Fully automatic production ensures competitiveness
There are very few automotive manufacturers who do not purchase their rear view mirrors, or parts thereof, from Visiocorp Deutschland GmbH (formerly known as Schefenacker Mirrors GmbH) located in Southern Germany near Stuttgart. The company is not only strong in product development, sample production and design, but also manufactures aluminium die cast mirror components for numerous automotive assembly plants all over the world. Christian Barth, who manages the metal fabrication department at Visiocorp says: „to maintain our competitiveness at our German location we had to implement fully automatic manufacturing technologies.“
Top quality requirements – not only for the surface finishing process
After vibratory finishing the mirror components are either painted or utilized without any further surface finishing step. In both cases a surface free of flash and other particles as well as free of oil is required. The complete range of over 100 parts, weighing 50 – 2,500 grams must be processed in the finishing machine. Christian Barth describes his requirements as follows: „The streamlining of the finishing process, the increase of productivity, a high system uptime in our 18-shift operation, top equipment quality and its adaptability to our special operating conditions were all very important.“ Based on these criteria a Rösler R 550/4600 linear continuous vibratory system was selected. This system is fully integrated into the die cast operation. To keep the noise level at a minimum for the surrounding manual work stations the complete system was placed into a sound enclosing cabin keeping the noise level at <78 dB(A).
Automatic parts loading from another floor
The delicate parts are transported to the vibratory finishing system from another floor via a special „elevator“. This simplifies material handling considerably and minimizes personnel requirements. The PLC with 20 different processing programs allows the optimum surface finishing of all the different parts groups. The “elevator“ transports one parts bin at a time into the first floor and lifts/rotates the bin by 180 degrees. A hold back flap prevents parts from prematurely falling out of the bin and nicking each other. Once the bin has reached its unload position, the flap opens and the parts slide onto a vibratory buffer conveyor.
Finishing of up to 1,950 parts per hour
The parts transfer from the vibratory hopper into the finishing machine is controlled by weight per unit of time. The current throughput amounts to about 650 parts in 20 minutes. A second vibratory conveyor disentangles the parts and transfers them to a conveyor belt which in turn transports them into the finishing machine. This sophisticated load system was necessary, because the parts tend to get tangled with each other. The finishing machine, with a channel width of 550 mm and a channel length of 4,600 mm, allows a gentle deburring and de-greasing and produces a homogeneous surface finish. The media utilized for the process are 40 mm pyramids type RKM. The powerful, variable speed drive and the fact that the work bowl is floating on 4 adjustable air cushions allow variable processing times.
Separation of finished parts and media takes place in an independent vibratory screening machine with two integrated steps. The screening unit was designed to minimize drop heights and, thus, prevent part-on-part impingement of the delicate components. After separation the finished parts are transported through a hot air belt dryer from where they are transferred to a special buffer belt with a pair of two-directional tracks. The last step is a 100% visual check of the finished parts. Says Mr. Lösch, colleague of Mr. Barth: „This system offers a high productivity and excellent, totally repeatable finishing results“. Christian Barth adds: „The high productivity was mainly achieved by the automatic loading system. This allows us to run the machine with 1.5 people. We would not have achieved this with any other system available in the market!“
As an all-round supplier, Rösler GmbH is an international market leader in the production of surface finishing, shot blasting machines, painting systems and preservation lines as well as process technology for the rational surface finishing (deburring, descaling, sand removal, polishing, grinding…) of metals and other components. Besides the German plants in Untermerzbach and Bad Staffelstein, the Rösler Group has branches in Great Britain, France, Italy, The Netherlands, Belgium, Austria, Switzerland, Spain, Romania, China, Brazil, South Africa and USA.