Abrasive blasting, more commonly known as sandblasting, is the operation of forcibly propelling a
stream of abrasive material against a surface under high pressure to smooth a rough surface,
roughen a smooth surface, shape a surface or remove surface contaminants. A pressurised fluid,
typically compressed air, or a centrifugal wheel is used to propel the blasting material (often called
the media). The first abrasive blasting process was patented by Benjamin Chew Tilghman on 18
October 1870.[1]
There are several variants of the process, using various media; some are highly abrasive, whereas
others are milder. The most abrasive are shot blasting (with metal shot) and sandblasting
(with sand). Moderately abrasive variants include glass bead blasting (with glass beads) and plastic
media blasting (PMB) with ground-up plastic stock or walnut shells and corncobs. Some of these
substances can cause anaphylactic shock to individuals allergic to the media. [2] A mild version
is sodablasting (with baking soda). In addition, there are alternatives that are barely abrasive or
nonabrasive, such as ice blasting and dry-ice blasting.
Contents
1Types
o 1.1Sandblasting
o 1.2Wet abrasive blasting
o 1.3Bead blasting
o 1.4Wheel blasting
o 1.5Hydro-blasting
o 1.6Micro-abrasive blasting
o 1.7Automated blasting
o 1.8Dry-ice blasting
o 1.9Bristle blasting
o 1.10Vacuum blasting
2Equipment
o 2.1Portable blast equipment
o 2.2Blast cabinet
o 2.3Blast room
3Media
4Safety
o 4.1Worn-look jeans
5Applications
6See also
7References
8Bibliography
Types[edit]
Sandblasting[edit]
Sand blasting is also known as abrasive blasting, which 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 corners or crannies. Sandblasting can occur naturally, usually as a result of particles
blown by wind causing aeolian erosion, or artificially, using compressed air. An artificial sandblasting
process was patented by Benjamin Chew Tilghman on 18 October 1870.
Sandblasting equipment typically consists of a chamber in which sand and air are mixed. The
mixture travels through a hand-held nozzle to direct the particles toward the surface or work piece.
Nozzles come in a variety of shapes, sizes, and materials. Boron carbide is a popular material for
nozzles because it resists abrasive wear well.
Wet abrasive blasting[edit]
One of the original pioneers of the wet abrasive (vapourmatting) process was Norman Ashworth who
found the advantages of using a wet process a strong alternative to dry blasting. The process is
available in all conventional formats including hand cabinets, walk-in booths, automated production
machinery and total loss portable blasting units. Advantages include the ability to use extremely fine
or coarse media with densities ranging from plastic to steel and the ability to use hot water and soap
to allow simultaneous degreasing and blasting. The reduction in dust also makes it safer to use
silicacious materials for blasting, or to remove hazardous material such as asbestos, radioactive or
poisonous products.
Process speeds are generally not as fast as conventional dry abrasive blasting when using the
equivalent size and type of media, in part because the presence of water between the media and the
substrate being processed creates a lubricating cushion that can protect both the surface and the
media, reducing breakdown rates. Reduced impregnation of blasting material into the surface, dust
reduction and the elimination of static cling can result in a very clean surface. However wet blasting
of mild steel will result in immediate or 'flash' corrosion of the blasted steel substrate due to the
presence of water. The lack of surface recontamination also allows the use of single equipment for
multiple blasting operations—e.g., stainless steel and mild steel items can be processed in the same
equipment with the same media without problems.
Bead blasting[edit]
Bead blasting paint from a concrete curb. Mixing particles with water substantially reduces dust.
Bead blasting is the process of removing surface deposits by applying fine glass beads at a high
pressure without damaging the surface. It is used to clean calcium deposits from pool tiles or any
other surfaces, remove embedded fungus, and brighten grout color. It is also used in auto body work
to remove paint. In removing paint for auto body work, bead blasting is preferred over sand blasting,
as sand blasting tends to create a greater surface profile than bead blasting. Bead blasting is often
used in creating a uniform surface finish on machined parts. [3] It is additionally used in cleaning
mineral specimens, most of which have a Mohs hardness of 7 or less and would thus be damaged
by sand.
Wheel blasting[edit]
In wheel blasting, a spinning wheel propels the abrasive against an object. It is typically categorized
as an airless blasting operation because there is no propellant (gas or liquid) used. A wheel machine
is a high-power, high-efficiency blasting operation with recyclable abrasive (typically steel or
stainless steel shot, cut wire, grit, or similarly sized pellets). Specialized wheel blast machines propel
plastic abrasive in a cryogenic chamber, and is usually used for deflashing plastic
and rubber components. The size of the wheel blast machine, and the number and power of the
wheels vary considerably depending on the parts to be blasted as well as on the expected result and
efficiency. The first blast wheel was patented by Wheelabrator in 1932. [4]
Hydro-blasting[edit]
Hydro blasting is not a form of abrasive blasting as no abrasive media is used. Hydro-blasting,
commonly known as water blasting, is commonly used because it usually requires only one operator.
In hydro-blasting, a highly pressured stream of water 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 the operator is generally able to send the stream of water into places that are
difficult to reach using other methods. Another benefit of hydro-blasting is the ability to recapture and
reuse the water, reducing waste and mitigating environmental impact.
Micro-abrasive blasting[edit]
Main article: Abrasive jet machining
Micro-abrasive blasting is dry abrasive blasting process that uses small nozzles (typically 0.25 mm
to 1.5 mm diameter) to deliver a fine stream of abrasive accurately to a small part or a small area on
a larger part. Generally the area to be blasted is from about 1 mm2 to only a few cm2 at most. Also
known as pencil blasting, the fine jet of abrasive is accurate enough to write directly on glass and
delicate enough to cut a pattern in an eggshell.[5] The abrasive media particle sizes range from 10
micrometres up to about 150 micrometres. Higher pressures are often required.
The most common micro-abrasive blasting systems are commercial bench-mounted units consisting
of a power supply and mixer, exhaust hood, nozzle, and gas supply. The nozzle can be hand-held or
fixture mounted for automatic operation. Either the nozzle or part can be moved in automatic
operation.
Automated blasting[edit]
Automated blasting is simply the automation of the abrasive blasting process. Automated blasting is
frequently just a step in a larger automated procedure, usually involving other surface treatments
such as preparation and coating applications. Care is often needed to isolate the blasting chamber
from mechanical components that may be subject to dust fouling.
Dry-ice blasting[edit]
Main article: Dry-ice blasting
In this type of blasting, air and dry ice are used. Surface contaminants are dislodged by the force of
frozen carbon dioxide particles hitting at high velocity, and by slight shrinkage due to freezing which
disrupts adhesion bonds. The dry ice sublimates, leaving no residue to clean up other than the
removed material. Dry ice is a relatively soft material, so is less destructive to the underlying material
than sandblasting.
Bristle blasting[edit]
Main article: Bristle blasting
Bristle blasting, unlike other blasting methods, does not require a separate blast medium. The
surface is treated by a brush-like rotary tool made of dynamically tuned high-carbon steel wire
bristles. Repeated contact with the sharp, rotating bristle tips results in localized impact, rebound,
and crater formation, which simultaneously cleans and coarsens the surface.
Vacuum blasting[edit]
Main article: Vacuum blasting
Vacuum blasting is a method that generates very little dust and spill, as the blast tool does dry
abrasive blasting and collects used blast media and loosened particles from the surface to be
treated, simultaneously. Blast media consumption is relatively low with this method, as the used
blast media is automatically separated from dust and loosened particles, and reused several times.
