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Imperial
S.r.l.
Via Giovanni Amendola, 29
46028 Sermide (MN) - Italy Tel. +39 0386 61184
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The production of flexible abrasive products |
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Flexible abrasives are used in a wide range of applications; they are used in working with wood, metals, synthetic materials, paints, marbles, rubber, leather, glass, and all surfaces that must be smoothed and polished for technical or aesthetic purposes.
For best results in each of these specific fields of applications, the appropriate equipment is needed to produce the flexible abrasive product.
The following raw materials are mainly used in producing abrasive products: backing: paper, cloth, paper + cloth; adhesives: animal glues (from skin or bone), phenol resins, ureic resins, alkyd resin, epoxy resins; abrasive: silicon carbide (Sic), corundum (AL2 O3); additives: excipients, colorants, softeners, solvents, plastifiers, hardeners, drying agents.
The main production stages for flexible abrasives may be summarized as follows:
First spread of binder on the backing: this is done by immersing cylinders in a tank containing the glue/resin. The gluing machine is supervised by continually checking the weight using radioactive beams.
Spreading the abrasive grains: during this stage, the abrasive grains are drawn to the backing strip by means of an electrostatic field, having a variable voltage and distance depending on the size of the grains and the speed of the strip.
First glue drying: drying takes place in large ovens, with the product arranged in rows on rods. The abrasive strip is moved slowly forward, hanging from the rods. The position and distance between the rods depend on the drying capacity and unloading speed of the oven.
Second binder coat: the second coat of binder, spread over the glued grains provides a definitive anchor. As for the first glue, cylinders are used to spread the binder.
Second glue drying: same procedure as described in point 3, using longer ovens
Polymerization: this additional stage of the production process involves only those products using resin as a binder. It is carried out by blowing hot air through reels of product, to harden the resin film.
Flexibilizing: called "flexibilizing". The product is moved over small cylinders, to break the layer of binder into strips whose width depends on the diameter of the cylinder.
Stearating: this step has the unfinished jumbo abrasive spread with baths of calcium or zinc stearate to lubricate it, making it less likely to jam up with dust from the processed materials. This stage is used only for some types of products requiring this step due to their intended application.
Packaging: the unfinished abrasive strip is cut into lengths, squares, disks or sheets by cutting or chopping machines.
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The material supporting the abrasive grain Is its backing. The grain is attached to this backing by means of a binder.
- Paper backings come in different types and weights;
- Cloth backings with a base of cotton or polyester can be permeable to water or else waterproof.
 
The binder
The binder most used is composed of artificial resins, and in other cases hide glue.
In general, the abrasive material is attached to the backing with two layers of binder, i.e., one to support, the other to fix.
Structure of the abrasive products is as follows::
- Backing
- Make coat
- Grain
- Size coat
Spreading the abrasive material (grain) and relative method
The abrasive material (grain) is spread by means of an electrostatic process.
The abrasive material’s backing (paper or cloth) is coated with the make coat (glue or resin) and put into motion.
It passes at a certain distance above the conveyor belt
containing the grain.
The grain is attracted to the conveyor belt due to the electrostatic field from above, and is deposited onto the size coat.
This method allows the grain to be directed in a certain way so that the longitudinal axis of the grain is arranged at a right angle on the backing.
This method of spreading the abrasive material ensures that the grain is deposited evenly on the backing.
This results in an excellent sanding quality, while favouring a notable abrasive capacity.
Structure of abrasives on paper or cloth backing
Products from the IMPERIAL Company are manufactured using advanced techniques.
Their prominent features ensure an excellent abrasive capacity, durability, ease of use and an excellent quality of the sanded surface.
 Grana abrasiva E' un elemento di taglio vero e proprio. IMPERIAL utilizza svariati generi di grana, prodotti sinteticamente:
This is a true cutting instrument. IMPERIAL uses different types of grain produced synth-etically
- Aluminum oxide with a hardness of 8.5, wedgeshaped, very sharp and adaptable.
- Silicon carbide with a hardness of 9.4, wedgeshaped, very sharp and fragile.
Hardness is defined accord-ing to the Mohs scale, where the hardest material is diamond (10). |
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