Blasting

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Sandblasting From Wikipedia, the free encyclopedia Man sandblasting a stone wall Device used for adding sand to the compressed air (top of which is a sieve for adding the sand) Diesel powered compressor used as an air supply for sandblasting 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 f
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  Sandblasting From Wikipedia, the free ency Man sandblasting a stone wallDevice used for adding sand tosand)Diesel powered compressor uslopediat   he compressed air (top of which is a sieve fe   d as an air supply for sandblastingor adding the  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 athigh speeds; the effect is similar to that of using sandpaper, but provides a moreeven finish with no problems at corners or crannies. Sandblasting can occurnaturally, usually as a result of the particle blown by the wind causing eolian erosion,or artificially, using compressed air. An artificial sandblasting process was patentedby Benjamin Chew Tilghman on October 18, 1870.Historically, the material used for artificial sandblasting was sand that had beensieved to a uniform size. The silica dust produced in the sandblasting processcaused silicosis after sustained inhalation of dust. Sandblasting may now only beperformed in controlled environment using ventilation, protective clothing andbreathing air supply (as it is shown in the top image).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), metalpellets, dry ice, garnet, powdered abrasives of various grades, powdered slag, andeven ground coconut shells or corncobs, walnut shells, baking soda have been usedfor specific applications and can produce distinct surface finishes. Some commercialgrade blasters are specially designed to handle multiple blast abrasives. Theseblasters are commonly referred as multi-media blasters.Sandblasting can also be used to produce three dimensional signage. This type ofsignage is considered to be a higher end product as compared to the flat signs.These signs often incorporate gold leaf overlay and sometimes crushed glassbackgrounds which is called smalts.Sandblasting can be used to refurbish buildings or create beautiful works of art(carved or frosted glass). Modern masks and resists facilitate this process,producing accurate results.Sandblasting technique is used for cleaning of boat hulls, bricks and concrete work.Sandblasting which is also known as blast cleaning is used for cleaning industrial aswell as commercial structures.  Abrasive Blasting Operations Abrasive Blasting: Abrasive blasting or air blasting is a method of propelling abrasiveusing a compressed gas (typically air) or pressurized liquid (typically water) as thepropellant. There are numerous generic terms for this application usually related tothe abrasive media in use; common terms include sand blasting, shot blasting, gritblasting, bead blasting and blast cleaning.The large variety of applications creates the need for a diversity of equipment:Portable blast equipment (aka blast pot): Dry abrasive blasting applications aretypically powered from a diesel air compressor. Most applications involve apressurized vessel that contains the abrasive and meters it into the compressed airstream. Wet blasting is accomplished by injecting the abrasive into a pressurizedwater stream or creating a slurry of abrasive and water that is pressurized orintroduced into a compressed air stream. Wet blasting is often used in applicationswhere the minimal dust generation is desired. Portable applications may or may notrecycle the abrasive and portable dry blasting generally does not attempt to containor minimize the dust generated from the operation.Blast cabinet: A blast cabinet is essentially a closed loop system that allows theoperator to blast the part and recycle the abrasive. A typical blast cabinet consists offour components; the containment (cabinet), the abrasive blasting system, theabrasive recycling system and the dust collection. The operator blasts the parts fromthe outside of the cabinet by placing his arms in gloves attached to glove holes onthe cabinet, viewing the part through a view window and, typically, turning the blaston and off using a foot pedal or treadle. Automated blast cabinets are also used toprocess large quantities of the same component and may incorporate multiple blastnozzles and a part conveyance system.There are three types of blast systems used in a blast cabinet. Two systems (siphonand pressure) are dry and one is wet:A siphon blast system (aka suction blast system) uses the compressed air to createvacuum in a chamber (known as the blast gun). The negative pressure pullsabrasive into the blast gun where the compressed air directs the abrasive through ablast nozzle.  A pressure blast system incorporates a pressurized vessel. The abrasive is stored inthe pressure vessel then sealed. The vessel is pressurized to the same pressure asthe blast hose attached to the bottom of the pressure vessel. The abrasive ismetered into the blast hose and conveyed by the compressed gas through the blastnozzle.Wet blast cabinets use a slurry system that injects the slurry into a compressed gasstream. Wet blasting is typically used to create a surface profile when the frictionalheat of dry blasting would damage the part.Blast room: This is a larger version of a blast cabinet with the exception that theblast operator works inside the room. A blast room always has three of the fourcomponents of a blast cabinet: the containment, the abrasive blasting system andthe dust collector. Most blast rooms have recycling systems ranging from manualrecycling (sweeping and shoveling the abrasive back into the blast pot) to fullreclaim floors that convey the abrasive pneumatically or mechanically to a devicethat cleans the abrasive prior to recycling. Wheel Blasting : Wheel blasting or shot blasting is typically categorized as an   airless blasting operation because there is not a propellant (gas or liquid) used topropel the abrasive. Rather, a centrifugal wheel is used to propel the abrasiveagainst the substrate. Wheel machines are a high-power, high-efficiency blastingoperation with recyclable abrasive (typically steel or stainless steel shot, cut wire,grit or similar sized pellets). Specialized wheel blast machines propel plasticabrasive in a cryogenic chamber; this type of wheel blasting is usually used fordeflashing plastic and rubber components. The size of the wheel blast machine, andthe number and power of the wheels vary considerably depending on the parts to beblasted as well as on the expected result and efficiency. Hydro-Blasting : Hydro-blasting, commonly known as water blasting, is a common   abrasive blasting operation because it is very effective and, in most cases, will onlyrequire one operator. Hydro-blasting is the process by which a highly pressuredstream of water is used to remove old paint, chemicals, or buildup without damagingthe srcinal surface. This method is ideal for cleaing internal and external surfacesbecause the operator is generally able to send the stream of water in places thatpreviously were deemed unreachable. A major benefit of hydro-blasting is the abilityto recapture and reuse the water, thus eliminating waste and the impact on theenvironment.
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