in Vol. 16 - November Issue - Year 2015
THM Continuous Tumble Trough Shot Blast Machine For Blasting Of Aluminum And Magnesium Work Parts At GIFA 2015
Parts before and after
Die cast parts in mill
GIFA is the most important trade show for foundry technology in the world. With 78,000 visitors from more than 120 countries, GIFA 2015 in Düsseldorf was massive and delivered expectations. Totally, 2,214 exhibiting companies reported on numerous business transactions with customers from all over the world. Over 20 manufacturers of shot blasting equipment showed their latest technology.
Walther Trowal exhibited the new model of the THM machine. This new THM continuous tumble trough machine is adapted particularly for the shot blasting of aluminum and magnesium die cast parts. The trend in the automotive industry is the replacing of steel components with components made from aluminium and magnesium.
Weight of the cars will need to be reduced in order to reach new 2025 CAFE standard of 54.5 miles per gallon. Any weight reduction of the car body, engine and transmission will increase efficiency and move manufacturers closer to the new CAFE standard. For weight reasons, these two metals continue to replace steel as the material of choice for the production of a wide range of components. Car manufacturers are already working on development of the next generation of aluminium, aluminum alloy and magnesium parts.
Die casting companies know what is ahead for them and how tough it is going to be to manufacture such parts. In the die casting industry, cleaning of casted parts is done with shot blasting machines using stainless steel media. In the THM shot blasting process, aluminum media is used and has proven to be the best blast media choice for blasting automotive parts made from aluminium and magnesium alloys.
Aluminum media advantage over stainless steel media is in the extreme reduction of the operating costs due to the wear rate of the blast wheels and the machine overall, shift to almost zero.
Blast wheels are throwing larger media quantity to achieve the same processing results because of the low weight of the aluminum media. For this reason, the THM engineering team re-engineered the machine, and the THM continuous tumble trough machine can easily process higher media weight volume. During the development of the new THM shot blast machine, the engineering team invented a new electric media dosing system.
The centerpiece of the THM shot blast machine is the revolutionary parts transport device. The very efficient trough-feed system allows the processing of parts of all sizes, irrespective of their geometry, weight, length or fragility. While moving forward, the parts are simultaneously rotating while moving through the blast chamber, insuring optimum coverage by the blast pattern from the blast wheels and preventing nicking, which is so common for batch tumble belt machines.
Travel speed of the parts, blast wheels rpm and all of the rest of the electric motors on THM are controllable via VFD (variable frequency drive) and PLC. THM continuous (in line) feed machines are especially advantageous for treating very delicate components.
The complex thin-walled parts that are going through the blast cleaning process are not tumbling over each other but gently roll over the polyurethane transport rods. Results are perfect, cleaned parts without any nicking or other damage. Because of the L-shaped belt and gentle parts trough roll, this machine cannot be compared to the batch tumble belt, spinner hanger or any other shot blast machine. Parts are gently tumbling through and they are exposed to the blast pattern from all sides and the same constant blasting distance from the blast wheels, producing uniform shot blasting results.
Blast cleaning of die-cast or forged aluminum components as steering links and knuckles requires a relatively soft blast media. Growing trend of the use of aluminum blast media for processing magnesium components is notable. Many structural automotive components are made from magnesium, which has low weight and high strength properties. With providing very high kinetic energy on hitting the processed parts and short blasting distance, the THM machine is the right choice for processing components made from aluminium and magnesium. The THM continuous shot blast machines can be equipped with 2, 3 or 4 blast wheels.
The THM engineering team has paid attention to many details - for example; because a rough surface on the throwing blades would quickly wear down the aluminum blast media, the blades, impeller and control cage are vibratory finished prior to being installed in the blasting wheels. This results in low dust emissions, extremely reduced media consumption, and very high longevity of the blast wheels.
As stated already - operating costs due to the wear rate of the blast wheels and the machine overall, shift to almost zero. 2025 is approaching quickly.