1. Introduction
Do you have aluminum alloy components that need resurfacing or parts machined on a CNC machining center that need cleaning and deburring? Are you in the business of restoration of surfaces of automobile parts like alloy wheels, engine parts, and similar other components? Then a wet blast cabinet is the perfect surface preparation equipment for you.
If your business deals with stripping old coatings, cleaning, resurfacing, and restoration of surfaces, and a dry-blast cabinet does not give you the finish that you require, then your solution lies in a wet-blast cabinet
Please go through this complete guide to wet blast cabinets to know more about this amazing equipment.
Wet blast cabinet is known by different names viz. vapor blast cabinet, dustless blast cabinet, slurry blast cabinet, and vapor honing cabinet, but they are essentially the same. Dry blast cabinets have been around for centuries, but, wet blast cabinets are relatively new and are defining new standards for surface cleaning and surface preparation.
A general understanding of the mechanics of a wet blast cabinet will help you decide on a suitable size wet blast cabinet for your specific needs.
2. What is wet blasting and how it differs from dry blasting?
Wet blasting is a process of stripping and cleaning surfaces by propelling a mix of water and abrasive media onto the blasting surface. A wet blast cabinet uses the wet blasting process inside a sealed enclosure.
Dry blasting is a process of stripping the surfaces of paint or corrosion by propelling dry media at high pressure onto the blasting surface. A dry blast cabinet uses the dry blasting process in a sealed enclosure.
Let us understand how a wet blast cabinet differs from a dry blast cabinet.
Wet blast cabinet: A wet blast cabinet is a compact enclosure where the components can be cleaned or stripped of paint, rust, oxidation, grease, or other contaminants. The used slurry (mix of water and abrasive media) is collected in the sump and can be filtered and recycled multiple numbers of times. Depending on the abrasive media used, the wet blasting provides the surface an etched anchor profile, a smooth finish, or a polished finish.
The slurry pump pumps the slurry into the blast gun and the compressed air entering from the other port propels the slurry onto the blasting surface. The blasting velocity can be varied. In wet blasting, the water molecules envelop the media particles and act as a dampener resulting in a gentle, yet efficient cleaning and resurfacing of the component.
The major advantage of wet blasting is the smooth, uniform, and feathered finish that the water provides, the cool temperature that protects delicate surfaces, and the cleaning and degreasing through the use of water.
Dry blast cabinet: A dry blast cabinet externally looks similar to a wet blast cabinet and uses compressed air to propel the abrasive media onto the blasting surface inside the compact enclosure. The main difference between the wet blast cabinet and the dry blast cabinet is that there is no water used in the dry blast cabinet. The used media is collected by a heavy-duty dust extractor and collection hopper that is attached to the dry blast cabinet. You can use a dry blast cabinet for stripping the surfaces with old paint, coating, and rust and creating the required anchored profile. However, if you need a smooth surface finish, the dry-blasted components need to be polished after taking them out of the dry-blast cabinet.
3. Working of a wet blast cabinet.
The wet blast cabinet is constructed from high-grade stainless steel for long and rust-free working life. The bottom portion of the cabinet is shaped like a hopper and holds the slurry. The key features of a wet blast cabinet are:
- The heart of a wet blast cabinet is the robust and efficient slurry pump that provides the power you need for wet blasting.
- Precision and easy-to-use controls allow you to select the right blast pressure for blasting more delicate items.
- Large viewing panel with wiper and screen water wash.
- Large extraction fan to clear vapor and provide clear visibility
- High illumination LED lights for good visibility.
- Water wash down.
- Interior rubber lining.
- Separate controls for slurry pump, LED lights, and extraction fan.
- Door with safety interlock system for easy loading and unloading of parts.
- Quick release pump.
Working of the wet blast cabinet: The operator selects the required abrasive media, opens the grate of the hopper, and pours the abrasive media into the hopper. Refer to the product manual for the minimum and maximum quantity of abrasive media that can be added to the wet blast cabinet. Fill the water to the specified level and close the grate.
The operator places the component to be wet blasted in the cabinet and firmly closes the door. During wet blasting, the slurry is pumped into the blast gun and the compressed air entering the blast gun propels the slurry onto the blasting surface. The operator points the blast gun toward the surfaces and operates the foot pedal to propel the abrasive media onto the surface.
The concentration of the abrasive media: The concentration of the abrasive media in the slurry differs from one application to another application and the content of abrasive media in the slurry can range from 10 to 40% by volume. You have to establish the correct level of abrasive media concentration by doing one or more trials.
During the wet blasting process in the blasting cabinet, the abrasive media wears out and become smaller and smaller. The abrasive media which is not useful has to be removed and fresh abrasive media is to be added in its place to keep up the concentration level. The proven level of concentration should be maintained within a strict tolerance to achieve consistent results. The maintenance of concentration in the slurry can be done manually or there can be an automatic system.
4. Advantages of a wet blast cabinet.
- In a wet blast cabinet, the water in the slurry suppresses the dust and hence a dust collector is not required. However, a wet blast cabinet is fitted with an extractor fan to take away the mist produced during blasting.
- A wet blast cabinet can strip or clean the surface to remove paint, rust, coatings, oxidation, grease, or other contaminants and give the surface the required finish or anchor profile in one cycle.
- The low blasting velocity and good visibility of the blasting process in a wet blast cabinet give the operator better control over the blasting work and surface quality.
- The gentle and smooth blasting in a wet blast cabinet preserves the geometric and dimensional accuracy of the critical components and preserves the surface accuracy.
