Punched roller brushes
Punched roller brushes
Generalities
They are the most common type in industry, as they are used in many production processes. They are generally motorised brushes, i.e. equipped with a metal core capable of withstanding considerable torque. However, they can also be supplied without a metal core. The working surface can be continuous, sectoral, helical, conical, shaped according to drawing. For large rollers or rollers rotating at high speed, a dynamic balancing operation is important, which we perform in-house and can provide the customer with a detailed balancing certificate.
The rollers are used for :
- Precision brushes
- Brushes with complex geometric shapes
- Brushes with mixed filaments or alternating sectors of different filaments
- Modular brushes
- Soft and gentle brushes
The bundles are generally radial, but it is possible to give them a transverse tilt, so as to make the brush rotationally asymmetrical.
This can be useful to soften the action of the roller or to prevent the material from moving in the opposite direction to the motion. The angle α cannot generally exceed 30°.
The rollers are almost always motorised. For this, steel brush bodies with hubs, flanges, tongue housings and others are provided.
Sometimes, for technical reasons, rollers are made on a composite body with different materials. Dynamic balancing can only be performed on rollers with a metal body, as they are ‘non-deformable’.
Roller brushes with D1>L are called round brushes.
They can work in small spaces and can be placed side by side on the same shaft until a roll is obtained, but it will not have the same continuity as a single piece.
An important fact to know at the design stage is the rotational speed at which a roller can be driven. This depends not only on the materials, but also on the load on the brush and the filament-surface friction coefficient. We can calculate the acceptable number of revolutions n of the brush with a function ‘f’ of the static and dynamic parameters and check that it is :
n < f (s, Ft, Pm, D1, D2, P) where s = safety factor, which must take into account the type of load appliedFt = resistance of the bundle to tearing [Kg] Pm = bunch weight[gr] P = bunch hole depth [mm].
We are available to provide you with the necessary project data. At high speeds, a sample must in any case be made and tested under safe conditions.
It is important to provide a suitable engine to operate the roller brush. Power consumption varies depending on brush diameter, speed, working length and filament hardness. It is also greatly affected by the pressure exerted on the brush.
It is therefore only possible to establish the power as an average value and as a first approximation. The diagrams shown give the engine power for a brush length of 1000 mm.
For different lengths, the arithmetic proportion is followed.
Rollers of the desired length can be assembled using modules of standard length 100 mm.
The modules are cylinders of various diameters and holes, which have a toothing at both ends that has two functions:
- transmitting motion between two modules
- realise the continuity of the brushing surface even in the seam lines. At the ends of the roller thus composed are two toothed collars with a threaded grub screw that lock the brush.
The brush body is made of PP, and a white version for food use is also available. The brushing surface can be continuous, sectoral or spiral. The number of bundles depends directly on the number of Z teeth, so brushes with different densities are possible, according to the table. Modular rollers have the advantage that they can form brushes of different lengths and are easy to replace and transport. On the other hand, they have a certain limitation in diameters and bundle arrangement. In fact, these parameters are constrained by the characteristics of the brush body, which being obtained by moulding does not allow for all possibilities. In other words, the modular method can replace the traditional one-piece brush only for the standard dimensions shown in the table.
is a brush specially designed for cleaning photovoltaic and solar panels. In fact, it is well known that panels require periodic cleaning to prevent them from reducing their efficiency due to dust of various kinds. Sunny Brush is modular, so that it can be adapted to the various types of panels on the market.
The constitutive elements are:
- aluminium core in 1,000 mm modules
- D=200 mm nylon brush in 100 mm modules
- POM-C joint bushings with threaded inserts
- locking collars and end finishing The modularity allows the user to order a brush of the desired length (even several metres) and to easily assemble it on the roof using simple screws. Other advantages of modularity (both core and brushes) are cost-effectiveness and ease of transport.
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Frequent questions
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.
