The durability of metal surfaces, corrosion protection of different surface treatment processes (by painting, sintering or galvanising). However, these processes are only effective if the treated surface is completely clean. The most effective and fastest way to achieve a metal-clean surface is to with granular spray which uses high-pressure compressed air to deliver small particles of different materials to the workpieces to be cleaned. The high-energy impacting particles, due to friction, remove and abrade the surface layer of the material to be cleaned, turning it into a metallic clean.
The most common spreading materials
Grit blasting sand was previously used almost exclusively in the construction of the plant, but due to technological advances and environmental concerns the range of materials used for granulation has been extended.
Today in all cases, the quality and quantity of the spraying material used is determined by the surface to be treated and its material, as different materials and their varying particle sizes have different abrasive effects on the sprayed surface.
Besides corundum and steel grit, crushed glass, ceramics and dry ice are the most common. Steel on the production of and about machining we have written about before, but glass and especially corundum are also very interesting materials. These will be discussed in a little more detail.
Glass
Graded glass beads, usually of a finer grain size very popular in automotive applications for granular spray.
The basic material of glass is amorphous a solid substance with some of the properties of liquids. Glass is notoriously liquid when hot, but when it cools it becomes mechanically solid without crystallising.
Unlike solid crystalline materials, glasses do not have a definite melting point, only their viscosity changes with heating and cooling.
The manufacturing process basically consists of melting, moulding using various technologies and cooling.
Of the nearly 100 000 types of glass, 7-800 are used in industry. High purity silica glass, also known as quartz glass, is the most commonly used glass for ophthalmic lenses.
Corundum
The granulometry used for brown corundum is an artificial substance which has been calcined bauxite produced in an electric arc furnace using reduction melting technology. Normal corundum is a very hard (Knoop 1800/2100, Mohs 9) and extremely stable material, ideal for cleaning and surface roughening of iron and steel surfaces.
As it is iron-free, it can also be used for the granulation of stainless (inox) materials.
The noble found in nature corundum colourless and translucent, but may discolour when exposed to dirt: the red colour is ruby, all other colours are sapphires.
Today, more of it is produced than is available from natural deposits.
In addition to grain spraying, it is used to make gemstones and in the manufacture of components for instruments and watches.
