology and robots, high flexibility and economy were crucial factors. The VarioCharger paint metering system has all these characteristics, plus several other innovative features.
SMR (Samvardhana Motherson Reflectec), a member of the Indian Samvardhana Motherson Group, is one of the world’s biggest manufacturers of exterior rearview mirrors for the automotive industry, supplying virtually every major OEM around the globe. Consequently, the group’s SMR Automotive Mirror Technology Hungary subsidiary made exacting demands for quality, throughput and flexibility for its new paint shop in Mosonmagyarovar, Hungary. However, the principles of the Indian Vastu architecture also impacted on the system’s technical design. This included, for example, the paint line being structured with three spray booths, without a foundation.
The mirror housings are loaded on frames and transported through the plant on a skid conveyor system. Unlike spindle conveyors, which work on the basis of a circular system and are conventionally used in such applications, the skid solution offers greater flexibility – not only in view of the frequent colour changes required but it also makes use of plant design. For example, stainless steel conveyors are used in the pretreatment section, as they are highlyresistant to oversplash. At the same time, the skid conveyor system permits a far more compact plant layout.
The SMR system further features a power wash system, drying oven and a cooling area for cleaning the parts. The parts are then moved to the first spray booth where a water-based primer is applied.
During electrostatic application of the water-based base coat in the second spray booth, the Eisenmann VarioCharger, which can be integrated with all commercially available paint robots, achieves not only reliable potential isolation, but also minimum colour change times and paint loss. To achieve this, the innovative paint application system features two parallel and connected metering cylinders that control the process steps of filling, painting and rinsing paint product. This allows one cylinder to supply the robots with paint while the other rinses and fills. This results in colour change times of less than four seconds.
Unlike conventional metering systems, the VarioCharger does not convey the paint by means of pigs but with the aid of the rinsing agent. The patented piston technology in the metering cylinder guarantees neat separation of rinsing agent and paint on the one hand, and precise ‘meterability’ of the rinsing agent and paint quantities on the other. This allows paint loss to be reduced to around seven millilitres which, in view of the numerous color changes, is a remarkable achievement. Compared with an average paint loss of approximately 50 millilitres in conventional systems, this represents an approximate savings of 86% per colour change, giving SMR a cost advantage, as well as improved efficiency in paint usage. Moreover, the VarioCharger system ensures precise measurement when using paints of different viscosities, which enables SMR to meet the exact specifications of various OEMs both easily and efficiently.
One other advantage of the VarioCharger is how easy it is to maintain the modular paint metering system. This is a result of the well-conceived design, which has made it possible to preserve those parts susceptible to wear, including: paint pumps, measuring cells, sensor systems and pigs. Only the filling line used by both metering cylinders operates with a pig.
The solvent-based clear coat is applied in the third spray booth. As in the two earlier booths, an automatic turning station is located upstream of the robot. It has been designed so that each of the spindles located on the base frame can be activated and turned individually.
The fully air-conditioned spray booths each have an air-conditioned clean room and a glass front panel in order to prevent the discharge of any dirt. An air recirculation system, which also features a direct evaporator, is used to condition the booth air. Excess heat generated by refrigeration is used to warm the recirculating air back to the required temperature after dehumidification.
This reduces energy usage, which contributes to the plant’s high efficiency levels. The flash-off and cooling zones, in addition to gas-fired ovens, are also operated in recirculating-air mode.
The water for wet scrubbing of the overspray is also recirculated, while paint sludge is also removed from all three paint booths via a common decanter. The plant features regenerative thermal oxidation for disposal of airborne solvent, in compliance with current directives on VOC handling.