Abrasive blasting vs Sandblasting — What’s the best method?
Businesses that use metal parts and heavy equipment need to keep their surfaces perfectly clean before any use. In the business of finishing, abrasive blasting and sandblasting are the standard ways of cleaning, altering, and finishing metal surfaces.
However, there is a difference between these two methods of surface preparation; they are different and distinct processes that perform best in various circumstances. So, what’s the difference between abrasive blasting and sandblasting?
What is sandblasting?
Various abrasive cleaning procedures have been referred to be sandblasting because sand was used as the only medium for the process. Today, sand is no longer used because it's considered harsher for blasting projects. Sandblasting produces a lot of sand dust, which results in health problems when inhaled.
Consequently, many industries have turned to alternative materials such as copper slag, steel grit, powder abrasives, and walnut shells for blasting. Sandblasting requires extremely careful monitoring for health and safety reasons. That is why it is important that if you ever choose to have abrasive blasting done on-site, that you get people with the right expertise, and experience to get the job done in a safe and professional manner [We discussed this on another blog post on what to look for when hiring an Abrasive blasting & Painting Specialist].
If done correctly, it’s one of the most effective ways of etching and cleaning metal surfaces.
What is abrasive blasting?
Abrasive blasting is a surface treatment process that involves the propelling of abrasive materials at a high velocity onto a surface. This process is used to create decorative patterns, applying coatings, or removing unwanted coatings on the surface. Abrasive blasting is often used to create intricate shapes or edges. In this process, different media are used for blasting. There are various methods of abrasive blasting, depending on the media used.
The Different Types of Abrasive Blasting
Different types of abrasive blasting use different abrasives to finish, clean, roughen, or smoothen a surface. Each modification caters to a specific need when it comes to the preparation of surfaces before use. The best thing about abrasive blasting is that energy is used efficiently, and the abrasives can be recycled for different other applications.
1. Steel grit blasting
The blasting process utilises spherical steel pieces as the medium. It is commonly used for cleaning metal surfaces. It's quite effective in getting rid of rust or paint on steel surfaces. Steel grit blasting also gives the surface a much smoother finish. It assists with peening, which is known to strengthen the metal. In place of steel, you can use walnut shells, silicon carbide, or aluminum.
2. Pencil blasting (also known as Micro-blasting)
In the process, fine powder and high-pressure air are mixed before being propelled as an abrasive. This abrasive is ejected through the nozzle, creating a fine stream that helps to clean specific areas of a surface. Since the nozzle is fine-sized, you can easily adjust machine pressure to do more on the surface. You can program it to deburr, drill, or even cut surfaces. Some are used to alter the surfaces of diamonds and glass etchings. Pencil blasting can be used anywhere precision and fine detail is needed.
3. Bead Blasting
Bead blasting is another abrasive blasting method powered by air pressure. Glass beads are used as abrasives, and the technique is useful for peening, deburring and cleaning metal surfaces. These glass beads have a spherical shape, and their impact on a surface creates a micro-dimple, which helps provide a uniform finish.
The biggest benefit of glass beads are that they’re more cost-effective and eco-friendly because it’s 100 per cent recyclable. This blasting method provides a brighter and cleaner finish. When using fine beads, you can get a satin or dull finish on metals like aluminium. On the other hand, coarser glass beads give you a rough but uniform finish.
4. Dry ice blasting
Dry ice blasting is a newer, innovative type of abrasive blasting that uses high pressure with pellets of carbon dioxide to clean a surface. The abrasives are projected onto the surface to remove contaminants and unwanted coatings. These pellets are non-toxic and won't react with the contaminants on the surface. This makes it suitable for cleaning heavy equipment in food processing plants.
Dry ice pellets are made from liquid carbon dioxide that is put under extreme temperatures to freeze. The pellets are frozen like snow, and when they impact a surface at a high velocity, their speed and cold temperature creates thermal shocks. These shocks help in breaking the bonds between the contaminants and surface, hence dislodging it. Then the pellets vaporise due to the temperatures outside.
This abrasive blasting method is perfect for cleaning sensitive electrical components because the pellets don't exert any damage on the surface.
So which option is best?
At the end of the day, using the alternative abrasive blasting methods are a lot safer for your employees and working environment. Although it’s the most effective method, sandblasting can be messy and dangerous if not done by a professional. That’s why it’s best to use alternative methods because they are clean and don't produce any dust, unlike sandblasting. These processes are environmentally friendly and are very useful in surface preparation.
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