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Vol. 15
May Issue
Year 2014
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Articles


in Vol. 15 - May Issue - Year 2014
New Vibratory Finishing System Significantly Reduces Non-Productive Times For Deburring Of Internal Part Surface Areas



The work piece is electromagnetically clamped onto the magnetic plate. For this reason, it vibrates at the same frequency as the work bowl.


The VG 25 finishing system with peristaltic pump, abrasive media storage tank and vibratory work bowl


A casting mold for a beer mug after deburring and polishing

 In the Spotlight

For more than 80 years, Walther Trowal has been a pioneer and market leader in various surface treatment technologies. The company offers modular and custom-engineered solutions for a wide range of surface treatment problems. Initially only making vibratory finishing equipment, over the years, Walther Trowal has continuously broadened its product range and today offers a wide portfolio of equipment and services for improving all kinds of surfaces, e.g. mass finishing, part cleaning, shot blasting and drying of a wide spectrum of work pieces, last but not least, the coating of mass-produced small parts. Walther Trowal offers not only various types of equipment but complete surface treatment systems: By linking the various equipment modules and automating the complete process, we are able to precisely adapt our process technologies to the technical requirements of our customers. This also includes various types of peripheral equipment and process water cleaning and recycling systems. Of course, we also offer comprehensive pre- and after-sales service like sample processing in one of our demonstration labs and global repair and maintenance service. Walther Trowal serves customers all over the world in many industries, for example, automotive, aerospace, medical implants, and wind energy.

At METAV 2014 - A leading mass finishing equipment manufacturer presents the innovative VG 25 vibratory finishing system for deburring & grinding the complex and delicate internal surface areas of high value components. The proven MV surface finishing machines have contributed to drastically reduce processing times for fine grinding and polishing. Now, with the new VG equipment and its closed loop media transport system, this equipment supplier goes one step further by practically eliminating the non-productive times for media and part handling.

The VG 25 finishing system effectively removes burrs from complex parts with difficult-to-reach surface areas including internal passages. It ensures that delicate part contours are not compromised, and fragile ribs or cross-sections are not damaged. Even the inside of bore holes with diameters of less than 3 mm can be completely deburred.
Brand-new is the closed loop system for transporting the grinding media. With this innovative and unique concept, this equipment supplier could significantly reduce the non-productive times for loading and unloading the work pieces: After completion of the deburring process, a suction pump removes the whole media batch from the work bowl, allowing easy removal of the finished work piece from the magnetic fixturing plate and placement of a new raw part in the work bowl.
The first VG systems have proven that the complex internal surface areas of aluminum or titanium components weighing 30 - 40 kg (66 - 88 lbs) can be automatically and efficiently deburred within 2 to 4 hours. In comparison, manual deburring of the same parts takes at least one week.
Loose burrs in components used for the operation of complex systems, for example, hydraulic valve blocks, can cause system failures with catastrophic consequences. For this reason, such components require careful and complete deburring of all their internal passages.
The proven MV finishing systems have been demonstrated to be highly effective for such deburring tasks. And, compared to the Abrasive Flow Machining (AFM) with a grinding paste or the ECM electrochemical deburring, the capital expenditure for the MV equipment with part fixtures and the operating costs (including consumables) are considerably lower.
In the MV machines, the work piece handling had already been streamlined by simply placing the parts mounted to a special fixture on a magnetic plate in the work bowl where they are electro-magnetically clamped. With the VG systems, this renowned manufacturer implemented further significant functional and technical improvements.
However, the grinding medium, a mix of aluminum oxide and water, proved to be quite a challenge for the Trowal engineers. Because of its high abrasiveness, aluminum oxide is an excellent deburring medium but, at the same time, it can cause considerable wear on all machine components exposed to it during the finishing process, like for example, pump piping and hose connections. To minimize the wear rate when pumping the corundum/water slurry, highly wear-resistant materials and a special peristaltic pump are utilized.
After a raw work piece is placed onto the magnetic plate, the work bowl is flooded with water. Then the media/water slurry is pumped from a storage tank into the work bowl. Upon completion of the finishing process the slurry is pumped back into the storage tank. For removal of any residual abrasive particles from the work piece surface, the system is flooded with clean process water.

Technical highlights:

The work bowl of the multi vibrators, model range MV and VG, is equipped with an integrated magnetic plate. The work pieces, mounted onto a special fixture, are placed on this magnetic plate and held in a stationary position with an electromagnetic clamping device. This causes the clamped parts to vibrate at the same frequency as the work bowl, generating a very fast relative movement between the work pieces and the grinding media and producing an intensive but, at the same time, gentle deburring/grinding effect. The result: Perfectly deburred and ground surface areas at significantly lower processing times.
At the center of these innovative finishing systems are three high-speed vibratory motors that allow changing their rotational direction and RPM as well as their position. They are running at very high speeds but produce extremely low amplitudes. Since the directional effect of the induced vibrations is overlapping, the MV and VG vibratory systems produce excellent isotropic finishes on complex and/or delicate components, especially on surface areas that cannot be reached with conventional vibratory finishing methods.




Author: Christoph Cruse
For Information:
Walther Trowal GmbH & Co. KG
Rheinische Str. 35-37
42781 Haan, Germany
Tel. +49.2129.571-207
Fax +49.2129.571-225
E-mail: c.cruse@walther-trowal.de
www.walther-trowal.de