TYPES OF ABRASIVES UTILIZIED IN BLASTING

Abrasive Blasting Media
Aluminum Oxide is sharp, long-lasting abrasive sandblasting cutting media that can be re-used many times for grit blasting. As an abrasive blasting media, it is harder than most common dry abrasive blast media and will cut even the hardest metals and surfaces. This particular abrasive blasting media comes in a wide range of sizes. Most widely used abrasive grain is sand blast finishing and surface preparation because of its cost, longevity and hardness. …grit powder penetrates and cut even the hardest metals; thus, preparing a surface for painting and/or a coating application.

Corn Cob
Corn Cob is biodegradable blast media that will not etch or warp surface being blasted. Ideal for applications such as wood log homes and thin metals and plastics

Crushed Glass Grit
Crushed Glass Grit is a silica-free consumable abrasive that offers aggressive surface profiling and removal of variety of coatings. Manufactured from 100% recycled bottle glass, Crushed Glass Grit produces a whiter, cleaner finish relative to mineral/slag abrasives.

Glass Beads
Creating a softer, brighter finish than angular abrasives, Glass Beads offer a silica-free option for shot blasting, peening, and honing, cleaning and light debarring. Glass Beads can be recycled up to 30 times.

Steel Shot
Steel Shot is ideal for peening applications to impart a clean, smooth and polished finish. This dense, smooth shot can be used up to 3,000 times producing minimal dust during the blasting process increased compressive strength of the metal. Sheet shot blasting is the most widely used process for cleaning, stripping and improving a metal surface. The grade or size of steel shot will determine the ultimate finish achieved on the surface to the metal. Smaller shot will result in a smoother and more polished surface. Larger shot will clean more aggressively but produce a rougher surface. Since steel shot does use an abrasive process, a minimal amount of dust is created in the blasting process.

Chemical Compounds
A multitude compounds; ranging from Liquid, Powdered Compounds and Finishing Creams. All compounds to achieve a variety of finishes. Cutting and polishing effects; powders contain rust inhibitors and cleaning agents. Creams can vary in abrasive for processes from cutting to pre-polishing and light deburring leaving a high gloss polish.

GLOSSARY OF PROCESSES

Abrasive – is a material, often a mineral , that is used to shape or finish (see metal polishing and wood finishing ) a work piece through rubbing which leads to part of the work piece being worn away. While finishing a material often means polishing it to gain a smooth, reflective surface it can also involve roughening as in satin, matte or beaded finishes.

Abrasives are extremely commonplace and are used very extensively in a wide variety of industrial, domestic, and technological applications. This gives rise to a large variation in the physical and chemical composition of abrasives as well as the shape of the abrasive. Common uses for abrasives include grinding , polishing , buffing , honing , cutting , drilling , sharpening and sanding . (For simplicity, "mineral" in this article will be used loosely to refer to both minerals and mineral-like substances whether man-made or not.)

Mechanics of abrasion - Abrasives generally rely upon a difference in hardness between the abrasive and the material being worked upon, the abrasive being the harder of the two substances. Typically, materials used as abrasives are either hard minerals or are synthetic stones, some of which may be chemically and physically identical to naturally occurring minerals but which cannot be called minerals as they did not arise naturally. Diamond , a common abrasive, for instance occurs both naturally and is industrially produced, as is corundum which occurs naturally but which is nowadays more commonly manufactured from bauxite . [1] These minerals are either crushed or are already of a sufficiently small size (anywhere from macroscopic grains as large as about 2 mm to microscopic grains about 0.001 mm in diameter) to permit their use as an abrasive. These grains, commonly called grit , have rough edges, often terminating in points which will decrease the surface area in contact and increase the localized contact pressure . The abrasive and the material to be worked are brought into contact while in relative motion to each other. Force applied through the grains causes fragments of the worked material to break away while simultaneously smoothing the abrasive grain and/or causing the grain to work loose from the rest of the abrasive. http://en.wikipedia.org/wiki/Abrasive

Benjamin Chew Tilghman (1821-1903) – was a US Soldier and inventor. He is best known as the inventor of the process of sandblasting. http://en.wikipedia.org/wiki/Benjamin_Chew_Tilghman

