What is Abrasive Blasting?
Abrasive blasting is when a high-pressure stream of air or water removes paint, rust, or other debris from a surface.
It can be used on metal and non-metal surfaces and is often used to prepare surfaces for painting or other forms of finishing. This process is also sometimes used to clean graffiti from buildings or other structures.
Abrasive Blasting is easy to perform and efficient if the correct security measures are in place. There are also portable options, or it can utilize multiple machines if blast rooms are used, for example.
However, abrasive blasting also includes risks if not handled properly. Tiny particles can enter an operator’s lungs and cause diseases like silicosis.
Some natural blast media, such as walnut shells or corn cobs, can trigger an allergic response in some people, potentially resulting in anaphylactic shock.
Components of an Abrasive Blast System
The ten components of Abrasive blasting process include:
#1. Abrasive Blast Pot.
This is the main component of a blasting system that controls and holds the grit or sand used when abrasion is required.
It is used in sand and grit blasting processes to facilitate surface preparation for coating and painting purposes. It is also an ideal equipment for the removal of paints and rust from the substrates.
#2. Blasting Helmet.
Blasting helmet provides safety to blast operators from dust, sand, shot and protect breathing during the process of blasting.
The blasting helmet is a very efficient product which comprises of a head suspension system to allow the device to move with the operator’s head, a view window with replacement lens or lens protection and an air-feed hose.
#3. Blasting Coverall.
Blasting coverall protects blasters from the hazards of abrasive blasting materials. Of all the personal protective equipment used in abrasive blasting, blasting coverall is very close to being the most important of all. Blasting coverall keeps the blasters safe, secure and comfortable during any hazardous process.
#4. Blasting Nozzle.
Blasting nozzle is a device that accelerates the air and an abrasive blasting mixture over a materials surface that exhibits pitting and needs repair and subsequent protection from corrosion. The air and abrasive mixture is discharged from the end of the hose through the blasting nozzle.
An air blasting nozzle is made up of materials such as tungsten carbide, aluminium, boron carbide and silicon nitride that can withstand the force and pressure at the outlet tips nozzle while spraying pressurized air and abrasive at high velocity and pressure on an area with defects or corrosion.
#5. Dead-man Control Switch.
Dead-man control switch or handle are for the remote activation and deactivation of a sandblasting machine. These handles are fail-to-safe systems designed to stop blasting if the operator drops or loses control of the handle.
#6. CPF (Air filter unit).
CPF, also known as air filter unit is a device that removes moisture, oil and dirt particles from compressed air before it reaches your respirator. This device provides breathable air in an immediately hazardous and dangerous to life or health atmosphere.
#7. Blasting Hose.
Blasting hose is an integral part of any abrasive blasting system. Blasting hoses is designed for supply of abrasive materials and is used in jet engines and installations blast cleaning surfaces.
#8. Breathing Hose.
Breathing hose also known as air-line is a tube or hose that contains and carries a compressed air supply from the air compressor or air tank to the blaster’s respirator
#9. Dead-man Hose.
Dead-man hose or twin air-line is a tube that carries and contains compressed air supply from the air compressor or air tank to the sand pots dead-man unit and switch.
#10. Blasting Hand gloves.
Due to the hazardous nature of abrasive blasting, blasters put on hand glove to protect them from abrasive materials that may harm or hurt their hands, hence the need to wear hand gloves during abrasive blasting processes.
Abrasive blasting uses all the components to strip imperfections, paint, rust and other contaminants from a surface. It’s an important step in surface coating preparations as it cleans a substrate and create a surface that will hold a protective coating.
Blasting takes the place of more labor intensive cleaning methods like wire brushing or sanding and can speed up the surface preparation process by up to 75%. Abrasive blasting is generally the most suitable and reliable method of obtaining a visually clean surface and a satisfactory surface profile.
Types of Abrasive Blasting
#1. Sand Blasting.
Sand blasting machinery shoots dry silica abrasive particles at the surface of a part at high velocity.
It uses silica or quartz as the abrasive material, which is then propelled onto surfaces at high speed. The sharpness of the abrasive and the consistency in size made it a great abrasive to use in giving uniform finished.
These particles, given their high speed, will remove any contaminants on the surface of the part with ease. Sandblasting is an especially popular option when it comes to removing rust from metal.
The mechanism uses air pressure to fire these dry abrasive particles.
The abrasive sand material along with the air is generally ejected out of a hand-held nozzle. Because sandblasting is executed in a more open-space format, there are environmental regulations that determine where it can be carried out.
