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Vibratory System Provides Fast and Cost-Effective Finishing of Aluminum Die-Castings

When it comes to high volume production of complex aluminum die-castings, numerous automobile manufacturers and suppliers depend on Kovolis Hedvikov a.s. as a valuable partner. In order to expand their capacity and achieve more flexibility in the overall manufacturing process, they purchased a new vibratory finishing system that can handle a wide variety of work pieces and could be custom engineered to fit into the available space at their facility.

Kovolis Hedvikov a.s. was founded in 1816 as an ironworking operation and has a long and eventful history. Since 1945, the company has focused entirely on aluminum die-casting. Today, Kovolis produces components from nine different aluminum alloys with different casting technologies like vacuum investment casting and rheocasting.

The R 550/4600 DA continuous feed finishing machine handles about 30 different die-castings with a maximum diameter of 12 inches.



They have a wide product range including; brakes, power steering systems, turbo chargers and compressors for air conditioning systems. Their customers are well-known car manufacturers and tier-1 suppliers who also employ Kovolis as an important partner for product development. In addition to production, Kovolis provides services for machining, heat treatment and surface finishing.

Fast and Gentle Surface Finishing

Jiri Buzek, manager of foundry III at Kovolis, explains the need for a new vibratory finishing system, "Our product portfolio underwent a drastic change in the past years. The trend goes more and more to larger and more delicate components, which require a vibratory finishing step after punch deburring for their downstream handling. Our existing finishing system was not designed for this and had also reached the end of its productive service life."

The new system had to not only cope with larger work pieces, but also had to provide a gentler finishing process, while maintaining high equipment uptimes and cost efficiency. However, above all else, the new finishing system had to be integrated into Kovolis' existing manufacturing operation, utilizing an existing work piece loading device and hot air belt drier.

The planning engineers at Kovolis submitted these specifications to two finishing equipment suppliers. The foundry manager continues: "We decided to go with the Rosler continuous feed vibratory finishing system, because it offers ample capacity, and Rosler met all our special technical requirements."

The single curve U-shaped cross section of the processing channel guarantees the optimum movement of the media and work pieces through the machine.



Another Important factor in the purchasing decision was the fact that, besides the equipment, Rosler can also supply all compounds and finishing media to the customer. This allows for a finishing process that is highly adaptable to the customer's work pieces.

Fully Automatic Feeding of the Work Pieces Every 30 Seconds

Rosler's continuous feed finishing system consists of a linear continuous feed machine, type R 550/4600 DA, with a usable length of 15 feet. The functions of Kovolis' existing work piece loading system and hot air belt drier were integrated into the overall system controls of the finishing system. "Rosler met all our technical requirements and provided valuable support in optimizing our finishing process," explains Mr. Buzek.

About 30 different work pieces with a maximum diameter of 12 inches are currently processed in the R 550/4600 DA. Since it can handle parts with diameters of up to 16 inches, this machine offers a high degree of flexibility for future work pieces.

In addition, the system for automatic work piece loading can be easily adapted to a new work piece loading system, which may be installed at a later time. Depending on their individual design the castings are fed into the finishing system at cycle times between 30 and 60 seconds. The single curve U-shaped cross section of the processing channel guarantees the optimum movement of the media and work pieces through the machine.

To prevent any damage to the delicate work pieces during the separation cycle, the multi-deck vibratory screening unit contains two steps with minimal drop heights.



This unique design produces perfect finishing results within a maximum processing time of eight minutes. The processing time can be adjusted by simply increasing the inclination of the processing bowl. Compared to systems with a separate vibratory discharge channel the work pieces are travelling through the machine at a constant speed. This prevents any jams, which could cause nicking or deformation of the work pieces.

Dual Stage Separation with Rinsing Station

To prevent any damage to the delicate work pieces during the separation cycle, a multi-deck vibratory screening unit was used, which contains two steps with minimal drop heights. The undersize media classification system is equipped with an adjustable bar screen, which allows Kovolis to decide at which dimensions undersize media must be discharged.

Since the finished die-castings do not undergo a separate cleaning step for the removal of media fines from their surface, the separation unit is instead equipped with a spray-rinse station. After the work pieces have passed through the hot air belt drier, they go straight to packaging or machining.

"We are certain that with the new equipment we will not only improve the quality of our finishing operation but, at the same time, will become more cost efficient," concluded Buzek.

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