Corundum, both white and brown, is the most commonly used industrial abrasive for surface treatment. Corundum is composed of electro-fused aluminum oxides, with an alpha alumina structure and Knoop hardnesses between 2000-2100 Kg/mm2.
There are several varieties or types, but the most commonly used are white corundum, which is of greater purity and hardness, and brown corundum, which has small percentages of titanium oxide and iron oxide in its chemical composition, which give it its color.
Coniex markets high quality corundum for application by spraying (shot blasting), although the application is also known as sandblasting. The corundum can be sprayed by means of compressed air impulsion, either by Venturi (or suction) or direct pressure.
Its most common and common applications, although not the only ones, are:
- Stripping of surfaces with oxide or paint residues
- Deburring of steel surfaces
- Preparation to coatings such as paint or galvanic coatings
- Preparation to improve rubber-to-metal anchorage type bonding
- Engraving on stone, marble, granite, etc.
- Satin finishing of glass, metals, plastics, etc.
- Finishing of castings.
- Correction of defects in parts.
Its use in sanding charts, grinding wheels, vibration chips and compressed air blasting makes it a very common abrasive in the metal industry.
The most common equipment for blasting with white or brown corundum is as follows:
- Manual suction and pressure blasting booths.
- Portable sandblasters.
- Blasting rooms.
- Dry and wet blasting machines.
- Shot blasting machines with compressed air gun.
Manufacture of corundum
Corundum is subject to international sieving standards by organizations such as FEPA (Federation of the European Producers of Abrasives), or its American equivalent, ANSI.
These sieves are used to identify the particle size of the abrasive.
Their chemical composition varies depending on the origin and production process of each manufacturer. These variants condition the characteristics and behavior of the material, in some cases in a very notable way, especially with regard to its toughness, which colloquially could be defined as its resistance to splitting.
Coniex markets white and brown corundum from 14 grit to 280 grit. The product is delivered in 25kg bags, 250kg pallets or 1000 kg pallets.
Do not hesitate to request a corundum offer and consult with our specialists to determine which type of abrasive is the most suitable for your job.
Corundum for blasting applications
It is important to define the essential characteristics of corundum blasting processes and the requirements to be met by surface treatment equipment that uses this product as an abrasive medium.
The first issue to consider, before the application of this material in a blasting process, is that it presents a great hardness and abrasiveness due to its irregular prismatic shape, i.e., it has sharp edges in indeterminate number.
This characteristic makes corundum, white or brown, ideal for some applications, among which the following stand out:
- Creation of roughness for coatings, anchoring, etc…
- Engraving on metal, stones, glass, etc…
But these same characteristics make it necessary to reflect on the equipment and components to be used for its projection:
- Nozzles, bores, injectors, pipes, etc. must be highly resistant to abrasion and their metal parts (nozzles, bores, etc.) must be made of tungsten or ceramic materials (usually boron carbide).
- Rubber piping should be of high abrasion resistance (preferably sandwiched with nylon mesh).
- The parts exposed to the effect of the jet or the most intense rebound shall be made of manganese steel or Ni hard alloys.
It should be noted that its abrasiveness is such that it is not possible to use this abrasive in machines driven by turbines (shot blasting machines), since the consumption it would generate in terms of drive and regulation elements (blades, spinners, regulators, distributors, etc.) would make it economically unfeasible. Even other elements, such as the collectors, buckets, etc., would be compromised in terms of their useful life.
On the other hand, we must also take into account its high degree of fractionation, which logically translates directly into the generation of residual dust. Therefore, we must have a good selection system (cyclones as a minimum) and an abundant suction, not so much in capacity or depression, but rather in filtering surface.
In the most demanding applications of corundum, such as the creation of controlled roughness, screening systems should include screening towers with stainless steel sieves or meshes.
It is important to point out that whenever non-ferrous surfaces are blasted; stainless steel of different qualities, aluminum, titanium, etc., it is advisable to use white corundum due to its purity and absence of iron oxides.
Consult with our blasting and shot blasting consultants to determine which abrasive is best suited for your job and the equipment that will make your activity more profitable.