The silica used is hazardous to health and can lead to Silicosis. As a result, this method is no longer preferred when it comes to abrasive blasting as the abrasive can be inhaled or leak into the environment.
Best used for: Diverse surfaces that require versatility.
#2. Wet Blasting.
Wet blasting was designed to solve the big problem with air blasting, which is controlling the amount of airborne dust that results from doing air blasting.
This tool injects water into the nozzle near the exit of the abrasive that’s propelled by high air pressure. In some varieties, water is even mixed with the abrasive in advance and ejected through the nozzle.
In either case, a mixture of air, water, and abrasive particles leave the nozzle and hit the surface at high pressure to help clean it. The by-product of this cleaning exercise needs to be contained and properly disposed of, according to environmental regulations.
Best used for: Surfaces with blasting by products that need to be limited, such as airborne dust.
#3. Vacuum Blasting.
Vacuum blasting is also known as dustless blasting. This involves a blasting machine that comes equipped with a vacuum suction that removes any propelled abrasives and surface contaminants. In turn, these materials are immediately sucked back into the control unit.
The benefit of vacuum blasting is its more effective in the recycling of spent abrasives that can prove to be cost-efficient. In addition to this, any debris from the cleaning is also minimized.
However, the recycling function does make the vacuum blasting method slower than other methods.
Best used for: Any abrasive blasting that requires minimal debris creepage out into the environment.
#4. Centrifugal Blasting.
Centrifugal blasting is also known as wheel blasting. This is when a motor-operated blade wheel hurls the abrasives at incredibly high speeds towards the surface that needs cleaning.
The biggest benefit to this method is that it doesn’t use compressed air pressure making it much more. It’s also known to be a more effective cleaner and produces cleaner and more uniform surfaces.
Issues with centrifugal blasting are that it is a larger machine and is much less portable. It also can’t be operated on uneven services. Abrasives used in centrifugal blasting can also be recycled and debris is collected by a collector unit. Both making it an appealing choice.
Best used for: Any long-term abrasive blasting operations that need efficiency and high throughput.
#5. Soda blasting.
Soda blasting is a newer form of blasting that uses sodium bicarbonate as the abrasive which is blasted onto the surface using air pressure.
The use of sodium bicarbonate has been shown to be very effective at removing certain contaminants from the surface of materials. The abrasive shatters on impact with the surface and exerts a force that clears up contaminants on the surface. It’s a gentler form of abrasive blasting and requires much less pressure exertion. This makes them suitable for softer surfaces such as chrome, plastic, or glass.
A drawback however to soda blasting is the abrasive cannot be recycled.
Best used for: Cleaning softer surfaces that may be damaged by tougher abrasives.
#6. Steel Grit blasting.
Steel Grit blasting uses spherical steels as abrasives. This method is commonly used when attempting to clean metal surfaces. It’s very effective in removing paint or rust on other steel surfaces. The use of steel grit also has added advantages such as providing smoother surface finish and helping in peening which strengthens the metal.
Other materials can also be used instead of steel in this procedure such as Aluminum, Silicon Carbide, and walnut shells. It all depends on what surface material is being cleaned.
Best used for: Any surface that requires a smooth finish and fast cutting removal.
#7. Bristle blasting.
Bristle blasting is the only blasting that doesn’t involve an abrasive being projected onto a surface in order to clean it. In this method, steel wire bristles are directly rotated against the surface of the material to remove contaminants.
This leaves the surface smooth and uniform. It’s a popular method when it comes to cleaning metal surfaces with lots of corrosion.
Best used for: Uniform finish and greater precision due to the direct application of bristles.
#8. Dry-ice blasting.
Dry-ice blasting is a newer and innovative form of abrasive blasting.
It uses high-pressure air pressure along with carbon dioxide pellets that are projected at the surface to clean it. It’s a unique form of abrasive blasting as the carbon dioxide is non-toxic and doesn’t react with the contaminant on the part surface – making it ideal for substances such as cleaning food processing equipment.
These carbon dioxide pellets are made by taking liquid carbon dioxide and freezing it at extreme temperatures to form dry ice pellets. These pellets will appear like snow and when they impact the surface at high velocity, the cold temperature of the pellet and speed of impact creates a thermal shock. This shock helps to break any bonds between the surface and the contaminant – helping to dislodge it.
The pellets then vaporize as the outside temperature is far greater.
The benefit of such a method is how fast and clean it is.
