Blasting of Aluminum – Business as usual?
Only those who deal with the material can offer good solutions – this is an old wisdom from surface technology – it also applies for aluminum. AGTOS builds shot blast machines for cleaning, deburring and finishing. It is obvious that the subject of aluminum has become more and more present and therefore also aluminum as workpieces. Aluminum die casting should be mentioned here in particular.
It is also interesting to use aluminum as a blasting abrasive, treating the workpieces within the blasting machine. One reason for aluminum abrasive is the further processing of the workpieces. If hard blasting abrasive, such as e.g. stainless steel abrasive, stays in places that are difficult to access, this can cause damages to tools during further processing. This is one of the reasons why aluminum abrasive is often chosen for the non-ferritic blasting. In addition, surfaces treated with aluminum abrasive appear mostly more appealing – an effect which is often used in the automotive industry.
On that account, the engineers and technicians at AGTOS have intensively dealt with the topic of aluminum. Numerous tests have been conducted in cooperation with customers. Even machines specially constructed for this material have been developed. Many experiences were gained in the AGTOS test center as well as in practice with well-known customers. Consequently, sophisticated solutions for the blasting of and with aluminum are offered.
Construction of the machine
Increasingly, aluminum workpieces are also treated with blasting abrasive of the same material. This can provide advantages, but has an impact on the construction of the machine.
Due to the physical properties, such as, e.g. the specific weight which is lower in comparison to steel abrasive, special considerations have to be taken into account when constructing shot blast machines. This starts with the repose angle, which affects some components of the shot blast machine, e.g. hopper and bunker. The volume of certain components have to be adjusted as well.
The optimization of the turbines must be considered in this case. The special flow behavior of aluminum blasting abrasive must be taken into account. Therefore, the turbines are constructed to work optimally with various aluminum grains. Aluminum blasting abrasive must be handled gently. Increased heat generation within the turbines is avoided because it destroys the aluminum abrasive. This is the only way to achieve a good blasting result within economical operations.
In the case of shot blast machines from AGTOS, the destruction of this valuable “tool” within the shot blast machine is avoided as far as possible without having any effect on the workpiece surface. Abrasive loss is also prevented. This saves valuable material and also helps to reduce operating costs. After the blasting process, a highly efficient blow-off device cleans the workpieces and discharge of the abrasive is prevented. The above-described measures are directed to the economic operation of the shot blast machine with comparably low operating costs.
Preferred shot blast machines
The blasting technology should at best always adapt to the internal material flow. Therefore, wire mesh conveyor blast machines are a machine type frequently requested by automated operators. The main advantage of this type of shot blast machines is that the wire mesh belt enables the blasting from below and above, without having to turn or hang the workpieces manually.
The workpieces which are going to be blasted are placed on a wire mesh belt, via automatic transfer or by a manipulator (in exceptional cases manually), which transports them through the machine.
They first pass through the inlet sluice. This seals the adjoining blasting chamber to the outside. In the blasting chamber, high performance turbines throw the blasting abrasive onto the workpieces at a high speed. The wire mesh belt is constructed in such a way that the workpieces can be blasted at the same time from the top and bottom. After the blasting process, the workpieces are cleaned due to blowing off the remaining abrasive and dust. The dust will be separated due to the supplied filter unit and the blasting abrasive will return to the circuit of the machine.
The AGTOS wire mesh conveyor blast machines are constructed for the heaviest strain. Due to the installed high performance turbines, an optimal covering of the surface is achieved. This is the guarantee for short blasting times and high quality results.
The automatic blasting device installed directly above the turbines ensures that it is only blasted when workpieces are in the blasting area. This minimizes the wear on the shot blast machine. A blow-off device removes the abrasive remaining on the workpieces.
Hanging workpiece transportation
Many companies work with a hanging workpiece transportation within the plant. For this case of operation, AGTOS has developed the continuous overhead rail shot blast machine for the blasting of and with aluminum. Conventional hanger-type blast machines are also available for bag-railway operation.
The blasting process starts with the entry of the hangers loaded with the workpieces into the blasting machine. An inlet sluice seals the blasting chamber to the surrounding. The hangers pass through the blasting chamber, while the turbines impinge them.
After the blasting process, an outlet sluice follows. A blow-off device helps to recover the blasting abrasive. The hangers can now be fed to further processing steps or to the dispatch.
Batch operation
Rubber belt tumble blast machines with a rubber belt or steel mill tumble blast machines with a belt made of steel plates are the solution of processing workpieces, which are moved in containers such as boxes or pallet cages. However, due to the fact that the workpieces always touch each other during the blasting, loading and unloading, these machine types are not used or rarely used for processing (usually thin-walled) aluminum workpieces.
