Delivery of blast media to an individual part, or a continuous run of product is accomplished in a number of methods, each specifically chosen for the intended surface result, as well as the speed and cost of doing so.
Surface Blasting Systems has the experience to help you determine what media delivery is best suited for the surface results you are looking for.
A pressure blast system provides the highest intensity results of the 5 delivery methods. Compressed air and the blast media flow together through a heavy walled hose, and are accelerated through a smaller diameter blast nozzle to produce the desired blast results. Fine adjustment of air pressure, media size, shape & mass, flow rate, nozzle size & shape, and blast distance all combine for a specific desired result. Most types of blast media can be used with a pressure blast system.
The heart of a pressure system is the pressure pot, where media is combined with air and sent to the blast gun. The pot is replenished with media when the air pressure is bled off, then it builds back up to its working level. It is important to size the pressure pot for multiple blast cycles, if possible, to conserve compressed air.
Pressure blasting offers the fastest coverage of all, at over twice the rate of a suction system. The tradeoff for this speed is a bit more wear and tear on components, specifically blast hoses and nozzles, but routine maintenance keeps the machine running in peak form.
The suction method of blasting utilizes air pressure alone to draw media into its stream at the blast gun. This requires a second hose to supply the media, where it is literally pulled on an angle into the air flow, and propelled out of the nozzle. Again, most types of blast media can be used with suction. Adjusting the air pressure, media type & flow rate and nozzle size fine tune the blast results.
A suction system provides less blast intensity and lower surface coverage rate than the pressure blast method. However, no pressure pot is required, and the wear of hoses is greatly reduced. When production rates allows longer cycle times, often a suction blast option is chosen.
Wheel blast systems require blast media with a material density of steel or higher. The blast media is thrown from a centrifugal wheel to accelerate the blast media High blast intensities and high surface coverage rates are produced by the wheel blast systems.
Adjusting the wheel speed, media flow rate and BLAST MEDIA type will change the blast results.
Wet blast systems carry the blast media in water flowing through a blast hose, or introduced to an air blast stream at the nozzle. The impact of the blast media on to the part is limited by the speed of the water. The wet blast system provides the least blast intensity of the four types of blast systems, but offers minimal dust and better part impact control. Aluminum Oxide is often used in the wet blast system, however stainless steel shot may also be used for wet peening.
In some less common instances, a particular surface treatment requires a heavier media to impact the part or material at a slower but more uniform rate. This can be accomplished by dropping perfectly round steel shot, from a specified height, in a tight "curtain" that rains on the part as it passes below. This type of media delivery, and the unique surface specification requiring it, are seen mainly in aerospace.