Walther Trowal offers a new generation of blast turbines for troughed belt continuous feed shot blast machines, type THM. These turbines increase the throwing speed and, thus, reduce cycle times for shot blasting of light metals such as aluminum and magnesium.
For weight reasons, these two metals are increasingly replacing steel components. However, shot blast applications for aluminum and magnesium frequently require soft, less abrasive blast media, for example, aluminum shot.
"When it comes to shot blasting die castings or forged components made from aluminum, magnesium and zinc, many users are switching to somewhat softer aluminum blast media," said a company spokesperson. "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 and improved surface finishes."
The throwing blades in the new turbines are curved on both sides, allowing the turbines to run in two directions.
For applications requiring steel and stainless steel blast media, Walther Trowal offers curved throwing blades in wear-resistant tool steel. This increases the overall blade uptimes. Existing THM machines can be equipped with the curved blade turbines.
"THM continuous troughed belt machines can handle large quantities of bulk-produced small parts as well as large, delicate single workpieces with complex shapes," said the spokesperson. "Because of the simpler and gentler workpiece handling, they frequently replace conventional batch tumblast machines.
"THM continuous feed machines are especially advantageous for treating very delicate components. Unlike 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 workpieces are spread throughout the length of the trough, ensuring a gentle, nick-free processing. The workpieces gently roll 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, THM continuous shot blast systems also offer advantages. Because the workpieces gently tumble through the tunnel formed by the troughed belt, they are exposed to the blast stream from all sides, with the distance between workpieces and turbines remaining constant. This ensures all around, perfect shot blasting results."
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.
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 not only has a low weight, but also offers high tensile strength.
"For shot blasting of these materials in THM machines, aluminum media is becoming quite popular," said the spokesperson. "Since the distance between the blast turbines and the workpieces is very small, the shot blast process is highly effective, even though the blast media has a low bulk density."
For more information contact:
Walther Trowal LLC
4540 East Paris Ave. SE, Suite F
Grand Rapids, MI 49512
616-455-8940
www.walther-trowal.com