Walther Trowal: Aluminum components require soft, less abrasive blast media
Shot blasting of non-ferrous light metal components, which to date were manufactured from steel / New blast turbines with curved throwing blades reduce cycle times
When it comes to shot blasting die-castings or forged components made from aluminum and magnesium, but also zinc, many users are switching to somewhat softer aluminum blast media. Yet, because of their lower bulk density the impact energy of these media is significantly lower compared to other media like steel shot. For this reason, Walther Trowal recently developed turbines with curved throwing blades, which generate significantly higher throwing speeds.
In addition to higher throwing speeds, the new turbines also allow a much higher media throughput. Despite the lower media bulk weight of these “soft” blast media the results are shorter cycle times an, at the same time, greatly improved surface finishes.
Since the throwing blades in the new turbines are curved on both sides, the turbines can be run in two directions.
For applications requiring steel and stainless steel blast media, Walther Trowal offers the curved throwing blades in wear resistant tool steel. This increases the overall blade uptimes significantly.
The first machine equipped with the new turbines will be delivered to a customer shortly. Of course, existing THM machines can be easily equipped with the curved blade turbines allowing the users to increase productivity and reduce their costs.
Walther Trowal at the Aluminium 2016 trade show (Dusseldorf/Germany, November 29 – December 1, 2016): Hall 12 / Booth G 50
Background: Troughed belt continuous feed shot blast machines: Extremely gentle work piece transport
The THM continuous troughed belt machines can handle large quantities of bulk produced small parts as well as large, delicate single work pieces with complex shapes. Because of the much simpler and gentler work piece handling they frequently replace conventional batch tumblast machines.
THM continuous feed machines are especially advantageous for treating very delicate components: Contrary to batch tumblast systems, where the parts are intensively tumbling over each other with a high risk of nicking, in the Walther Trowal THM machines the work pieces are spread out throughout the length of the trough, ensuring a gentle, nick-free processing. The work pieces are gently rolling over the transport rods coated with polyurethane. This gentle part transport is especially important for complex, thin-walled components requiring an intensive blast cleaning process. The results are perfectly cleaned parts without any nicking or other damage.
Compared to spinner hanger machines the THM continuous shot blast systems also offer significant technical advantages. Because the work pieces are gently tumbling through the tunnel formed by the troughed belt, they are exposed to the blast stream from all sides, with the distance between work pieces and turbines remaining constant. This ensures all around, perfect shot blasting results.
Aluminum: The gentle blast media
The blast cleaning and de-flashing of die-cast or forged aluminum components requires soft blast media. Typical forged parts are steering knuckles or swivel bearings. Aluminum die-castings processed in THM systems can be housings, covers, caps and levers.
But there is also an increasing trend towards utilizing magnesium die-castings, especially in the automobile industry. Many structural components, for example dashboard mountings, are made from magnesium. This material has not only a low weight, but also offers high tensile strength.
For shot blasting of these materials in THM machines aluminum media is becoming quite popular. Since the distance between the blast turbines and the work pieces is very small, the shot blast process is highly effective, even though the blast media has a low bulk density.
Walther Trowal GmbH & Co. KG
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.