Abrasive blasting , more commonly known as sandblasting , is a forced operation of pushing the flow of abrasive material to the surface under high pressure to smooth the rough surface, hardening the surface smooth, surface shapes or removing contaminants surface. Pressurized liquid, usually compressed air, or centrifugal wheel is used to induce explosives (often called media ). The first abrasive blasting process was patented by Benjamin Chew Tilghman on 18 October 1870.
There are several process variants, using various media; some very abrasive, while others are lighter. The most abrasive is shot blasting (with metal shot) and sandblasting (with sand). Sufficient abrasive variants include glass beads (with glass beads) and media blasting with ground-to-surface plastic stock or walnut and corncobs. Some of these substances can cause anaphylactic shock for operators and passers-by. The lightest version is sodablasting (with baking soda). In addition, there are almost non-abrasive or non-abrasive alternatives, such as ice blasting and dry ice blasting.
Video Abrasive blasting
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Sandblatsing
Sandblasting or bead blasting is a generic term for the process of smoothing, shaping and cleaning hard surfaces by forcing solid particles on the surface at high speeds; the effect is similar to the use of sandpaper, but gives more evenly results without problems in the nook or cranny. Sandblasting can occur naturally, usually as a result of wind-blown particles that cause aerolian erosion, or artificially, using compressed air. The artificial sandblasting process was patented by Benjamin Chew Tilghman on 18 October 1870.
The sandblasting equipment usually consists of a room where sand and air are mixed. The mixture moves through a handheld nozzle to direct the particles to the surface or workpiece. Nozzles come in different shapes, sizes, and materials. Boron carbide is a popular material for nozzles because it is well abrasive.
Wet abrasive blast
One of the original pioneers of the wet abrasive (vapourmatting) process was Norman Ashworth who found the advantage of using the wet process as a powerful alternative to blasting with silica sand - which is banned in many countries. Open blasting with other abrasive media that does not produce harmful dust is generally accepted as an industry standard.
Common features include: the ability to use very fine or coarse media with densities ranging from plastic to steel, the ability to use hot water and soap to allow degreasing and simultaneous blasting, removal of dust - a very silky material can be used without worry, or waste can be disposed of without harm - for example, the removal of asbestos, radioactivity, or other toxic products from components and structures leading to effective decontamination.
This process is available in all conventional formats including cabinets, walk-in booths, automatic production machines, and portable blasting units of total loss.
Process speed is generally not as fast as conventional abrasive dry blasting when using equivalent media sizes and types. But the presence of water between the medium and the substrate being processed creates a lubricant pad that can protect both the media and the surface from excess damage. It has the dual advantage of lowering the level of damage to the media and preventing the impregnation of foreign materials to the surface. Therefore, the surface after wet blasting is very clean, no secondary contamination is embedded from the media or from the previous blasting process, and no static dust attaches to the accursed surface. Subsequent coating or bonding operations are not affected by the use of wet blasting or dry blasting as the level of cleanliness achieved is identical. However, mild wet steel blasting will result in immediate corrosion or 'flash' of the crushed steel substrate due to the presence of water. The lack of surface recontamination also allows the use of single equipment for some blasting operations - for example, stainless steel and carbon steel (light) can be processed in the same equipment with the same media without any problems.
Blasting bead
Blasting bead is the process of removing surface precipitation by applying fine glass beads with high pressure without damaging the surface. It is used to clean the calcium deposits from swimming pool tiles or other surfaces, remove the embedded mushrooms, and brighten the grout color. It is also used in automated body work to remove paint. In removing paint for automatic body work, blasting beads is preferred over sand blasting, since sand blasting tends to create a larger surface profile than blasting beads. In creating a uniform surface finish on the engine parts. It is also used in cleaning mineral specimens, most of which have Mohs 7 or less hardness and thus will be damaged by sand.
Blasting wheel
On the blasting wheel, the spinning wheel pushes the abrasive against an object. This is usually categorized as a non-air blasting operation because no propellant (gas or liquid) is used. Wheel engines are high-power, high-efficiency recycling operations with recyclable abrasives (usually stainless steel or stainless steel, cut wire, sand, or pellets of the same size). Special wheel blast machines push plastic abrasives in cryogenic chambers, and are usually used to deflect plastic and rubber components. The size of the engine wheel explosion, and the number and strength of the wheels vary depending on the part to be detonated as well as on the expected results and efficiency. The first blast wheel was patented by Wheelabrator in 1932.
