Anti-static punched brushes
Often in production processes that handle non-conductive films or workpieces, an electrostatic charge is induced that then prevents the work cycle from running properly. In such cases, antistatic brushes can be used to eliminate surface charge. For example, this can be useful to remove dust from a film or to drain a surface before painting, avoiding defects on the final product.
The basis of operation is the ‘tip effect’. If the filament is electrically conductive, each end of it is capable of attracting charges from the surface to be treated. It is then necessary to ground the brush body, which is also conductive, in order to keep the potential of the discharge system at zero. The filament is therefore essential to the efficiency of the anti-static brush. It must be conductive and very thin, so that there are many discharge points. We mainly use Thunderon, which has a number of advantages over the carbon fibre that is traditionally used. Sometimes other filaments are used, e.g. at high temperatures very fine brass is used. The most efficient condition is achieved by leaving a distance of about 2 mm between the filament and the surface.
However, by using Thunderon, it is possible to act directly on the workpiece and also achieve a brushing effect!Compared to carbon fibre, Thunderon has several advantages:
- carbon fibre has no consistency, whereas the Thunderon can brush the parts;
- by mixing Thunderon and nylon, any desired hardness can be achieved;
- while carbon fibre brushes are only available in linear form, with the Thunderon it is possible to construct brushes in any shape, even rollers.
Our standard, called SAB-1000, is D=20, H=27 and L=1000. Other L sizes can be supplied to order. SAB-1000 is a brush that, due to the materials used, the accuracy of manufacture and the finish, is especially suitable for use in high-tech plants where excellent discharge efficiency is required. For other less complex cases, we offer the SAT-1000, in which the filament is still Thunderon and the brush body consists of a 5×30 mm aluminium strip L=1000.
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The special feature of the brush is that the work surface is made up of millions of individual elements, which are the ends of the individual filaments.
This gives the brush an adaptability that no other element, however deformable, can have.
It depends on various factors. In a nutshell, it can be said that 2 mm is a good compromise. The important thing is that the filaments of the brush work “at the tip” and not on the side.
Depending on the materials used and the dimensions, there is a tensile limit load that a single bunch can withstand.
Beyond this limit the bunch comes off, therefore the brush must be calculated according to the use. This limit can be greatly increased by building “sewn” or “tied” brushes by hand, where a continuous steel wire is placed instead of a single anchor element.
There is no single answer. Speaking for example of cylindrical brushes, the strip brush is generally cheaper when dimensions are important (e.g. over one meter in length). For small dimensions, punched brushes are certainly more suitable and convenient.
It can only happen if the brush has a manufacturing defect, like any other type of object (e.g. a roller made with silicone flakes, one of which is defective and breaks).
When it is important that no contamination occurs, it is advisable to use synthetic (non-natural) fibers with a diameter greater than or equal to 0.15 mm.
Virtually all degrees of hardness can be had, from very soft to very hard. In fact, the hardness is given by the combination between the diameter of the filament, its free length and the density of the bunches.
Of course, we can provide FDA or FOOD GRADE certifications and filament traceability.
Unfortunately not, as it is the machine + brush assembly that must be ATEX certified, not just the brush.
It is however possible to provide the materials that the certifier requires, eg. conductive bases, conductive filaments etc …
Generally speaking it is possible, but it is necessary to evaluate if it is economically convenient, and it is not always. Furthermore, in the case of a punched brush, it is not advisable to regenerate the brush more than twice in order not to reduce the holding of the bunches.