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Why is choosing the right abrasive media for the job so important?crush
If you use a mismatched abrasive for a blasting job, you may end up having to redo the job, because the anchor pattern is incorrect, or cause unwanted damage to the blasted surface.
There are several types of abrasive blasting applications: cleaning, finishing, and surface prep for coatings, to name a few. By using the appropriate type of abrasive media, along with the right type of delivery, wet or dry blast, direct pressure or siphon blast, you will set yourself up for a successful, profitable blasting job.
Selecting the right abrasive media for surface prep is vital. This is because different media types have different characteristics, and create different surface profiles.
The anchor pattern that an abrasive creates will determine how effectively a coating bonds to a prepared surface.
What type of anchor pattern you need to create to apply a coating depends on the surface being treated.
Some of the things you should consider when choosing an abrasive are hardness, density, shape of the abrasive, the type of profile the abrasive will leave, friability, how many times you can recycle the abrasive, and overall cost.
One of the things abrasives are measured by is the Mohs Hardness Scale. This hardness scale was created by German mineralogist and geologist Freidrich Mohs.
How the scale works is the lower the number, the softer the mineral. The higher the number, the harder the mineral. Talc is a 1, diamond is a 10. Higher number materials can scratch or etch lower number materials.
Here&#;s the Mohs hardness for several popular abrasives.
AbrasiveMohs HardnessAluminum Oxide9Crushed Glass5 to 6Glass Beads5 to 6Garnet7.5 to 8.5Silicon Carbide9 to 9.5Nickel Slag7Copper Slag7Steel Shot8Steel Grit8Plastic Abrasive3 to 4Staurolite7 to 7.5Sodium Bicarbonate2.5Walnut Shell4 to 5Corn Cob4 to 4.5The softer the abrasive, the finer the finish will be. Harder abrasives are useful for removing certain types of corrosion and rust. Softer abrasives are best for cleaning up grease, grime, and removing light coatings. Softer abrasives are preferred when you do not want to leave an anchor pattern in the substrate.
Also, the more pressure you blast with, the velocity and force the abrasive will be thrown with. You can always adjust the blasting pressure, but you cannot change the characteristics of the abrasive itself. For that reason, it is important to look at the shape, as well as the hardness of an abrasive.
Blasting abrasives each a different density. In simplest terms, the more dense a molecule is, the tighter the atoms are packed together. The denser the substance, the more kinetic energy it can hold.
The denser the particle, the more impact it has over a smaller area, meaning a deeper surface profile. Less dense particles create a less deep profile, since they hit with less force. (Speed + mass = force of impact).
Density is measured in specific gravity, with water being a 1.0 SG. The more dense a substance is, the higher specific gravity it will have.
AbrasiveDensity (Specific Gravity)Walnut Shell1.2 to 1.35Corn Cob1.2 to 1.4Plastic Abrasive1.5Sodium Bicarbonate2.2Glass Beads2.5Crushed Glass2.5Copper Slag2.8 to 3.6Nickel Slag2.8 to 3.8Silicon Carbide3.2 to 3.22Staurolite3.6Garnet3.5 to 4.3Aluminum Oxide3.94 to 3.96Steel Shot4.8 to 7.8Steel Grit4.8 to 7.8There are four basic shapes in abrasives: angular, sub-angular, sub-rounded, and rounded.
Angular abrasives have many facets, and several jagged faces and vertices. Examples of angular abrasives are crushed glass and certain types of slag. Angular abrasives are good for stripping corrosion and rust.
Sub-angular abrasives have some jagged edges, but less than angular types. Some abrasives that fall in this category include garnet and plastic urea.
Sub-rounded abrasives are not quite smooth, and the jagged edges are almost gone. This type of abrasive include staurolite and walnut shells.
Rounded abrasives are smooth, or may even be spherical. Glass beads or steel shot would be examples of rounded abrasives. Usually, rounded abrasives are used for removing mill scale (from hot rolled steel) or thin factory coatings.
As the blast media hits the surface, it creates substrate profiles in the shape of the abrasive.
Rounded abrasives create a dimpled profile, like the surface of a golf ball. This is also known as peening.
