The sandblasting process is an indispensable step in many activities related to the mechanical industry. In the final phase of preparation of a metal object it is necessary to remove impurities or to give particular characteristics to the surface of the treated object to make it suitable for painting or for various surface treatments. These operations disperse large quantities of sand in the working environment and leave residues in the interstices of the processed products.
DU-PUY, which has always been attentive to the needs of the sector, has developed a range of powerful industrial vacuum cleaners, equipped with side channel turbine or high-performance lobe pumps, specialized in the removal and recovery of abrasives from work cabins and cracks of products subject to sandblasting.
The Sandblasting process
In detail, sandblasting is a process that allows you to smooth, polish and clean the surface of a material by eroding the surface layer. This mechanical process is carried out by abrasion caused by a jet of air and sand which must then be removed by suction and in some cases could be reused in the next process.
It’s a pretty quick process considering the standards of mechanics, but it can be slow in the presence of more resistant materials to remove. In these cases you can intervene by decreasing the size of the nozzle to focus more on the jet or choose a different size or type of abrasive.
The sands and grits
The most commonly used abrasives are:
Glass or ceramic microspheres
White or Red-Brown corundum
Granules of plastic
Metal grit or stainless steel
The standard size of the sandblasting abrasive varies between 1.5 mm and 0.250 mm. This varies depending on the type of object to work that is normally metal or steel and in some cases can also be cast iron, timber, ceramic or marble.
Types of sandblasting
Sandblasting can be divided into two methods:
· Conventional or free-jet sandblasting, consisting of a tank in which the abrasive is put into pressure and then be launched thanks to the jet of compressed air. There are no measures to reduce the dangers generated by the production of dust or for the recovery of the abrasive material.
· Sandblasting with closed cycle, or rather with equipment for the transport and recovery of sand, which can take place in:
o Cabin with manual control,with the operator placed outside to direct the jet through guns, without release of dust in the working environment.
o Tunnel shot blasting machine, able to adapt to objects with different shapes and suitable for the treatment of medium and large pieces.
In closed-loop sandblasting, the workpieces are inserted manually inside the machine by the operator, if they are small pieces, or with the help of the crane for large pieces. To avoid the dispersion of dust in the environment the machine cannot operate if the tailgate is not completely closed.
Existing regulations: what they foresee
Once the machining is finished and the machined pieces are extracted, it will be the duty of the operator to ensure the extraction of abrasive residues on the manufactured products or deposited inside and outside the machine. The safety standards at work in fact establish the impossibility of blowing the products coming out of sandblasting with common air compressors to avoid the dispersion of dust in the environment and the throwing of grits towards people. Dust can cause respiratory and/or dermatological diseases due to inhalation and contact respectively. The risks are particularly high when working with abrasives that contain harmful substances, such as silica. In the same way, the grains that are blown with compressed air are launched at high speed with the risk of hitting people, tearing their tissues and wounding them.
The suction must therefore be carried out by means of industrial vacuum cleaners with high vacuum values, able to remove sand with a high specific weight. The M series is designed to ensure the best performance in sandblasting processes.
Industrial vacuum cleaners to speed up your work
M 50 HP
In particular, DU-PUY has developed a double-stage side channel blower suction solution, entirely in aluminium, with double rotor, implemented in the M50 HP model. This feature allows you to greatly increase the vacuum generated by keeping the size small. The aspirator is thus equipped with 4.3 kW of power, combined with a maximum depression of 5.100mm/H2O and dimensions contained in just cm 120x65x180h. Inside the suction chamber there is a replaceable reinforcement belt, to prevent the grit from consuming the chamber itself.
As standard it includes a star filter with surface 20.000cm2 in filtering class L, but on request it is available (in picture) an effective filtration system (PN) consists of large surface cartridge filters with an innovative automatic cleaning system. Particularly suitable for the extraction of grains and very fine powders.
To ensure greater ease of use, and simplify disposal procedures in sandblasting using metal grits, a system of discharge with butterfly valve has been designed that allows to empty the material sucked without any effort.
The range of medium-power vacuum cleaners is flanked by a machine of extremely small dimensions such as the W3 HP, with 3 powerful single-phase 3-stage motors capable of developing 3.9 kW of power and 3.600mm/H2O of maximum depression. The suitable solution for the sporadic suction of small amounts of residues and dust in conventional sandblasting with low budget.
SILOFILTER and CVAC
Our range of vacuum cleaners dedicated to this sector is particularly powerful and complete, suitable for standard situations for small and large companies.
In the case of large plants, where there is a need for automatic suction and discharge of large volumes of grit, DU-PUY intervenes with centralized suction systems to SILOS connected to high vacuum suction units cut to the needs of the customer.