Fully automatic processing line including periphal equipment and electronic controls
A new centrifugal disk finishing system from Walther Trowal allows the deburring, surface smoothing and polishing of metal components in one single finishing line. This represents a major step towards streamlining surface finishing operations. The new TT 280-A/2C system operates fully automatically – from loading the aligned raw work pieces into the processing bowl to discharging the polished and dried components.
Development for this innovative finishing system was initiated by a manufacturer of furniture fittings. This company had decided to discontinue the surface finishing of piston rods for dampening systems by external subcontractors and bring the operation back in-house. Main goals of this move were to improve the surface finishing quality, to better control the production costs and to manage the overall capacity utilization more effectively. Specifically, the company looked for a finishing system that allows fully automatic deburring, surface smoothing and polishing in one single process.
The piston rods are used in dampening systems for furniture and kitchen appliances, such as soft-closing systems for drawers and hinges for the doors on ovens, dishwashers and refrigerators. Per day the company produces hundreds of thousands of stainless steel piston rods with lengths from 20 to 100 mm and a diameter of 2 mm. To function properly the piston rods in the dampening systems require an extremely smooth surface and precise, consistent edge radiusing. In addition, they must be perfectly aligned. Finally, the fully automatic packing of the finished components demanded absolute batch integrity, i.e. work pieces from different batches cannot get mixed up.
Based on these requirements Walther Trowal proposed a fully automatic processing line based on the proven Turbotron double batch centrifugal disk finishing concept. In this system the process steps deburring, surface smoothing and polishing are sequentially integrated into one single operation. The first machine is utilized for deburring and surface smoothing. Then a conveyor belt transports the pre-treated work pieces into the second machine for polishing. The entire operation, from the loading of the raw aligned piston rods to the transfer to the packing station, runs fully automatically. All the machine operator must do is load the work pieces into the first machine and discharge the polished and dried piston rods from the second machine with an automatic work piece transfer system.
The unique double-batch concept of the Trowal centrifugal disk finishing machines minimizes idle equipment times and ensures high capacity utilization: While one batch of work pieces is finished in the processing bowl, a second batch of already finished work pieces is passing through the separation system, where they are separated from the processing media.
In both centrifugal disk finishing machines plastic media is utilized. Both the deburring/surface smoothing and polishing process are running with a high-water level in the processing bowl. The water cushions the pressure exerted by the media on the work pieces and makes the operation particularly gentle. This ensures that the delicate piston rods are not deformed and guarantees a high finishing quality with precise and consistent surface roughness readings. During the deburring/surface smoothing process the edges are radiused to a precisely defined radius.
100 percent batch integrity – no mix-up of different work piece batches – is achieved in two ways: The special design of the Trowal centrifugal disk finishing machines ensures the complete and safe unloading of the finished work pieces from the processing bowl. And in the separation unit the media/work piece mix is passing over a precise bar screen that allows the consistent separation of the work pieces from the media. This guarantees that no residual media can migrate into the packing station.
The polishing step in the second centrifugal disk finishing machine is followed by a drying operation with eco-friendly maizorb drying media. The drying machine is equipped with a dust collector that removes any dust adhering to the finished work pieces. This ensures that the piston rods are transferred to the packing station absolutely clean and dry.
High surface quality piston rods 
The piston rods are part of dampening systems used, among other items, in the hinges of doors on ovens and dishwashers.
Walther Trowal supplied and installed the entire finishing system including peripheral equipment and electronic controls. Besides the high finishing quality this “turnkey” handling of the entire project was a major reason for awarding the purchase order to Walther Trowal.
