Metal oxidates and corrodes over time. Metal blasting/peening is a method that applied by a proper blasting machine for remove lubricant, soil, filth, dirt, rust and corrosion on the metal. Prepares the metal to be paint. Paint process prolongs metal’s life.

Blasting procedure is applied by special production abrasive by name grit. Metal blasting both removes rust and corrosion which are visible or in micronized dimensions on the metal and reveals extract of the metal.

A metal blasted freshly is unguarded to rust and corrosion. After metal blasting procedure if the metal leaves humid envoriment it is seen that it is oxidized in a few hours and oxidation manifests itself with change of color. Therefore blasted metal has to be protected as soon as possible, has to be painted and contact with air of metal has to be prevented.  The best application is zinc painted.

Aim of blasting procedure is to clean the metal that will be painted properly by proper machine firstly and create pores and roughness. In this way, pint can hold on to metal surface. Blasting procedure provide roughness as in sand paper.  It is imposible that applied paint can’t stick on the metal surface by any chemical reaction. For absolute  sticking surface has to be roughened by proper abrasives.

The main difference is that in the shot blasting process we use throwing wheel and in sand blasting process compressed air is used.

Shot blasting: Abrasive gets accelaration through the throwing wheel, which is rapidly turning in a special steel housing, with one side oriented opening. Shot blasting is used for blasting metal, different profiles and welded constructions.

Sand blasting: Abrasive is dosed into the stream of compressed air and gets a real acceleration in the outflow from the blasting nozzle. Sandblasting is used in the blasting rooms, blast cabinets, pressurized portable sandblasting machines, vacuumed sandblasting machines.

For blasting machines various blasting abrasives are used. These abrasives can be metal base, glass and mineral base. It is very important that to choose right abrasive. For all sorts of blasting machines, types of abrasives that will be used are different. Stainless steel ball, glass bead, aluminium oxide ball, steel grits, basalt,  silica, quartz are used as abrasive.  

Silica: There is quite thin types of silica. Generally, silica is used for thin sheet metal in order to light blasting.

Basalt: Dust emmision of basat is low and this abrasive is used at indoors and it is used in the place where the abrasive can be rcyled.

Grit: Dust emmission of grit is low and power of blasting of grit is the best. Actually, it is not sand it is iron wastes.

SURFACE CLEANING VALUES

Surface cleaning values are evauated according to ISO 8501-1:1998 ve TSE EN ISO 8501-1 standarts.

According to ISO 8501-1 surface cleaning values as follows.

Sa 1 < 80% Light cleaned

Sa 2 80% Well cleaned

Sa 2.5 96% Very well cleaned

Sa 3 99% Complete cleaned

Blasting is a surface treatment method that is based on blasting or throw the particles (abrasive) on the workpiece surface at high speed by sandblasting/shot blasting machine. This process known as scraping at ship building industry, shot or shot cleaning (peening) at other many industries and this process is used for different purposes from various metals to glass, from beton to fabric and from steel ball to granulated glass, from silica sand to apricot seed  many different abrasive materials are used. Shortly, sandblasting/shotblasting machine can be described thus; sandblasting/shot blasting machine is the machine that provides to throw the particles (abrasive materials) that are used for blasting to the preferred surface at high speed.  Many sandblasting/shot blasting machines contain additional equipments and workpiece carrying systems along abrasive blasting process. Additional equipments make prepared the flung particles (abrasive materials) which are collected and cleaned due to be thrown again (recylng). Workpiece carrying systems provide the hitting of the abrasive to the workpiece in proper angle and proper speed. There are 2 key features while sandblasting/shot blasting machine is designing.      

All sandblasters work on roughly the same principles: finely ground silica sand is used to clean and abrade a surface, typically metal, of any rust, paint or other unwanted surface materials. This is done by means of an air-powered pressure gun that fires out the sand at high velocity to impact with the intended surface. All sandblasters use said pressurized gun, which has a ceramic barrel or interior coating to prevent the sand from eroding it over time. The exact process by which the sand is introduced to the gun differs. Basically speaking, there are three types of sandblaster.

The first of the three types of sandblaster is the gravity-fed model. There are three basic parts to this model: an air compressor or pressurized air tank, a hand-held pressure gun with air hose and a hopper on top of the gun. The hose connects to the air tank, and the hopper is filled with silica sand. When the trigger of the gun is depressed two things happen. First, compressed air fires through the gun as long as the trigger is held down. Second, an opening at the top of the gun into which the hopper is connected opens. The air flowing through the gun and the force of gravity pulls the sand down through the gun and out the barrel.

Pressure blasters are more often used by commercial organizations, as they are significantly easier to use than the other models but also cost more to use. They consist of a large canister containing silica sand under high pressure. This is a bit similar to the concept behind an aerosol can. A sandblasting gun, usually a two-handed model, is connected to the port at the top of the canister by means of a specialized hose that can withstand the abrading affects of the sand. When the trigger of the gun is pulled, both the air and sand are forced out as a single entity. This means cleanup and maintenance is practically nonexistent, but there are some drawbacks. Because the canisters are fully enclosed, the sand that they fire out cannot be collected and reused. Also when the canister is empty, it must be swapped out for another, or an entirely new one must be purchased, both at significant cost.

A siphon sandblaster is the model you're most likely to find in any handyman's possession. It can be used to clean and strip large surfaces and is moderately cheap. It consists of three parts. It has a sandblasting gun with two separate hoses, one connected to the bottom of the handle and the other connected the underside of the barrel. It has a normal pressurized tank or air compressor. It also has a reservoir of loose sand. This takes the form of a large bucket or container of some kind. The air hose of the gun is connected to the compressor, while the other hose is connected to the underside of the separate sand reservoir. When the gun is fired, the air serves to create a suction, which pulls the sand from the reservoir up the hose and into the gun to be fired out the barrel. As a result of this system, the sand that is fired out the barrel can be collected and placed back in the reservoir to be reused again and again.

 

Sandblasting has a longer history than you might expect. The absolute furthest it can be traced back is 1870, when Benjamin Tilghman invented a machine for paint and rust removal. Of course, this was primitive and rudimentary, but it set the framework for future improvements. Then, Thomas Pangborn took Tilghman’s initial idea and ran with it, adding compressed air in 1904. Another substantial innovation took place in 1918, when the first enclosure was built. This enclosure contained a clear screen for sandblasters to surround the worksite and prevent dust from hitting workers’ faces.By the 1930s, sandblasting was well-known in manufacturing fields. However, despite plant managers’ knowledge of the process, the majority felt the method was too messy. A change in attitude about sandblasting occurred when the U.S. Navy needed more efficient ways to prolong the service life of their coating systems. After simple scraping and sanding did not bring about satisfactory results, the Navy attempted sandblasting. Upon completion, the Navy realized that sandblasting was necessary for proper adhesion and performance of the coating system they would apply. Hence, this successful project set the foundation for the protective coating industry and numerous future success stories. Sandblasting has evolved significantly, becoming safer and causing fewer cases of the lung disease silicosis. As sandblasting has emerged, so has blasting, in general, as a restoration practice for a variety of surfaces. More sustainable processes such as sodablasting and vapor blasting have become available as potential options and better substitutes.