Tag Archives: polishing

Allgemein

Gentle finishing of extremely hard surfaces

Overlapping rotational work piece movement is the basis for even, all-around surface finishes

Gentle finishing of extremely hard surfaces

The spindles allow the processing of batches of up to 18 work pieces. For this photo different work

At this year“s IMTS Walther Trowal is introducing the new drag finisher M-TMD 6M for treating high-value components that require a first-class surface quality. The new drag machines will place a mirror polish on the hardest materials – even on ceramic components. With these machines the costs for polishing can be reduced to a fraction of the costs for manual surface grinding and polishing. But even more important: They ensure absolutely repeatable, high-quality finishing results within an extremely narrow tolerance band.

Walther Trowal developed these new machines specifically for treating high-value components requiring extremely careful handling for the complete finishing process. For example, they are utilized for finishing the surface of turbine blades, impellers for turbo chargers, precision components for pumps and compressors as well as for orthopedic implants.

The new drag machines of the M-series have a carousel with multiple rotating workstations. In turn each workstation is equipped with spindle heads containing several spindle drives onto which the work pieces are attached with special fixtures. In addition, these machines also contain a stationary work bowl filled with grinding or polishing media. As the work pieces are „dragged“ through the stationary media mass, the simultaneous rotational work piece movement by carousel, workstations and spindles creates different overlapping patterns, which ensure an even and intensive coverage of the complete work piece surface.

Christoph Cruse, director of sales at Walther Trowal, foresees a big demand for these machines at some of his customers who produce delicate, high-value components. He explains: „With our new machines we want to assist the manufacturers of work pieces that must receive the best possible surface finish, and where even the slightest surface flaw or scratch might cause them to be scrapped. Furthermore, we target parts where deviations from the dimensional specifications of a few thousands mm can be a detrimental. The M-TMD drag finishers with their perfect surface coverage open brand-new possibilities for finishing such work pieces.“

Die M-TMD 4 drag finisher is equipped with four work stations and can process 12 parts in one single batch; the M-TMD 6 – with six work stations allows batch sizes of up to 18 pieces.

At this year“s IMTS Walther Trowal also displays a range of mass finishing equipment including rotary vibrators, the MV multi vib vibrators and a high-energy centrifugal disk finishing machine.

One drag finishing success story:
Polishing of the extremely wear resistant ceramic coating on orthopedic implants

One example for the successful use of the new drag finishers is a process, specifically developed by Walther Trowal, for polishing of knee femorals made from a chromium-nickel alloy, which are covered with a ceramic coating applied with a special vapor deposit method. To date these parts had to be finished manually in time consuming multiple steps with the risk of high quality fluctuations.

After a pre-grinding step the ceramic coating is polished in the new M-TMD drag finisher with a polishing medium specifically developed for this application. The result: Although the ceramic coating is extremely hard, the drag finisher produces a very smooth, shiny and highly wear resistant finish from the initially rough surface condition. The new coating extends the fatigue life of the implants from to date about 20 up to 30 years!

In developing this process Walther Trowal took an entirely new approach. Instead of using relatively soft polishing materials the company is adding an extremely hard substance to the polishing medium, namely diamond powder.

Christoph Cruse explains the advantages of the new process as follows: „Soft materials can be polished relatively easily. But the manual polishing of extremely hard coatings has been extremely difficult, especially because an even surface finish is essential for the functionality of the component. In the case of vapor deposit coating, with a layer thickness of just a few microns, it is essential not to remove too much of the coating material from the part surface. With the M-TMD drag finishing technology and the new polishing media we have resolved this difficulty: The finish is absolutely even on the entire surface area of the implants.“

Walther Trowal at the IMTS 2018
September 10 – 15, 2018, Chicago, IL, USA
North Building, Level 3, Booth 236609

The technical details

In standard drag finishers the work pieces are directly mounted to the workstations and „dragged“ through the stationary media bed producing an extremely high processing intensity. This method is more than adequate for most work pieces and produces excellent finishing results.

The new M-TMD systems allow one additional rotational movement, namely that of the spindles mounted to the workstations. The multi-spindle heads on the workstations can be also be angled allowing the adaptation of the media coverage on the work piece surface to different work piece geometries.

All process steps, from cut-down, over surface smoothing to the final polishing, take place in the same machine, without having to remove the work pieces from the spindles.

The new drag finishers are suitable for dry as well as wet processing. In wet processes for cut-down, surface smoothing and, occasionally, for polishing, special finishing compounds are used. For the targeted edge radiusing within a tolerance range of a few thousands mm, like for example for tungsten carbide drill bits or milling tools, dry grinding media are utilized. Dry processing is also used for high gloss polishing with special pastes and polishing media.

Facts about Walther Trowal

For 85 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-sale service like sample processing in one of our demonstration labs and global repair and maintenance service.

Walther Trowal serves many customers in many industries around the world. For example, in the automotive and aerospace industry, medical engineering and wind power generation.

Walther Trowal in America

The recently opened „Tech & Training Centre“ of the Walther Trowal LLC in Grand Rapids, Michigan has, among other equipment, a test lab for the „Trowal Coating“ technology allowing interested customers informing themselves about the most suitable coating method for their work pieces.

Trowal has also extended its presence in Latin America by recently opening a sales office in Mexico, which is, of course, using the knowhow and resources of the Grand Rapids facility.