Hydro Coating
Hydro explosion is not a form of abrasive blasting because no abrasive media is used. Hydro explosion, commonly known as water blasting, is usually used because it usually requires only one operator. In hydro-blasting, high-pressure water flow is used to remove old paint, chemicals, or buildup without damaging the original surface. This method is ideal for cleaning internal and external surfaces because operators are generally able to send water flow to places that are difficult to reach using other methods. Another benefit of hydro-blasting is the ability to reclaim and reuse water, reduce waste and reduce environmental impact.
Micro-Abrasion Blast
Micro-abrasive blasting is a dry abrasive blasting process that uses small nozzles (typically 0.25 mm to 1.5 mm in diameter) to produce accurate good abrasion flows to small or small areas of larger sections. Generally the area to be detonated is from about 1 mm 2 to just a few cm 2 at most. Also known as pencil blasting, the smooth abrasive jets are accurate enough to write directly on the glass and are smooth enough to cut patterns in egg shells. The size of abrasive media particles ranges from 10 micrometers to about 150 micrometers. Higher pressures are often required.
The most common micro-abrasive blasting system is a commercial-installed unit consisting of a power supply and mixer, hood, nozzle, and gas supply. Hand-held nozzles or fixtures fitted for automatic operation. Either the nozzle or part can be moved in automatic operation.
Auto blast
Automatic blasting is just the automation of the abrasive blasting process. Automatic blasting is often just a step in a larger automated procedure, usually involving other surface treatments such as preparation and coating applications. Treatment is often necessary to isolate the blasting chamber from mechanical components that may be exposed to dirty dust.
Dry ice blasting
In this type of blasting, air and dry ice are used. The surface contaminants are released by the force of high-speed freezing carbon dioxide particles, and a slight shrinkage due to freezing that interferes with adhesion bonds. Dry ice smoothing, leaving no residue to clean apart from the discarded material. Dry ice is a relatively soft material, thus less damaging the underlying material than sandblasting.
Blasting feather
Blasting feathers, unlike other blasting methods, do not require a separate explosion medium. Its surface is maintained by a rotary tool such as a brush made of dynamically adjusted high carbon steel wire. Repetitive contact with sharp and rotating pointed edges produces localized, rebound, and crater-shaped effects, simultaneously cleansing and wetting the surface.
Blasting vacuum
Vacuum blasting is a method that produces very little dust and spills, because the blast tool performs a dry abrasive blasting and collects the explosive media used and looses particles from the surface to be treated, simultaneously. The consumption of blast media is relatively low with this method, since the explosion media used is automatically separated from dust and loose particles, and reused several times.
Maps Abrasive blasting
Tools
Portable explosive equipment
Dry cellular abrasive blast systems are usually supported by diesel air compressors. Air compressors provide large volumes of high pressure air to one or several "explosive pots". The explosive pot is a pressurized container, such as a tank, filled with abrasive material, used to allow an adjustable amount of sand blasting into the main blasting line. The number of explosion pots is determined by the volume of air that the compressor can provide. Complete blast systems are often found mounted on semi-tractor trailers, offering high mobility and easy transportation from site to site. The other is the type that is fed hopper so that it is lighter and more mobile.
In wet blasting, the abrasive is inserted into a pressurized water stream or other liquid, creating a slurry. Wet blasting is often used in applications where the minimum dust generation is desired. Portable applications may or may not recycle abrasives.
Blast Cabinet
The blast cabinet is essentially a closed-loop system that allows the operator to blow parts and recycle abrasives. It usually consists of four components; containment (cabinet), abrasive blasting system, abrasive recycling system and dust collection. The operator blows up parts of the exterior of the cabinet by placing his arm in a glove attached to the hole of the holster on the cabinet, viewing the passage through the view window, turning on and off the explosion using the foot pedal or pedal. Automatic explosive cabinets are also used to process a large number of the same components and can combine multiple blast nozzles and partial transport systems.
There are three systems that are usually used in blast cabinets. Two, siphon and pressure, dry and one wet:
- Siphon spray system (suction blast system) uses compressed air to create a vacuum in the room (known as an explosive gun). Negative pressure pulls the abrasive into an explosive gun where compressed air directs the abrasive through the blast nozzle. The abrasive blend runs through the nozzle that directs the particles to the surface or workpiece.
