An abrasive container (i.e., blasting pot), a propelling mechanism, and a sand blasting nozzle or nozzles are commonly included in abrasive sand blasting machine in India. The specific equipment utilized is heavily influenced by the application and type(s) of abrasive(s).
Choosing the best blast nozzle for each application is as simple as understanding the factors that influence cleaning performance and work costs. For optimal cost/performance, four basic issues must be answered.
The nozzle chosen for the work is perhaps the most important factor in meeting production targets. The bore shape of the nozzle dictates the blast pattern required for the application.
- Straight bore nozzles produce a tight blast pattern, making them suitable for blasting tiny areas.
- Venturi bore nozzles produce a broad blast pattern and improve particle velocity, resulting in increased productivity when blasting bigger areas.
Venturi pressure blast nozzles are commonly utilized. They are built with a distinct internal shape to achieve various goals.
SBM venturi-shaped nozzles gradually taper outward from the opening to the nozzle's exit end. This progressive exit expansion allows for the mixing of air and media within the nozzle, causing them to expand equally before exiting. A venturi nozzle has a broad design that provides great peening intensity and cleaning capability. The performance of the venturi nozzle is determined by a proper length-to-orifice-size ratio, as well as entry and exit tapers. This design generates a huge blast pattern, resulting in maximum cleaning acceleration.
More air and media are permitted to pass through the orifice as nozzles wear from continual exposure to high-velocity media. The increased area within the nozzle consumes more air volume, putting more strain on the compressed air source. Unless air volume can keep up with the increasing flow, pressure at the nozzle will drop. Reduced pressure reduces peening intensity, productivity, and efficiency. To ensure continuing high output, a good rule of thumb is to replace the nozzle when the orifice wears to the next bigger size.
Types of Sand Blasting Nozzle
Straight Bore Nozzle
Straight Bore sand blasting nozzles produce a tight blast pattern, which is ideal for spot blasting or blast cabinet work. These are ideal for smaller jobs including cleaning parts, shaping weld seams, cleaning handrails, steps, grillwork, and carving stone and other materials.
Venturi Bore Nozzle
Venturi bore sand blasting nozzles produce a broad blast pattern while increasing abrasive velocity by up to 100% for a given pressure. When blasting larger surfaces, venturi nozzles are the ideal solution for increased productivity. Long venturi-style nozzles, such as blasting nozzles, can boost productivity by 40% when compared to straight bore nozzles, while abrasive consumption can be reduced by 40%.
Double Venturi Sand Blasting Nozzle
The double venturi type is represented by two nozzles in sequence with a gap and holes in between to allow ambient air to enter the downstream segment of the nozzle. The exit end is also wider than a standard nozzle. Both changes are aimed to improve the size of the blast pattern while minimizing abrasive velocity loss.
Wide Throat Nozzle
Wide throat nozzles have a big divergent output bore and a large input throat. When used in conjunction with the same sized hose, they can provide a 15% improvement in productivity versus nozzles with smaller throats. Wide throat nozzles with broader diverging exit bores can be utilized at greater pressures to produce a 60% larger pattern with less abrasive use.
Sand Blasting Nozzle Selection
Angle nozzles are also useful for getting into tight spaces such as the bride lattice, behind flanges, or inside pipes. Many operators squander abrasive and time waiting for ricochet to finish the work. The short amount of time required to change to an angle nozzle is always quickly recovered, and the total time on the job is reduced.
As a rule of thumb, the air supply system should be capable of providing at least 50% more air volume (cfm) than a new nozzle would require to create the required operating blasting pressure, whether that is 100 psi or 140 psi. This ensures that a nozzle can continue to perform well even after it has become slightly worn. However, excessive wear should be avoided or productivity will suffer significantly.
Remember that the nozzle entry throat must be the same size as the inside diameter of your air supply hose. Wear points, pressure decrease, and excessive internal turbulence can all result from the wrong size combination.
What are the Various Nozzle Material Options?
The nozzle material you choose is determined by the abrasive you use, how frequently you blast, the size of the project, and the rigors of the job site. Here are some broad principles for using diverse materials.
Aluminum Oxide "Alumina" (Ceramic) Nozzles have a longer service life and are less expensive than other materials. They are an excellent solution for low-volume applications where unit price is the most essential consideration and nozzle life is secondary.
Tungsten Carbide Nozzle
Tungsten Carbide Nozzle provide extended life and cost savings when harsh handling is unavoidable when mineral or coal slag abrasives are utilized. Not all tungsten carbide sand blasting nozzles are created equal. Kennametal nozzles are made of high-quality materials and are built to last.
Boron Carbide Nozzle
Boron Carbide Sand Blasting Nozzles have a long life and can be used with both air and abrasives. Boron carbide is appropriate for aggressive abrasives like aluminum oxide and some mineral aggregates when rough handling is avoided. Boron carbide Nozzle often outlasts tungsten carbide by a factor of five to ten.