There’s no abrasive that needs to be recycled or cleaned up. Carbon dioxide pellets are non-reactive and environmentally friendly. In fact, it doesn’t actually carry out any abrasion. The pellets remove contaminants without exerting any actual damage to the surface it’s cleaning. This makes it perfect for cleaning sensitive electrical components as well.
Best used for: Any surface that’s delicate and cannot be contaminated with the abrasive.
#9. Pencil blasting.
Pencil blasting, sometimes referred to as micro-blasting is when high-pressure air and fine powder are mixed together before being ejected out as an abrasive.
This abrasive exits through a small nozzle and creates a fine stream that’s highly precise and can be used to clean specific areas of a surface.
Because of the fine-sized nozzle, pressure can also be adjusted with these machines to do a lot more than surface cleaning. It can be programmed to even cut, drill, or deburr surfaces.
Some are even used against diamonds to alter their surfaces and in applications such as glass etching. The biggest advantage and use for pencil blasting are when precision is needed.
Best used for: Any abrasive blasting that requires extreme precision.
#10. Bead blasting.
Finally, bead blasting is another air pressure powered abrasive blasting method that uses glass beads.
These glass beads are effective at cleaning, deburring and peening metal surface. The glass beads are spherical in shape and when impact the surface create a micro-dimple.
In aggregate, this gives off a much more uniform finish. These glass beads are 100% recyclable making it a cost-effective method.
The use of glass beads also results in a much cleaner and bright finish. The use of glass beads also ensures the abrasive is non-toxic and not harmful to the environment.
If using fine glass beads, it’ll give off a dull or satin finish against metals such as aluminum. Coarser beads, on the other hand, will give a uniform but rough finish.
Best used for: Providing surfaces with a bright smooth finish.
Advantages of Abrasive Blasting
Abrasive blasting offers several advantages across a range of applications and industries.
- Effective Surface Preparation: Abrasive blasting is highly effective in preparing surfaces for coatings, painting, or bonding. It efficiently removes rust, old paint, scale, and contaminants, ensuring a clean and receptive surface for subsequent treatments.
- Versatility: It can be applied to a wide variety of materials, including metals, concrete, glass, wood, and more. This versatility makes abrasive blasting applicable in diverse industries such as automotive, aerospace, construction, and art restoration.
- Precision and Control: Operators have precise control over the blasting process, allowing them to adjust factors like pressure, nozzle type, and abrasive material. This level of control enables targeted treatment, ensuring that only the desired material is removed.
- Improved Adhesion: By creating a clean and roughened surface, abrasive blasting enhances the adhesion of coatings, paints, and adhesives. This leads to longer-lasting finishes and improved performance.
- Conservation and Restoration: In historical preservation and restoration projects, abrasive blasting is invaluable for gently removing layers of dirt, grime, and old coatings from delicate surfaces, revealing their original beauty.
- Efficient Cleaning: It’s an efficient method for cleaning large surfaces or complex structures, such as bridges, tanks, and industrial equipment. Abrasive blasting can reach areas that might be challenging to clean using other methods.
- Cost-Effective: In many cases, abrasive blasting can be more cost-effective than other methods of surface preparation or cleaning, especially when dealing with large or intricate structures.
- Environmental Benefits: Depending on the abrasive material used, abrasive blasting can be environmentally friendly. Some alternatives, like crushed glass or baking soda, are non-toxic and can be recycled.
- Speed and Productivity: It can be a very fast process, allowing for rapid surface preparation and treatment. This is particularly important in industries where efficiency and throughput are critical.
- Customizable Finish: The choice of abrasive material, pressure settings, and blasting technique allows for a wide range of surface finishes, from a smooth, even surface to a textured, roughened one.
Common Safety Hazards
Abrasive blasting may also pose safety hazards if the system is not used properly. For example, dusts created from both the media being blasted and the surface can cause health problems if users are too exposed to inhale the dust particles.
Here are some examples of common safety hazards in abrasive blasting:
- Respiratory Illness: The dust from abrasive blasting can contain harmful materials like silica and lead, leading to serious respiratory conditions. Workers must use suitable respirators during operations.
- Hearing Loss: Abrasive blasting equipment generates noise levels over 90 dBA, which can cause permanent hearing loss without proper ear protection.
- Skin Irritation and Abrasion: High-speed particles can irritate or injure the skin. Protective clothing, including gloves and blast suits, is essential.
- Eye Damage: Microscopic particles can cause severe eye injuries. Safety goggles or blast helmets with visors are necessary to prevent vision loss.
- Air Contaminants: Harmful airborne contaminants may be released during blasting. Monitoring air quality and using ventilation systems are important for minimizing exposure.