- The spray of the slurry that comes out from the blasting gun is even and ensures the components blasted in a wet blast cabinet have an evenly treated surface and a consistent anchor profile. There is no aggressiveness or harshness in the blasting method used by a wet blast cabinet.
- When using a wet blast cabinet, you need not worry about the impregnation of the abrasive media particles into the component surface since the water in the slurry flushes out the abrasive media during blasting.
- The presence of water in the blasting abrasive media in a wet blast cabinet eliminates the risk of frictional heat and spark due to the friction between the abrasive media and the blasting surface.
- The wet blast cabinet works quietly at a much lower decibel and does not disturb the nearby workers.
- The slurry used in a wet blast cabinet causes low wear and tear and the result is the life of the consumable parts like the nozzle and hose is 7 to 8 times more compared to those in a dry blast cabinet. The rubber gloves used in a wet blast cabinet have a good life.
- The consumption of abrasive media in a wet blast cabinet is less compared to a dry blast cabinet.
- The presence of water in the slurry makes reclaiming the used abrasive media easy.
- A dry blast cabinet is normally built bigger for easy management of dust, whereas a wet blasting cabinet is more compact for handling the same sizes of components. This saves you space.
5. Different abrasive media that can be used in a wet blast cabinet.
The different abrasive media that you normally use in a wet blast cabinet are garnet (Almandine and Alluvial), glass bead, aluminum oxide, crushed glass, and soda bi-carbonate
Garnet (Almandine and Alluvial): Garnet is a type of gemstone and has good natural abrasive properties. Garnet has a sub-angular shape, Mohs hardness number 7 to 7.5, comes in different grit sizes and it can remove coatings, old paint, rust, and mill scale from metal surfaces and can work on hard metals also. The coarser grit is suitable for working on aluminum, steel, stainless steel, and other metals and finer grit is suitable for materials like fiberglass. Garnet can quickly work through coatings and contaminants.
Crushed glass: Crushed glass has Mohs number of 5.5 to 7 and is good for wet blasting aluminum and steel. The crushed glass has an angular shape and forms a sharp anchor profile; however, selecting a proper grit size and blasting velocity can give you the required anchor profile/finish.
The advantage of crushed glass is it is a recycled material (environmentally friendly), cheap, and effective for many works. Crushed glass can be an economical media for the wet blasting of components like alloy wheels.
Glass beads: A glass bead media consists of spherical glass particles and leaves a fine and polished finish on the blasted surface. The Mohs hardness of glass beads ranges from 5.5 to 6 and the particle size can be coarse to fine.
The glass beads have a smooth surface all over and are safe for blasting soft and delicate materials. Glass beads are very popular for wet blast cabinets and by varying the blasting velocity a smooth anchored profile can be achieved.
Aluminum oxide: The aluminum oxide has angular shaped particles; a Mohs hardness of 8 to 9 and the grit size of this media can be coarse to fine depending on the need.
By varying the grit size and blasting velocity, aluminum oxide can be used for wet blasting hard metals (even with thin sections) and this is a good media for tough cleaning, extracting paint, coating, and rust. This is useful for finishing and edge rounding of surfaces. The high recyclability of aluminum oxide makes it an affordable media.
Soda bi-carbonate: The soda bi-carbonate used for wet blasting is not the baking soda used in our kitchen. There are companies like Armex and Natrium that manufacture a variety of soda bi-carbonates specifically for the soda blasting process. The size of soda bi-carbonate particles may vary from 70 to 270 microns. Soda bi-carbonate is not an abrasive material and hence it cannot be used for surface profiling. Soda bi-carbonate is used as a media when the surface needs a smooth finish without any profile.
However, you have to choose one abrasive media over another based on the existing surface condition of the component to be wet blasted in the cabinet and the expected finish after wet blasting.
6. Facilities required for installing a wet blast cabinet
A wet blast cabinet needs a power supply (typically three-phase power), water, and compressed air for its operation, and space for its installation. Most wet blast cabinets require a 40-50 CFM compressor capable of generating 60-70 PSI.
Power supply: Ensure you have the required power supply to run the wet blast cabinet and the compressor.
Water: It is recommended to use clear mains water or an alternative source that is free of minerals, salt, and dirt.
The PH (Potential of Hydrogen) is a measure of how acidic or basic the water is and the water we source from the mains has a PH value of 7 which is considered neutral. Water with a PH value of above or below 7 can stain the wet blasted surfaces. Test your water for PH value, and if the PH is above or below 7, discuss with your local chemist to solve the problem.
7. What size of wet blast cabinet is suitable for you?
The size of the wet blast cabinet suitable for your work depends on the components you propose to wet blast and their shape and sizes. Measure the size (length × breadth × height) of the largest component you want to wet blast and the size of the wet blast cabinet can be based on this component size.
Send an inquiry to Quantum Blast Technologies.
Send an e-mail to Quantum Blast Technologies with details of the components to be wet blasted, the maximum size of the component to be wet blasted, details of finishes required, application of the components, and request for the visit of their representative.
Have a detailed techno-commercial discussion with Quantum Blast representatives.
Depending on the type of components to be wet blasted you may need one or more of the fixtures viz. special swing arms (for easy manipulating of parts like alloy wheels), a turn table, baskets (for small components), and other fixtures. The addition of such fixtures will make the wet blast cabinet more versatile and productive, however, it increases the cost of the wet blast cabinet.
8. Final word
A wet blast cabinet is a highly versatile piece of equipment that has wide applications and can provide a range of finishes to a variety of surfaces and components.
For more information on wet blast cabinets please visit Quantum Blast
Phone: 1300822569 E-Mail: sales@quantumblast.com.au
