In blasting it is the abrasive in use that is giving the surface finish. The size grading of the abrasive is, therefore, paramount in achieving cleaning eficiency and, where appropriate, a suitable finish for coating.
When using metallic abrasives these are recycled within the operation, the particles wearing down gradually as they are used. The abrasive forms an operating mix (or "working mix") which contains a range of abrasive sizes.
Metabrasive Ltd., the UK's leading manufacturer and supplier of metallic abrasives, has developed the "Blastcheck Kit" to enable abrasive users to check and control the size grading of the abrasive in circulation within a blast machine. The "Blastcheck Kit"
is easy and simple to use and contains all the equipment necessary to give an accurate size grading of the abrasive operating mix (e.g. a sampler, a set of sieves, and measuring cylinder). Also included is a pocket microscope for checking coverage and surface cleanliness and a computer programme customised to the user's individual application. This shows the results in graphic form and prompts corrective actions in response to the results obtained.
As well as producing the required surface finish, it is imperative that a balanced
size grading is maintained to ensure the most cost effective blasting operation. A
coarse size grading, as well as leading to a rougher surface finish, gives lower
productivity due to a lack of coverage of the full surface. Too fine a size grading
gives lower productivity as it lacks the impact to remove all contaminants from the
surface.
As well as the size grading the cleanliness of the abrasive mix itself is important,
especially in maximising wheel component life, and the "Blastcheck Kit"
enables abrasive users to check for retained waste in the abrasive mix. As little as
1% of non- metallic waste in an abrasive mix can halve the life of wheel blades in a
wheel machine or nozzles etc. in air blasting.