Nozzles come in different shapes, sizes, and materials. Tungsten carbide is the most commonly used liner material for abrasive minerals. Silicon carbide and boron carbide nozzles are more wear resistant and are often used with harder abrasives such as aluminum oxide. Cheap abrasive blasting systems and smaller cabinets use ceramic nozzles.
- In the blast pressure system, the abrasive is stored in a pressure vessel then sealed. Vessels are pressurized at the same pressure as an explosion hose attached to the bottom of the pressure vessel. The abrasive is measured into the blast hose and delivered by compressed gas through the blast nozzle.
- The wet buoy cabinet uses a system that injects abrasive/liquid slurry into a compressed gas stream. Wet blasting is usually used when the heat generated by friction in dry blasting will damage the part.
Blast Space
The explosive chamber is a much larger version of the explosive cabinet. The blast operator works indoors to harden, refine, or clean the surface of an item depending on the needs of the finished product. The explosion chamber and blast facilities come in a variety of sizes, some of which are large enough to accommodate very large or uniquely shaped objects such as rail cars, commercial and military vehicles, construction equipment, and airplanes.
Each application may require the use of many different tools, however, there are some key components that can be found in a typical blast chamber:
- The confinement or containment system, usually the room itself, is designed to remain sealed to prevent blasting media from escaping
- Blasting system; blasting wheels and air blasting systems commonly used
- Pan explosion - pressurized container filled with abrasive blasting media
- A dust collection system that filters air in the room and prevents particles from escaping
- Material recycling system or media reclamation to collect abrasive blasting media so that it can be reused; this may be a mechanical or automatic pneumatic system mounted on the floor of the blast chamber, or the explosive medium may be collected manually by sweeping or shoveling the material back into the blast pot
Additional equipment can be added for comfort and increased usability, such as overhead cranes for maneuvering of workpieces, wall-mounted units with multiple axes that allow operators to reach all sides of the workpiece, and soundproofing materials used to reduce noise levels.
Media
In the early 1900s, it was assumed that sharp grains gave the best performance, but this later proved to be untrue.
Minerals: Silica sand can be used as a type of abrasive mineral. It tends to break quickly, creating large amounts of dust, exposing operators to the development of silicosis potential, debilitating lung disease. To overcome this danger, silica sand for blasting is often coated with resin to control dust. Using silica as abrasive material is not allowed in Germany, England, Sweden, or Belgium for this reason. Silica is a common abrasive material in non-forbidden countries.
Another common mineralic mineral is garnet. Garnet is more expensive than silica sand, but if used correctly, it will offer equivalent production levels while producing less dust and no safety hazards from dusting. Magnesium sulfate, or kieserit, is often used as an alternative to baking soda.
Agriculture: Usually, crushed peanut shells or fruit seeds. This soft abrasive is used to avoid damage to the underlying material such as cleaning bricks or stones, removing graffiti, or removing coatings from printed circuit boards.
Synthetic: This category includes corn starch, wheat starch, sodium bicarbonate, and dry ice. This "soft" abrasive is also used to avoid damaging the underlying materials such as when cleaning bricks or stones, removing graffiti, or removal of coatings from printed circuit boards being repaired. Sodablasting uses very delicate baking soda (sodium bicarbonate), micro fragmentation of collisions that explode away from the surface material without damaging the substrate.
Additional synthetic abrasives include process by-products (eg, copper slag, nickel slag, and coal slag), engineered abrasives (eg, aluminum oxide, silicon carbide or carborundum, glass beads, ceramic/sand shots), and recycled products (eg, abrasive plastic, sand glass).
Metallic: Steel bullet, iron sand, stainless steel shot, cut wire, copper shot, aluminum shot, zinc shot.
Many of the crude media used in sandblasting often produce the energy released as sparks or light on the impact. The color and size of the spark or light vary significantly, with bright bright orange splashes from steel blasting, to faint blue light (often not visible in the sun or brightly lit workspace) of abrasive garnets.
Security
Cleaning operations using abrasive blasting may present a risk to workers' health and safety, particularly in air blasting or portable spillway applications. There is a large amount of dust created through abrasive blasting of substrate and abrasive. Although much of the abrasives used in the blasting chamber are harmless to themselves, (steel and sand shot, cast iron, aluminum oxide, garnet, abrasive plastic and glass beads), other abrasives (silica sand, copper slag, nickel slag, and staurolites) have varying degrees of danger (usually free silica or heavy metals). However, in all cases its use may pose serious harm to the operator, such as burns due to projection (with skin lesions or eyes), falling due to walking in rounds of spacecraft, exposure to harmful dust, heat exhaustion, explosive atmosphere creation, and exposure excessive noise. Blasting rooms and portable blaster equipment have been adapted to this danger. Lead-based paint blasting can fill the air with lead particles that can be harmful to the nervous system.