Angular and sub-angular abrasives create deeper, more pronounced anchor patterns. When the blasted abrasive hits the surface, two things happen: an indentation is made in the surface, and part of the surface is pushed up around the indentation. For every action, there is an opposite and equal reaction.
The indentations in the surface are known as valleys; the part of the surface pushed upwards are known as peaks. The distance between the top of the peak and bottom of the valley is known as a depth profile.
Each coating has a specific depth profile that must be achieved for optimal bonding. This is the surface roughness, or anchor pattern that best allows the coating to set. Ideally, the coating will cover the peaks and fill the valleys.
If the peaks are too high, they may push up through the coating, and rust will prematurely form. If the depth profile is not deep enough the coating may not adhere correctly, and prematurely erode. Ideally, your applied coating will cover the peaks and fill the valleys.
The size of the abrasive, as well the shape, has an effect on the resulting anchor profile.
Generally speaking, it is best to use the finest abrasive available that will create the necessary surface profile.
Abrasives are usually measured in grit size, microns, or mesh size.
The company is the world’s best aluminum oxide grit sizes supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
You can also find a more complete grit size to microns to mesh to inches chart here.
Some blasting abrasives, like aluminum oxide or silicon carbide, cost more up front, but are economical in the long run, because they can be recycled many times.
Other types of abrasive blast media, like crushed glass or metal slag, are primarily used for outdoor blasting, and meant to be used and cleaned up. These are usually cheaper than other blast media, but only good for a few recycles in a blast cabinet or blast room.
Some abrasives are in the mid-range of cost and recycles. Glass beads or plastic urea both fit this description.
Consider what types of abrasive blasting jobs you do most frequently, and what type of media you need to stock to be profitable and efficient.
Abrasive Recycle Rate by Media TypeAbrasive TypeMax Impact Pressure (Siphon)Max Impact Pressure (Direct Pressure)Cold Roll Steel Part HardnessRecycle Uses AverageGlass Beads80 PSI40 PSIB72 to B usesAluminum Oxide90 PSI45 PSIB72 to B usesSilicon Carbide80 PSI40 PSIB72 to B to 100 usesSteel Shot130 PSI100 PSIB72 to B usesPlastic Urea80 PSI40 PSIN/A30 usesWalnut Shells70 PSI35 PSIN/A4 to 5 usesSodium Bicarbonate70 PSI40 PSIN/ASingle UseSlag50 PSI25 PSIN/A2 to 3 usesGarnet60 PSI30 PSIN/A4 to 5 usesThere are many types of abrasives for many different types of blasting applications. This chart compares the most common abrasives for a variety of factors.
AbrasiveMohs HardnessDensityShapeMesh SizesFriabilityRecyclesCostSourceAluminum Oxide93.94 to 3.96Angular / Sub Angular12 to 325Low to Med50$$$MfgCrushed Glass5 to 62.5Angular30 to 325Med1 to 3$MfgGlass Beads5 to 62.5Rounded30 to 325Med30$$$MfgGarnet7.5 to 8.53.5 to 4.3Sub Angular / Sub Round8 to 150Med4 to 5$$$NatSilicon Carbide9 to 9.53.2 to 3.22Angular8 to 325Low70 to 100$$$$MfgNickel Slag72.8 to 3.8Angular12 to 80High2 to 3$B-PCopper Slag72.8 to 3.6Angular12 to 80High2 to 3$B-PSteel Shot84.8 to 7.8Rounded7 to 120High100+$$$MfgSteel Grit84.8 to 7.8Angular / Sub Angular10 to 200High100+$$$MfgPlastic Abrasive3 to 41.5Sub Angular12 to 80Med to High30$$$MfgStaurolite7 to 7.53.6Sub Rounded20 to 120Med2 to 3$$NatSodium Bicarbonate2.52.2Sub Rounded70 to 220Very HighSingle Use$$MfgWalnut Shell4 to 51.2 to 1.35Sub Rounded / Sub Angular6 to 100Med-High4 to 5$$$B-PCorn Cob4 to 4.51.2 to 1.4Sub Angular8 to 40Med-High4 to 5$$B-PIf you have any questions, please contact us, and we&#;ll be happy to help you make the best choice for your needs.
Whether you&#;re searching a sandblasting cabinet for your shop or for your personal garage, there are several things to consider before purchasing this important industrial tool.