Company-Contact
Walther Trowal GmbH & Co.KG
Georg Harnau
Rheinische Str. 35-37
42781 Haan, Germany
Phone: +49 2129.571-0
Fax: +49 2129.571-225
E-Mail: info@walther-trowal.de
Url: http://www.walther-trowal.de

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VIP Kommunikation
Regina Reinhardt
Dennewartstraße 25-27
52068 Aachen, Germany
Phone: +49.241.89468-24
Fax: +49.241.89468-44
E-Mail: reinhardt@vip-kommunikation.de
Url: http://www.vip-kommunikation.de

Allgemein

Dengeling more productive than grinding, polishing and shot peening

high-speed hammering of steel surfaces as turbine blades realizes roughness values of just 0,2 µm (Ra) reliable and accurately, dengeling with special machining center: higher productivity than frictional grinding, polishing, shot peening, no rework, upgrade possible.

Dengeling more productive than grinding, polishing and shot peening

High-speed hammering: The Starrag process peening produces a micron-precise final contour.

High-speed hammering demonstration
Rorschacherberg – There was one demonstration at the „Airfoil Technology Days 2014“ in July that attracted a constant stream of visitors. On a machine tool , Starrag was demonstrating the dengeling process that renders any form of finishing of blades unnecessary. A ready to install component is produced in a single clamping.

CNC controlled dengeling achieves lowest roughness
Dengeling is generally a manual method that is particularly widespread in agriculture, where it is used to smooth and sharpen the blades of scythes or sickles by hammering. Instead of a hammer, the Starrag process uses a special electrically powered tool to give a component its final profile with micrometer accuracy in a machining centre. „The dengeling tool essentially behaves in the same way as a normal tool that is fitted and controlled by the CNC,“ explains Product Manager, Michael Koller. „At the Airfoil Technology Days 2014 I used an LX 051 to demonstrate how it can replace polishing.“ The key benefit of the alternative to grinding is that roughness values of just 0.2 micrometer (Ra) can be achieved reliably and repeated accurately.

More precise, more targeted, more controlled than shot peening
During machining, a pulsed impact ball hammers rapidly (up to 600 Hz) and with huge power. Dengeling changes the original structures of the boundary layers on the surface to a depth of 10 mm. Initial practical tests show that the process is more precise, more targeted and more controlled than the widely used shot peening method. „We are currently working flat out to upgrade all of our so-called blade machines – so all the machines in the LX series“, Koller says. This upgrade will enable all turbine blade manufacturers to replace polishing, frictional grinding and shot peening with the dengeling process, thus making massive reductions in their process chain and cycle times. It is incredible how Starrag has used the latest technology to breathe new life into the old-fashioned process of Dengeling.
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The Starrag Group is a world technological leader in the manufacture of precision machine tools for milling, turning, drilling and grinding small, mid-sized and large workpieces in metal and composite materials. Its customers include international corporations operating in the aerospace, transport, industrial and energy markets. Its portfolio of machine tools is supplemented by technical and customer services, which substantially add to customers“ productivity.
Its products are marketed under the following strategic brands: Berthiez, Bumotec, Dörries, Droop+Rein, Heckert, Scharmann, SIP, Starrag, TTL, WMW. The group of companies, with its headquarters in Rorschacherberg, Switzerland, operates production sites in Switzerland, Germany France, the United Kingdom and India, along with sales and servicing companies in many other countries.
The Starrag Group is quoted on the SWX – Swiss Exchange (STGN).

Starrag AG
Dipl.-Ing. Michael Schedler
Seebleichstraße 61
9404 Rorschacherberg
+41 (0) 71 858 8111
info@starrag.com
http://www.starrag.com

rgt redaktionsbüro gerd trommer
Gerd Trommer
Johannishofweg 7
D-64579 Gernsheim
06258 932010
presse@rgt-gg.de
http://www.rgt-gg.de

Allgemein

Walther Trowal significantly reduces non-productive times for deburring of internal part surface areas

Closed loop media handling increases productivity

Walther Trowal significantly reduces non-productive times for deburring of internal part surface areas

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

At METAV 2014 Walther Trowal 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, Walther Trowal 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 Walther Trowal 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.

Lose burs in components used for the operation of complex systems, for example, hydraulic valve blocks for the aerospace industry, can cause system failures with catastrophic consequences. For this reason, such components require careful and complete deburring of all their internal passages.

The Walther Trowal MV finishing systems have 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 Walther Trowal implemented further significant 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 abrasivity 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, pumps piping and hose connections. To minimize the wear rate when pumping the corundum/water slurry Walther Trowal uses highly wear resistant materials and a special peristaltic pump.

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 which 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 which cannot be reached with conventional vibratory finishing methods.
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Facts about Walther Trowal

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-sale 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.

Walther Trowal GmbH & Co.KG
Christoph Cruse
Rheinische Str. 35-37
42781 Haan/Germany
+49 2129.571-231
c.cruse@walther-trowal.de
http://www.walther-trowal.de

VIP-Kommunikation
Regina Reinhardt
Süsterfeldstrasse 83
52072 Aachen/Germany
+49.241.89468-24
reinhardt@vip-kommunikation.de
http://www.vip-kommunikation.de