Grit blasting is a process involving the use of steel grit to blast away surface contaminants from metal, concrete, glass and other materials.
It can be used for both industrial purposes as well as household cleaning. There are many benefits to this type of blasting over traditional methods such as sandblasting or coring because it leaves no residue on the object being cleaned.
The blog post below discusses the science behind grit blasting and how it works.
Introduction to Grit Blasting and Science Behind It
Grit blasting, like all modern abrasive blasting techniques, refers to the use of abrasive material (usually of solid granules) to remove material from a workpiece.
It uses compressed air for propelling the grit, which is then projected against a surface. Grit blasting is a cost-effective and environmentally friendly way to prepare surfaces for coating and assembly.
Grit blasting cleans the surface by mechanically abrading it.
The Science of Grit Blasting
The science behind grit blasting is simple.
It is abrasive material projected on a surface. It is called grit blasting because grits are used to produce sparks.
Thus, the process removes contaminants through abrasive processes. Abrasive materials provide abrading action.
Thus, when the surface of the body is subjected to grit blasting, mechanical abrading takes place. The most commonly used grits are aluminium oxide and silicon carbide among others.
To better understand the science behind it, let us take a deeper look at the grit-blasting process. The grit blast process normally begins with the operator loading a tank with grit and sand.
The sand is to be used later on for the finishing of the objects. The grit is loaded into the blast cabinet or machine.
When the grit and sand are loaded, the blast cabinet is ready to be used. The blast cabinet is fitted with the blasting media.
When the blast cabinet or machine is in action, the grit is propelled by compressed air. The grit is propelled through a nozzle and is projected on the surface of a workpiece.
The extent of the mechanical action on the blasted surface depends on the size of the grit and the distance of the grit blast area. The grit blast machine adjusts the blasting speed to project the grit as far as possible from the surface.
Thus, mechanical abrading takes place. The grit blast machine is an important component of grit blasting.
A grit blaster varies the blasting media used. Some blasters use desiccants to remove moisture on the surface of a workpiece.
The moisture content of the workpiece determines the type of grit to use. If the surface is too dry, the grit is too sharp and results in indents on the surface of the workpiece.
If the surface is too wet, the grit is too soft and results in a smooth surface. A wet surface does not provide the required mechanical abrading action.
Grit blasting equipment can be used on all surfaces such as wood, metal, concrete, brick, glass, fibreglass, and leather. Grit blasting uses compressed air.
Abrasives are placed on a blast nozzle. A grit blast nozzle is a specialised type of air nozzle.
A stream of air passes through a magnetised nozzle, propelling the grit into contact with the workpiece. A grit blaster may use either dry (sand) or wet (salt) grit.
The moisture content of the grit, the application, and the workpiece surface, determines which grit or grit mixture to use. Wet salt grit is used to remove rust from metal.
Dry sand grit is used when a slight rust coating exists on metal. Both types of abrasives are used on other surfaces such as wood, glass, concrete, and brick.
Dry sandblasting grit is made from quartz. Dry sand grit cannot be used on metal.
A pit of sand can be dug which allows sand to be excavated from the bottom and conveyed upward through a pipe. The sand is dried and then painted with a protective coating.
A grinder or crusher is then used to break the dried sand into smaller pieces. The fine powder is then used as a dry abrasive.
Dry sand grit requires that the surface be dry to an extent that the blasted material is not sticky. If the sand becomes wet it loses adhesion to the workpiece surface.
So there we have it, we have looked in-depth at how the process works as well as understand some of the science behind it.
Materials That Can Be Cleaned With Grit Blasting
Grit blasting can be used on all kinds of materials for all sorts of purposes from minor to major work.
Different abrasive grits are used depending on the type of material being blasted, whether it’s metal, plastic, glass, or stone. Each type of grit is suited to a particular task, and each grit has an optimal size to be made with the most efficient use on friction and with the most power.
Abrasive materials produced by grit blasting are classified as dry bulk material or wet bulk material. Wet blasting is done in a tank of water, and is considered more effective for heavier substances.
Dry bulk blasting is an effective, albeit slower, process, and is often used for finer tasks.
List of the Benefits of Grit Blasting
Some benefits of grit blasting include:
- Minimises the amount of labour required.
- Less labour-intensive than other techniques.
- Quicker and easier to achieve desired results than other techniques.
- Reduces downtime.
- Less tiring.
Grit blasting services are available in many different forms.
We’ve only scratched the surface of what grit blasting can do for you, but if it sounds like your next project needs a little more than just steel grit and baking soda (or sand), contact us to see how we can help you.