Deburring demanding injection molded parts individually and in a continuous process

A manufacturer of injection molded parts produces parts previously made of metal from thermosets and thermoplastics. This necessitated a capacity expansion for deburring the components, and the choice fell on a blasting solution.

Lighter, more compact and more sustainable - a manufacturer of injection-molded parts is proving that this trend can be implemented cost-effectively with high-performance plastics. The company is increasingly producing parts from thermosets and thermoplastics that were previously made from metals. This necessitated an increase in capacity for deburring the components. The choice fell on blasting solutions from Rösler. The RSAB 470 wire belt system ensures fast and efficient processing in continuous operation. In the RWS 1200 reversing beam system, the workpieces are deburred reliably as individual parts. The two-stroke design minimizes unproductive downtime.

The processing of plastics has an almost 100-year tradition at Ros GmbH & Co. KG, which was founded in 1926 as Presswerk Ros. Now in its third generation, the family-owned company is a high-end partner for technically demanding injection molded parts made of thermosets, thermoplastics including polyphenylene sulfide (PPS). Development, moldmaking and production are located at the company's headquarters in Coburg, while production also takes place in Ummerstadt, Thuringia. Since 2006, the company has been using blasting systems from Rösler to remove the burrs that arise during the process.

"The fact that we had to expand our blasting capacity at both sites in 2021 was due on the one hand to an increased volume of plastic components that substitute metal parts, for example thermal management systems for the automotive industry. They make it possible to save weight and thus reduce CO2 emissions. On the other hand, we have received large-volume new orders for the production of thermoset molded parts, among others from a major manufacturer of gardening equipment," reports Jürgen Bär, responsible for technical planning in the Industrial Engineering department at Ros in Coburg. After discussions with four blast machine manufacturers, the decision was made in favor of the RSAB 470 wire belt continuous blast machine and the RWS 1200 reversible beam blast system from Rösler. "The deciding factors were the good experience with the existing systems, the compact design and solid construction, and the company's extensive experience in blasting plastic parts," notes Jürgen Bär. "In addition, we needed the continuous blast machine very quickly and Rösler offered to deliver the machine from their Customer Experience Center at short notice."

The flexible high-performance RSAB 470 system is used at the Coburg site for continuous deburring of injection molded parts made of thermosets and the high-performance thermoplastic PPS-GF. Processing is followed by annealing, for which the parts are placed on special racks. To minimize the manual effort required for parts handling and to eliminate the loose placement of parts on the wire eyelet belt of the shot blast machine, Rösler adapted the standard workpiece transport system to the workflow at Ros. This allows the annealing racks to be loaded with parts directly after injection molding, deburred on the fixtures and fed to the annealing process. For a process-reliable and reproducible blasting result, the system has four turbines developed for plastics processing, which are placed above and below the belt. They apply the abrasive - a polyamide grain with an edge length of 1 mm - to the parts from above and below at a highly accelerated rate.

In contrast to injector blasting technology, which is usually operated with compressed air, turbine blasting technology is considerably more energy-efficient with the electric drives used. "Possibilities to implement energy savings are not only demanded by our DIN EN 50001 certification, a reduction in energy consumption is also urgently needed today from a sustainability and cost perspective," adds Jürgen Bär. An abrasive monitoring system with automatic re-dosing ensures that the abrasive is always used in optimum quality. The antistatic system with automatic re-dosing, the blasting chamber extraction, a two-stage cleaning of the parts in the discharge zone of the system as well as the effective blasting medium preparation with sieving device and cascade wind sifting also contribute to the fact that the parts come out of the system deburred and clean as required. Since the materials used at Ros and the polyamide abrasive can generate explosion-critical dusts, the systems were equipped with special, ATEX-compliant filter systems.

The RWS 1200 reversible beam blast machine, which has expanded the blast capacity at the Ummerstadt plant, is used for components made of PPS-GF with an enveloping circle of up to 163 mm. In line with the production cycle of the injection molding machine, four workpieces are deburred simultaneously within the specified time of 40 seconds. For this purpose, the system has two areas, each equipped with four satellites. This design allows loading and unloading to take place in parallel with the deburring process. Unproductive downtime is minimized. For energy-efficient operation, a turbine applies abrasive from above to the parts on the diamond-shaped satellites, which not only rotate but can also stop in a part-specific angular position. In areas not reached by the turbine's abrasive due to geometry, injector blast nozzles with pressure monitoring on a vertically movable unit ensure precise deburring. In addition to the stroke movement, the nozzles can be positioned precisely in front of the parts by means of a distance measuring system, whereby both oscillating and spot blasting is possible. "To minimize compressed air consumption here, we work with part-specific processing programs," reports Jürgen Bär. The RWS 1200 is also equipped with automatic re-dosing for the abrasive and the antistatic medium, a blasting chamber extraction system and abrasive preparation. (OM-05/23)