Innovative Tub Vibrator Concept for Better Quality, Higher Efficiency, and Improved Competitive Standing. Plastification augers for melting plastic pellets are an essential part of every injection molding machine. To offer equipment that guarantees maximum quality and precision in an extremely competitive market, the globally active Engel Austria GmbH produces these augers exclusively at its Austrian manufacturing location in St. Valentin. The investment in two fully automated mass finishing machines from Rösler ensures not only more cost-efficient production but also consistently high quality. The automation concept allows the operation of the tub vibrators and directly linked cleaning system with minimal personnel requirements. Since the optimized polishing process helps substantially reduce processing times, this trend-setting equipment concept will certainly prove useful for other industrial applications.
In cooperation with the Austrian automation specialist Promot, Rösler created an integrated system that optimally links the various equipment components. The workpiece fixtures, specifically developed for this application, guarantee maximum operational efficiency and finishing quality. Moreover, the set-up times were significantly reduced. Last but not least, by expanding the finishing system to two tub vibrators, the capacity for polishing plastification augers—up to three meters long and 15 to 80 mm wide—was substantially increased.
Automatic loading of the tub vibrators with minimal handling times
The injection molding machinery manufacturer Engel has been using Rösler finishing equipment for more than 20 years. Until recently, the company polished plastification augers in a tub vibrator with a single-stage finishing process. This involved time-consuming manual workpiece handling, requiring significant manpower, especially for loading and unloading the workpieces into and from the finishing system. Therefore, the customer’s specifications called for a reduction of the physically demanding handling work for employees and for automatic loading and unloading of the tub vibrators.
A key role in this challenging project was played by the expansion of a gantry crane system by the Austrian automation specialist Promot, which has already been successfully employed for loading and unloading the grinding machines used in a preceding finishing operation. Furthermore, the new mass finishing system had to be able to handle the production volume of plastification augers specified by Engel. Based on the existing polishing process with an average cycle time of 8.5 hours, this would otherwise have required several new tub vibrators.
Two-stage process significantly reduces processing times
The main focus of the Rösler engineers for this project was to reduce processing time and minimize the required number of tub vibrators. Both goals were achieved by utilizing a two-stage Keramo-Finish® process that runs simultaneously in two tub vibrators, model R 800/3200 TSD-15. These machines, equipped with special direct-drive vibratory motors, are extremely productive, allow flexible operation, and require very little space.
By reducing the overall roughness value to Ra < 0.1 µm, the two-stage Keramo-Finish® fine-grinding and smoothing operation in the tub vibrators drastically improves the surface finish. This is the key reason for the excellent quality of the plastification augers. The streamlined finishing operation, in combination with the powerful equipment, also helped substantially reduce processing times. Additionally, the improved surface quality of the workpieces entering the Keramo-Finish® process was a positive factor. This is achieved by using fine grinding media that provides a relatively high metal removal rate while creating a fine surface finish.
Loading of the tub vibrators with a gantry system and optimized setup concept enables a fully automatic polishing operation
To allow fully automatic workpiece loading and unloading of the tub vibrators, Rösler developed an automation and control concept for the gantry system in close cooperation with Promot. It transports the plastification augers after the pre-grinding operation to the workpiece setup and mounting station. There, an operator places a certain quantity of augers, depending on the auger size, into a mounting frame.
Mario Stollnberger, Manager of Plastification Activities, explains: “In the past this setup operation was very time-consuming, because both ends of every individual auger had to be mounted into the frame separately. Today, this is done by simply placing the augers into the mounting frame utilizing a floating positioning system. This has cut the setup times to around 15 minutes.”
In the next step, the gantry system picks up the mounting frame—now loaded with workpieces—transports it over the tub vibrator, and then lowers it onto special guide rails positioned in the vibrator tub. This clever concept allows the mounting frame with workpieces to freely rotate in the processing media. In addition, it offers the advantage that upon completion of the finishing cycle the entire frame can be fully automatically removed from the tub vibrator.
The placement and removal of plastification augers into and from one mounting frame take place while the workpieces in another mounting frame are being processed. This simultaneous workpiece loading/unloading and processing function further improves the overall efficiency of the polishing process.
Besides the two mass finishing vibrators, the new polishing cell includes a workpiece load/unload station, a workpiece cleaning system specifically developed for this application, and a fully automatic centrifuge, model Z 1000, for cleaning and recycling the process water in a closed loop, thus saving valuable natural resources.
Innovative automation concept offers many possibilities
Tub vibrators can be used for numerous finishing applications. However, until now it was practically impossible to automate the workpiece loading and unloading operation for these versatile mass finishing machines. With the newly developed, innovative automation concept, Rösler now has a solution that will make finishing operations in other industries—such as aerospace—more efficient and faster.
For Information:
Rösler Oberflächentechnik GmbH
Vorstadt 1, 96190 Untermerzbach
Germany
Tel. +49.9533.924-802
E-mail: d.hund@rosler.com
www.rosler.com
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