Sandblasting is a type of abrasive blasting process that prepares surfaces using a propellant stream containing an abrasive material that may be dispersed in a number of different ways. Sandblasting media can be sand, but other options exist as well, such as organic materials like fruit kernel shells or crushed nuts or steel shot. The stream in which they are delivered is usually air or water, or occasionally, centrifugal force. Whatever it is and however it is delivered, once sandblasting media makes contact with a surface, it cleans, strips or roughens it preparation for further treatment or finishing.
Quick links to Sandblasting Machinery Information
Design of Sandblasting Machinery
Because there are so many different equipment configurations available to manufacturers, sandblasting machinery can actually be divided into several categories based on their complexity, their physical size and their ideal applications; examples include blast rooms, blast cabinets and portable systems. Of the three, designed to prepare one very large or several average-sized parts at once, blast rooms are the largest example of sandblasting machinery. They usually consist of a sealed room inside which a trained worker wearing protective gear operates the whole system. They contain a dust extraction and ventilation system, or dust collector, a containment structure, or cabinet, and, of course, an abrasive blasting system. In addition, they are often equipped with a recycling system to reclaim and reuse leftover media. Recycling systems range from manual shoveling and sweeping to full reclaim floors. Next, blast cabinets are like blast rooms, but smaller. This type of self-contained sandblasting machinery consists of a cabinet, or containment, an abrasive blasting system, an abrasive recycling system and a dust collector. Their operators control them by reaching inside gloves attached to glove holes in the machine and manipulating pieces inside, as well as by observing through a viewing window and turning the blast on and off with a foot pedal or a treadle. Finally, portable sandblasting equipment is the smallest sandblasting machinery of all. They are often moved from one location to another by hand or on semi-tractor trailers. If they send out dry blasts, they are most likely powered by a diesel compressor. If they blast wet media, they direct it through a nozzle that is attached to a pressurized blast hose that is attached to a sealed pressure vessel. Before blasting, this media is converted into a slurry by being mixed with pressurized water or another liquid.
Abrasive Materials for Sandblasting
Abrasive materials used in sandblasting range from mineral types, to natural types, to metallic types to synthetic types.
- Mineral Abrasives
- Some common mineral abrasives include silica sand, garnet and kieserite, or magnesium sulfate. While silica sand is a popular option in many countries, it is banned in Belgium, Sweden, Germany and the United Kingdom. The reason for this is that, for one, it creates a large amount of dust that exposes those around it to the possible development of a lung disease called silicosis. In addition, to control the spread of dust, silica is often coated with resins that are not healthy either. The mineral garnet is an alternative to silica that does not pose any health risks and can facilitate blasting at the same rate. However, it is initially more expensive. Next, kieserite is a magnesium sulfate mineral, most well-known for its part in the production of Epsom salt, that works well as an alternative to baking soda media.
- Agricultural Abrasives
- Natural, or agricultural, abrasives include things like crushed walnut shells and fruit kernels. Their relative softness makes them a safer choice for products at risk for damage during cleaning, such as brick, stone or printed circuit boards.
- Metallic Media
- Among the most widely used abrasives are metallic media. This group includes zinc shot, aluminum shot, copper shot, steel shot, stainless steel shot, cut wire and steel grit, among others.
- Synthetic Abrasives
- Synthetic abrasives can be grouped into groups of soft and coarse materials. Softer synthetic abrasives include materials like wheat starch, corn starch, dry ice and sodium bicarbonate, more commonly known as baking soda. Examples of coarser synthetic abrasives include: process byproducts like coal slag, nickel slag and copper slag, recycled products like glass grit and plastic abrasive, as well as engineered abrasives like silicon carbide, aluminum oxide, glass beads, ceramic shot, ceramic grit and carborundum.
- Soft Abrasives
- Soft abrasives, like organic abrasives, are useful for the gentle cleaning of brick and stone, the careful removal of coatings from printed circuit boards and the removal of graffiti. Soda blasting in particular uses baking soda in its endeavors.
Sandblasting Machinery Safety
When working with sandblasting machinery, workers must take care to wear and use the proper safety equipment. This includes: a grade-D air supply or a self-contained oilless air pump, ear plugs or ear muffs for ear protection, a positive pressure blast hood or helmet and, at the very least, gloves and overalls (though a cordura/canvas blast suit is preferable). When approached with the right precautions and operated with due diligence, sandblasting machinery is an excellent and essential investment.