Cathodic Protection (CP) – is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. It is a method used to protect metal structures from corrosion. Cathodic protraction systems are most commonly used to protect steel, water/fuel pipelines and storage tanks; steel pier piles, ships, offshore oil platforms and onshore oil well casings. Cathodic protection is an effective method of preventing stress corrosion cracking. http://en.wikipedia.org/wiki/Cathodic_protection

Coating - is a covering that is applied to an object to protect it or change its appearance. They may be applied as liquids , gases or solids. http://en.wikipedia.org/wiki/Coating

Industrial Coatings – is a paint or coatings defined by its protective, rather than its aesthetic properties, although it can provide both. The most common use of industrial coatings is for corrosion control of steel or concrete. Other functions include intumescent coatings for fire resistance. The most common polymers used in industrial coatings are polyurethane an epoxy. http://en.wikipedia.org/wiki/Industrial_coating

Intumescent - is a substance which swells as a result of heat exposure, thus increasing in volume , and decreasing in density . Intumescents are typically used in passive fire protection and require bounding installations in order to comply with the law . http://en.wikipedia.org/wiki/Intumescent

NACE International - is a professional organization for the corrosion control industry established in 1943. As of 2006 , there are approximately 16,003 NACE members world wide. The main areas of activities are cathodic protection , coatings for industry and material selection for specific chemical resistance.

NACE was formerly known as the National Association of Corrosion Engineers.

NACE publishes the journals, Materials Performance (MP) and Corrosion. NACE also publishes recommended standard practice and testing articles for use by industry and other Corrosion societies . Standing committees periodically review and update the standards as required. An annual conference is held in the United States for the entire organization and several regional meeting and conferences around the world. http://www.nace.org/nace

Paint - is a liquid , liquifiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. Paint is used to protect, decorate (such as adding color ), or add functionality to an object or surface by covering it with a pigmented coating. An example of protection is to retard corrosion of metal . An example of decoration is to add festive trim to a room interior. An example of added functionality is to modify light reflection or heat radiation of a surface.

Paint can be applied to almost any kind of object. It is used, among many other uses, in the production of art , in industrial coating , as a driving aid ( road surface marking ), or as a barrier to prevent corrosion or water damage. Paint is a semifinished product , as the final product is the painted article itself. http://en.wikipedia.org/wiki/Paint

Sand - is a granular material made up of fine mineral particles. It is a naturally occurring, finely divided rock . http://en.wikipedia.org/wiki/Sand

Sandblasting or bead blasting – is a generic term for the process of smoothing, shaping and cleaning a hard surface by forcing solid particles across that surface at high speeds; the effect is similar to that of using sandpaper, but provides a more even finish with no problems at corner or crannies. An artificial sandblasting process was patented by Benjamin Chew Tilghman on October 18 th, 1870. Historically, the material used for artificial sandblasting was sand that had been sieved to a uniform size. The silica dust produced in the sandblasting process caused silicosis after sustained inhalation of dust. Sandblasting may now only be performed in a controlled environment using ventilation, protective clothing and breathing an air supply.

Other materials for sandblasting have been developed to be used instead of sand; for example, steel grit, steel shots, copper slag, glass beads (bead blasting), metal pellets, dry ice , garnet, powdered abrasives of various grades, powdered slag, and even ground coconut shells or corncobs have been used for specific applications and produce distinct surface finishes. http://en.wikipedia.org/wiki/Sandblasting

Shot Peening - is a process used to produce a compressive residual stress layer and modify mechanical properties of metals. It entails impacting a surface with shot (round metallic, glass or ceramic particles) with force sufficient to create plastic deformation . http://en.wikipedia.org/wiki/Shot_peening

Surface Finishing - is used to describe a number of industrial processes that can be applied to improve the surface of a manufactured item. The major reason to apply these processes is to improve appearance, improve adhesion or ink wettability, corrosion protection, wear resistance and friction control also are areas where performance can be enhanced by these treatments. In limited cases some of these techniques can be used to restore original dimensions to salvage or repair an item. Generally, surface finishing consists of one of the following: Removing material, or reshaping the item, Adding material to the item's sur face, or chemically altering it. http://en.wikipedia.org/wiki/Surface_finishing