Sand blaster cabinets, also known as media blast cabinets or abrasive blasting cabinets, are metal boxes with openings, windows, and attached gloves which allow you to use sand or another abrasive media form, to smooth rough surfaces, remove imperfections in metal, and scrap of old paint or rust.
Yet, while all sandblast cabinets are made for the same general purposes, there are many different specifications.
Types of Sand Blasting Equipment
Sand blasting machines are made in a few different styles: standard, split-level, and portable. While all three styles operate in similar fashion and can use various types of blasting media, there are significant differences to each. Choosing which style will work best for you depends on how often you want to use your sand blaster and for what purposes.
These fixed cabinet blasters have openings in the front and on both sides of the machine. They&#;re great for working on small to medium sized objects.
Split-level blaster cabinets are also fixed and have a hatch top that opens upward on a hinge to create a larger work space. These cabinets are useful when working on larger or heavier objects.
Portable sand blaster cabinets, sometimes called mini sand blasters, are perfect for working with smaller or more delicate objects because they allow your to make more detailed alterations. And, of course, benchtop sandblast cabinets are completely movable, making jobs outside of your workshop or garage possible. They offer remote control operation and are usually more inexpensive than other types of sandblaster cabinets for sale.
Once you&#;ve chosen the best sandblasting equipment style for your needs, the next decision you should make is whether you want to use a siphon cabinet or a direct pressure cabinet.
The question here is how you want your machine deliver your abrasive media to the blasting nozzle.
Siphon cabinets, also known as suction cabinets, are best for light to occasion use, general cleaning and light production jobs. They use a gun to pull abrasive media into your blasting nozzle where it is then shot from the end of the nozzle. This requires the use of more air pressure than direct pressure cabinets because the delivery is a two-step process.
However, these systems are easier to use and install and are generally less expensive than direct pressure cabinets.
These machines can expel abrasive media at a higher blasting flow rate than siphon blasting cabinets can because, unlike the siphon delivery, this system pushes the abrasive media out directly, making completing your jobs on average much faster. The direct pressure cabinets also allow you to lower and raise the pressure to customize the flow rate for each job you do.
Aside from these choices, there are other considerations too. Media blast cabinet details varies with each model and some have better features than others.
Here are some helpful tips and warnings to guide you through the details and specs of the blasting machines you&#;re considering.
If you&#;re buying a standard cabinet, make sure you know what material the cabinet doors are made of. Avoid cabinet blaster machines with plastic doors, which can warp and bow out easily and could lead to machine malfunction.
Some Sandblast cabinets are sold with their own air compressor unit; however, not all are. If you&#;re thinking about purchasing a sandblast cabinet without an included air compressor, make sure to check the required PSI and CFM for your new sandblast cabinet to check if it with work with your current air compressor.
The metal used for frame and body construction also impacts the quality and durability of your sandblasting cabinet. While machines with lighter steel bodies are cheaper and work fairly well for occasional use, if you&#;re planning on using your blasting cabinet on a regular basis, you will need to invest in a machine with a sturdier construction, such as heavy gauge steel.
Some cabinet blasters come with interior lighting. While this is not always necessary for daily use, if you want extra, focused lighting to help you in your detailed work, a sandblast cabinet with an interior light is ideal.
Another, more humdrum consideration is whether the cabinet you&#;re purchasing is fully constructed or will require assembly. Sand blasting cabinets may require hours of assembly and the assembly could be quite complex, especially if you have no prior knowledge of how these machines are built and work.
So, once you&#;ve decided on the types of sandblasting cabinets and systems and thought about the specific features you want, you can start shopping the sandblasting machines for sale.
Before deciding on which type of sandblasting cabinet to purchase, you should ask yourself these questions to help you narrow your search and ensure you find the sand blasting machine that fits your needs:
· What do I want to use my sandblasting cabinet for?
· How often do I want to use my sandblasting cabinet?
· What is my price range?
· Where am I going to use my sandblasting cabinet?
Knowing the answers to these questions will greatly reduce the time you spend deciding between different sand blasting machines.
In the end, the perfect sandblasting cabinet for you is out there. You just need to think about what features, styles, and specification will work best for what you want to use your sand blast cabinet for!
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