Choosing a blast nozzle is an important decision before you start working the media. Obviously you need to know about your air compressor and the strength of the nozzle to resist impact from compressed articles that emit out in pressure. A precise nozzle bore diameter will determine your forced capacity and impact.
After regular wear once the nozzle’s mouth increases, the size of its orifice will quadruple but then the air strength will be compromised and more media will be flushed out.
To get the best nozzle type, identify the nozzle pressure (PSI) you need to maintain for productive blasting and the air volume your compressor supplies per minute (CFM). But to maintain the nozzle size, the selection of a good built type can go in a longer run since abrasive from a lower quality nozzle will wear its inner lining away and lose vital volume pressure. Once pressure is lost, you get inadequate compression strength and an unimpressive result. Aptly, the maintenance of pressure is a must between the hose and the compressor.
A greater blast pattern will need increment in the nozzle size also. It means the bigger the nozzle, the more the blast pattern is to be. If there is adequate compression and the nozzle is narrow, it will produce a tight stream and a concentrated blast pattern upon impact. In a Venturi, there is convergence at entry and divergence at exit which ends up in larger blast pattern and uniform particle distribution.
For higher exit velocity, longer neck nozzles can be adapted. They produce a larger blast pattern and higher production rates. Moreover, the inner surface of a nozzle is equivalently vital to give long-lasting results.
The most important part: A nozzle is prone to tearing when friction rubs compressed particles from its passage. To reduce this suffering, the pertinent consideration is to know what material the nozzle is made of. The inner lining of the bore must be made of harder material so it can withstand friction for a prolonged time period. Basically nozzles are made of carbide which comes in 3 variations i.e. tungsten carbide, silicon carbide and boron carbide, all of which are cheap but have different degree of impact resistance. But for greater shock resistance, you may prefer composite carbide which is high in price yet impact endurance is greater. Being hard, such material also needs careful handling lest the inner casing will crack. Some types like boron carbide being very hard have above average durability can last up to 10 times than tungsten carbide. Composite carbide is even harder.
In a general sense, selection of abrasive and type of working are crucial points to decide which nozzle will suit the media though before going for a dry nozzle, try out vapor abrasive blasting which helps your nozzles to last up to 3 times longer than a dry one. Since a nozzle isn't so cheap to replace, wet blasting ones can be preferred due to their advantage over dry nozzles. In a wet blaster, there is a lubricating flow of water that avoids major friction between the media and the nozzle material, so it makes nozzle's life longer.
Waterjet cutting blaster also has control over its abrasive flow for high quality cutting. The Feedline V supplies the optimum flow of abrasive to the cutting head and saves material. It is an electronically controlled, motor driven system to ensuring constant flow of abrasive and hence, reduces abrasive consumption. The operator need not adjust any setting for other media as the correct abrasive flow is automatically set by the built-in process database. Changing abrasive flow is also automated, so the operator never forgets to adjust the abrasive when changing materials.
In case of a sandblaster, everything is manual and with a lesser range. It will also increase the consumption of media if we go up from a #6 to a #8 nozzle. We can learn that some vital factors like media feeding rate, air compression, type of nozzle and size, all affect final output utilization. An equilibrium value that gives a relative calculation between the feeding rate and productivity is always a part of consideration. After that value, abrasive wastage is tend to happen. So to attain this efficiency, we must know exactly how much production rate we need as this will determine us choose an appropriate nozzle. If we have the budget, composite carbide nozzle will be best so that we can cover our cost in the long run and get the utmost value from our nozzle.