In the US Occupational Safety and Health Administration (OSHA) mandated engineered solutions for potential hazards, silica sand is still permitted although the most commonly used explosive helmets are not effective enough to protect blasting operators if dust levels exceed the allowable limits.. Adequate respiratory protection rates for blasting operations in the United States are approved by the National Institute for Occupational Health and Safety (NIOSH).
Typical security equipment for operators including:
- Cover or helmet with positive pressure - The hood or helmet includes a head suspension system to allow mobile devices with operator heads, display windows with replaceable lenses or lens protection and air feeder hoses./li>
- Air Supply Class-D (or separate airless oil pump) - Air feed hose usually attaches to a D-grade pressure air supply. Air Grade-D is mandated by OSHA to protect workers from harmful gases. These include pressure regulators, air filtration and carbon monoxide monitor/alarms. An alternative method is an independent non-lubricated air pump to feed pressurized air to the hood/helmet. Airless pumps do not require air filters or carbon monoxide monitors/alarms, because pressurized air comes from sources that can not produce carbon monoxide.
- Hearing protective equipment - earplugs or earplugs
- Body protection - Body protection varies depending on the application but usually consists of gloves and a suit or a coat and a leather chap. Professionals will wear cordura/canvas suits (except blasting with steel abrasives, then they will use a leather suit).
In the past, when sandblasting was done as an open job, the worker was exposed to the risk of injury from flying materials and lung damage from inhalation of dust. The silica dust produced in the sandblasting process will cause silicosis after continuous inhalation of the dust. In 1918, the first sandblasting enclosure was built, which protects workers by display screens, revolves around workpieces, and uses fans to pull dust away from workers' faces. Silicosis is still a risk when the operator is not completely isolated from the sandblasting apparatus.
Sandblasting can also pose a secondary risk, such as falling from a scaffold or confinement in a small space. Carbon monoxide poisoning is another potential risk, from the use of small gasoline-powered engines in abrasive blasting.
Some countries and territories now manage sandblasting in such a way that it can only be done in a controlled environment using ventilation, protective clothing and air supply respiration.
Obsolete looking jeans
Many consumers are willing to pay extra for jeans that have the appearance of being used. To give the cloth look sandblasting worn properly used. Sandblasting has the risk of causing silicosis in workers, and in Turkey, more than 5,000 workers in the textile industry suffer from silicosis, and 46 are known to have died because of it. Silicosis proved very common among the former sandblaster denim in Turkey in 2007. A study in 2015 confirmed that silicosis is almost unavoidable among sandblaster marks. The Swedish Fair Trade Center conducted a survey among 17 textile companies that showed very few were aware of the dangers posed by sandblasting jeans manually. Some companies say they will remove this technique from their own production.
In 2013, research suggests that in China some factories produce obsolete looking jeans engaging in various non-compliance with health and safety regulations.
Apps
Letters and carvings in most modern burial monuments and markers are made by abrasive blasting.
Sandblasting can also be used to generate three-dimensional signage. This type of signage is considered a higher end product than a flat mark. These signs often incorporate a gold leaf overlay and sometimes a crushed glass background called smalts. When sandblasting wood signage allows wood grain to be displayed and growth rings to be raised, and is a popular way to give a traditional carved look. Sandblasting can also be done on clear acrylic glass and glass as part of the front or interior design of the store.
Sandblasting can be used to renew buildings or create artwork (ornate or frosted glass). Modern and resistant masks facilitate this process, producing accurate results.
The sandblasting technique is used to clean the hull of the boat, as well as brick, stone, and concrete work. Sandblasting is used for industrial cleaning as well as commercial structures, but is rarely used for nonmetallic workpieces.
See also
- Abrasion (mechanical)
- Rough machining
- High frequency impact care
- Peening Shot
References
Bibliography
- The Manufacturing Process Reference Guide by Robert H. Todd, Dell K. Allen, and Leo Alting - 1st edition.
- Manufacturing and Manufacturing Technician Handbook, Vol 1: Machining, 4th Edition, 1983. Manufacturing Engineers Association
Source of the article : Wikipedia
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