Abrasive blasting has been used for years in metal restoration, as it is an easy and effective way of removing paint and rust. There are many factors which will determine the effectiveness of abrasive blasting. Abrasive blasting replaces manual sanding with sandpaper, wire brushes and chemicals. There are a lot of things to consider when conducting abrasive blasting, and this article will discuss some of these issues.
One of the best things to know about abrasive blasting is that it can save you money. It does this by reducing the time spent sanding an item between 25 to 75 percent. The products used as an abrasive, like sand and even kitty litter, are very cheap to purchase. The most expensive aspect of abrasive blasting is the machines and enclosure needed to do it. You need no special training, and the materials can also be reused.
Abrasive blasting is by far the most effective means of finishing metal. Sanding by hand can take a very long time, and using chemicals can be dangerous. Using abrasive blasting creates a surface that bonds better to paint or plating.
Abrasive Blasting and Pressure
There are essentially 2 types of machines: direct pressure and siphon. Regardless of the machine, pressure is very important. Many people use pressure that is too high and will pit the material. Direct pressure machines use less pressure than a siphon machine, which is around 60 to 90 PSI. The direct pressure machine operates between 15 and 80 PSI. Lower PSI means better control and less warping of thin parts.
Using the Gun
A standard way of abrasive blasting is by using a sandblasting gun. You need to move the gun across the surface in a circular motion. The angle should also be between 60-degrees and 45-degrees for a direct pressure machine and 1 or more feet for a siphon machine. An extreme angle can cause peening to occur. Keep the nozzle of the gun about 6-inches from the material.
An abrasive blasting gun is a fairly simple device. The nozzle is often made from tungsten carbide, as this metal is incredibly strong and will last a long time. Cheaper materials can mean more maintenance work. The air jet is located behind the nozzle, which directs the air. The air jet should be replaced when you have replaced the nozzle several times. The hose should also be replaced often because it will generally become thin as you use the gun. Eventually, the hose will sink in, and the flow of air will be obstructed.
Abrasive blasting can be done using a variety of materials from, glass beads to corn cob grit. Glass beads create texture but can also remove burrs and descale a finish. Grits, like corn, are used for projects that require an aggressive approach. They leave a dull satin finish. Walnut shell grit is used for deflashing heated plastics. It will not damage the original finish of the material.