Compact continuous feed shot blast machine for small, delicate castings

The compact troughed belt continuous feed shot blast machine THM 300/1 was specifically developed for processing high volumes of small work pieces. It combines the small footprint of batch tumblast machines with the advantages of continuous flow operation. It streamlines and speeds up the blast cleaning processes for small castings.

Continuous troughed belt shot blast machine fits seamlessly into integrated manufacturing processes

Walther Trowal developed the THM 300/1 specifically for small, delicate or thin-walled cast work pieces like, for example, aluminum or zinc die-castings with diagonal dimensions of between 20 and 150 mm (about 0.8 to 6.0”). Work pieces can range from components for toys (model cars and trains) to consumer electronics or furniture parts.

For the first time a shot blast machine for processing small work pieces is available with the footprint of a batch tumble belt machine that permits, however, continuous feed operation. Compared to the smallest THM machines supplied to date by Walther Trowal, the THM 300/1 design is considerably more compact: It requires an area of only 1,4 × 2,7 m (5 x 9 feet) and can, therefore, be easily integrated into existing production lines.

The troughed belt work piece transport system Walther Trowal is utilizing for its continuous shot blast machines is gently guiding the work pieces through the machine in a spiral motion. This ensures that all work piece surface areas are equally exposed to the blast media stream.

With this new machine type Walther Trowal meets the demand from many customers in the foundry industry for a surface treatment system for small components that can be easily integrated into their existing manufacturing lines.

“The THM continuous feed machines with their unique troughed belt work piece transport system are more and more displacing the conventional batch tumble belt machines. Our customers integrate them into interlinked manufacturing processes, which greatly facilitates the material handling. The work pieces are fed into the shot blast machine at the given production rate. The intermediate transport from one process stage to another and intermediate storage are completely eliminated”.

Meik Seidler, Sales manager shot blasting at Walther Trowal

For the new blast system Walther Trowal is using the newly developed WTY turbines with curved throwing blades. Compared to conventional blast turbines they generate a substantially higher throwing speed. This increases the impact energy of the blast media on the work pieces, which in turn helps reduce the processing times.

A communication processor allows integrating the shot blasting operation into higher-level process controls. Explosion protected dust collectors ensure safe operation in line with prevailing explosion prevention standards.

Background information: Gentle work piece transport in the Walther Trowal troughed belt continuous feed shot blast machines

The THM troughed belt continuous shot blast machines from Walther Trowal are equally usable for mass produced bulk parts as well as for delicate individual components with complex shapes. Because of their simplified work piece handling and superior shot blast results they are more and more displacing conventional batch tumble belt machines

These machines are especially advantageous for processing delicate work pieces: The parts in the trough are not colliding with each other from relatively high dropping heights but are passing through the machine with a gentle rolling movement. The transport rods are covered with a polyurethane lining, which further protects the work pieces from getting damaged or nicked. Since there is a technological trend towards more delicate components that must be blast cleaned, the gentle work piece transport through the shot blast machine is especially important. The Walther Trowal troughed belt transport system makes sure that the work pieces are passing through the machine without getting damaged.  

For somewhat larger work pieces with complex shape the troughed belt machine concept also produces better blast cleaning results than spinner hanger shot blast machines: While passing through the trough the work pieces are continuously rotating. This ensures that the blast media is reaching all work piece surface areas with the same intensity, and always from the same distance. The result: All-around highly homogeneous shot blasting results.   

Dipl.-Ing. Meik Seidler
Sales manager massfinishing and shotblasting

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