Optimized finishing process with a new, non-foaming plastic media

Better results, higher productivity and improved cost-efficiency

In general, the optimization of mass finishing processes is mostly focused on the machinery. A finishing application at the job shop company Dörfler & Schmidt Präzisionsfinish has shown that by simply using a different media, a significant process optimization can be achieved. By switching to a new, non-foaming plastic media from Rösler the customer achieved a higher process stability, higher productivity and an improved efficiency.

Founded in 1998, the Dörfler & Schmidt Präzisionsfinish GmbH offers a wide range of surfaces, such as deburring, edge radiusing surface smoothing, polishing, creating mat and structured finishes, descaling and cleaning. For these services the company is utilizing mass finishing, shot blasting and brush deburring equipment. The company is treating work pieces made from metal, plastic, ceramic, glass and wood. The work piece dimensions can range from a few mm up to 60 centimeters. The customers of this family-owned company, located in Kammerstein in the state of Bavaria, come from all kinds of industries like automotive, machinery building, electronics, medical engineering, jewelry and a variety of consumer goods manufacturers.

A company utilizing different types of mass finishing technologies
The highly heterogeneous clientele of Dörfler & Schmidt requires all kinds of surface finishing solutions. Felix Dörfler, executive assistant, comments: „We have to deal mostly with requests for deburring and edge radiusing. For example, on tools like milling tools and cutting inserts we have to create a precise edge radius. Other work pieces, such as bearing rings must have precisely defined surface roughness readings after the finishing operation. On the other hand, jewelry and accessories must have an optically pleasing finish.”
To be able to offer its customers the technically and economically best solutions, the company operates 33 different machines that can handle a broad range of different mass finishing technologies. Felix Dörfler continues: „To handle the various work piece materials we employ different process water cleaning and recycling systems. For this purpose we are utilizing five centrifuges, which like the overwhelming majority of our mass finishing equipment, were supplied by Rösler.” When it comes to consumables, Dörfler & Schmidt is also primarily using Rösler products. “The consistently high quality of the Rösler media and compounds and the excellent support in the field of process development and optimization by the Customer Experience Center are just a few reasons that right from the beginning we relied on solutions from Rösler”, concludes the executive assistant.

New plastic media suppresses foam that interferes with the finishing process
Mass finishing processes with plastic media pose frequently a problem with foam, even when so-called foam-reducing media are used. The extent of the foaming issue depends to a large extent on the hardness of the process water used in the finishing process. For resolving this problem, frequently special additives are utilized. This was also the case with an application at Dörfler & Schmidt. Felix Dörfler explains: „For the deburring and edge radiusing of 40 mm long stainless steel wire segments we need an excellent grinding performance with a high metal removal rate. However, the foaming during the finishing process created a buffer between the work pieces and the media, which reduced the grinding effect. Therefore, the desired finishing results could no longer be achieved within the prescribed cycle time”. But the unwanted prolongation of the cycle time was not the only problem. The separation of the finished work pieces from the media was also affected and did no longer function properly. The foaming issue was even carried over to the process water cleaning system, where foam was seeping out of the centrifuges. This soiled the system itself and the immediate environment.

When the responsible Rösler sales agent was informed about this problem in July 2020, he proposed the use of a non-foaming plastic media that had recently been developed by the Rösler process engineers. Since the beginning of 2021, Rösler offers all standard plastic media types also in the non-foaming “N” version, which regarding the shape, size and grinding performance is identical with the old product.
Since the use of the new media required no modification of the finishing process at Dörfler & Schmidt, the company replaced the old media with the new, non-foaming version.

Higher process stability, improved efficiency and higher sustainability
Dörfler & Schmidt is one of a selected group of companies who have tested the new media. The company has now been working with the non-foaming version for about nine months. The first test phase demonstrated impressively that the required processing results are safely achieved within the prescribed cycle time and that the separation phase also works well. The media switch to the non-foaming version has also greatly simplified the monitoring of the finishing process. Since the time for unwanted re-work could be completely eliminated, the overall cost-efficiency was significantly improved. Another benefit of the new media is that the usable life of the process water could be extended. This helped reduce the consumption of additives, a big plus for the environment and for achieving sustainability.

Felix Dörfler summarizes: „We have been using the non-foaming media in two machines. And we have found that the grinding performance and the wear rate are absolutely identical with the standard version. The new media helped us to make our processes more cost-efficient without affecting the quality of the finishing results. For this reason, we will switch more plastic media types to the non-foaming version”.