Practical advice for choosing the right abrasive material depending on the type of application and the surface to be treated
19.12.2017
Steel grit and iron-cast abrasives are by far the most used abrasive materials in any blasting hall. They can be recovered and reused during several working cycles and they tend not to produce relevant amount of dust during application. Due to the fact that steel is a flexible metal, the abrasive will tend to get rounder and rounder during operations therefore being able to be recirculated 25 up to 50 times (depending on the working pressure and the surface to be treated). In principle, the blasting speed decrease when the steel grit gets rounder.
The iron cast abrasives are about 10% cheaper than the steel grit. They represent a usual choice in many blasting halls, as they are able to ensure a plane-cleaned surface when blasting with them. There is an exception: when the surface to be treated is tuff or the layer to be cleaned is too thick. The main advantage of this type of abrasive does not relate to how fast the operation will go, but to the superior level of the finish works. Usually, in case of metal structures it is recommended to use G12 or G17 abrasives. In case that material with higher level of granulation is needed in order to optimally process a metal surface, it means that there is a problem with either the blasting pot or with the blasting nozzle.
Both steel and iron-cast abrasives are recommended in blasting halls with recovery systems and are not supposed to be used for cleaning Aluminum parts, which they can destroy during operation.
Garnet becomes more and more an option in blasting halls due to its versatility. It can be used to clean almost any type of surface. Its fine granulation levels allow it to generate amazing results especially in case of non-ferrous metal alloys. The premium granulations can be used with almost any surface. The blasting speed is higher than in case of using metallic abrasives. They are recommended in blasting halls where there are no complete recovery systems installed in the floor. It can be reused 6 to 10 times (depending on the blasting pressure) and even so it will produce more dust than the metallic abrasives it is still considered to be clean for the environment.
With the help of a separator the dust resulted within the process can be collected. Its quantity will remain relatively reduced even after several working cycles.
Aluminum Oxide is also a relatively non-pollutant abrasive material, which can be used more times than the garnet and which has the capacity to efficiently clean the surfaces. It is also more expensive and therefore not always the first choice in blasting halls.
Glass beads are more used in blasting cabinets and less used in big blasting halls. When applied at low pressure (about 50 psi) they can be recirculated during 10 to 20 working cycles. They are recommended in applications that require a low level of aggressiveness onto the surface to be treated. Therefore the final result is more related to the idea of polishing instead of profiling. They are recommended in the automobile industry, in case of aluminum products or for peening and deburring operations.
Grit is not used in blasting cabinets as it has a very low capacity to be recovered. It produces a lot of dust and needs a proper collector for it. Furthermore, the quality of the finishes is a poor one. It is recommended for outdoor applications, like the ones in the shipbuilding industry.
Plastic abrasives are excellent for sensitive surfaces like those that are to be processed in the aeronautic industry. They could have been recommended for the automobile industry as well, but even so the final results are excellent the overall cost of the operation would be unjustified. Furthermore, for blasting with plastic abrasives one will need the appropriate equipment.
Nutshells and fruit stones are abrasive materials that are more and more used where there is need to gently treat the surface to be processed. They are cheaper than plastic abrasives and generate quality results, but need to be applied with specialized blasting machines.
Stainless steel and iron abrasives are used in blasting halls where big elements are to be processed and in airless applications. They are recommended for blasting iron castings and are not necessarily used for metal structures.
