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Abrasive Blasting 101 | The Ultimate Resource
Regular nozzle maintenance on your siphon blast cabinet is a quick and easy way to save money by reducing production time and maintaining optimal productivity. How can something so simple make such a difference to your bottom line? Siphon machines are nozzle critical, meaning that the condition of the nozzle greatly impacts the productivity of the machine. This is because the abrasive’s velocity and direction are hugely dependent on a specific design formula for the compressed air being used as it relates to the size of the nozzle itself.
Real World Example
Wad up a small piece of paper to the size of a green pea and put it on a flat surface about 12 inches from your face. Pucker up like you’re going to whistle and blow at the paper pea. It probably moves away from you at a good speed. Repeat the same test but instead of blowing, yell the word “Holler” at the paper wad remembering to keep your mouth wide open. Why doesn’t the paper move? The velocity of the air exiting your mouth has changed based on the shape of your lips. As the siphon nozzle wears out, a similar situation happens.
It’s time to replace a siphon nozzle when it wears out, which is typically when the nozzle ID increases by 1/16″ its original size. You can purchase nozzles made from harder materials that will last longer. The least expensive nozzle is made from ceramic material, and these are usually used for non-cutting abrasives like glass beads and plastic. Using ceramic with any cutting abrasive is simply an exercise in daily nozzle replacement that isn’t really necessary. Tungsten carbide is a harder nozzle material that’s often used with glass beads to greatly reduce nozzle replacements. Unfortunately, hard material does not necessarily mean long lasting when it’s used with cutting abrasive like aluminum oxide and silicon carbide. Long lasting nozzles require that you eliminate as much friction as possible by having a smooth hard surface such as Boron Carbide nozzles, which have many trade names. Boron Carbide is light and feels like gray colored glass. If you wanted to make an entry shield for the space shuttle think Boron Carbide when you are trying to figure out why they last longer.
Pro Tip: If you find you are turning up the pressure to keep the same cleaning speeds you are either using a worn out nozzle that’s reducing abrasive velocity or worn out abrasive that is dull or smaller in size. If a hammer got just a bit smaller each time you hit a nail you would replace it often. Worn out sandpaper slows down so it needs to be replaced. Replace it with more expensive harder sandpaper and you end up with more production and quicker sanding. A worn out nozzle will also start delivering more abrasive out the nozzle. This reduces visibility inside the cabinet but more important you start blasting abrasive on top of abrasive and that can slow down cleaning.
As siphon nozzles wear out they widen and the abrasive velocity at any selected blasting pressure slows down. We are saying the abrasive velocity lessons and that means you have less frictional heat and it requires more and more time to complete projects. Additionally, the longer you run your machine, the more abrasive you use (recycle) and the quicker the abrasive wears out. Finally you may reach a point when you simply run out of compressed air and the ability to increase the standard blasting pressure is no longer an option. Keeping a quality nozzle that’s the right size for any injector siphon gun is important for maintaining faster cleaning speeds.
One last final piece of information, “a longer siphon nozzle and a longer gun barrel have something in common, can you tell us what?” We can! Hint, it has to due with velocity!
Pro Tip: We recommend keeping your nozzle within 1/16″ of its original inside hole size. This will save you time and abrasive, and maintain optimal production rates.
Do you have a Media Blast & Abrasive blasting cabinet? You can request information about parts right from our website to quickly replace your nozzle and start saving time and money. If you’re not sure which model you have, browse our machines here.
