Sand blasting utilizes compressed air to accelerate a high-velocity stream of sand against surfaces for cleaning, finishing, etching, peening, and coating removal. It’s considered an abrasive sandblasting process.
While terminology varies, sand blasting refers specifically to sand media, while abrasive blasting covers all media types like steel, plastics, baking soda, walnut shells, etc. But how exactly does sand blasting work?
Sand Blasting Process Stages
Let’s look closer at the stages comprising the blasting process.
Compressed Air Supply
Sand blasting requires a constant, high-volume supply of compressed air, typically 60-150 PSI. Large compressors and receivers build a reservoir of pressurized air feeding the blasting nozzles.
Blasting Nozzle
The nozzle accelerates sand particles by injecting them into a stream of compressed air. Nozzle types and sizes differ based on the desired abrasive effect. The high-velocity sand stream exits the nozzle toward the work surface.
Sand Supply
Sand held in a pressure vessel feeds into the nozzle’s airstream at a controlled rate. Blaster models include pressurized floor pots, injector tanks, and cabinet hoppers to meter sand flow.
Part Handling
Components are mounted inside a sealed blasting enclosure and positioned in the path of the sand stream manually or by automated manipulators.
Sand Blasting
As air propels the sand stream against the part, the abrasive action strips coatings, smoothes surfaces, removes oxidation, profiles the substrate, or peens the surface, depending on the application goal.
Sand Recycling
The expended sand and particulates settle onto the floor inside the cabinet or room. Cyclone separators sift and reuse the bulk of the sand while waste gets captured by dust collectors.
Operator Controls
Skilled operators work from inside the enclosure or an attached control room, adjusting blasting intensity, positioning parts, and monitoring the process.
Post-Blast Finishing
After blasting, components get cleaned, inspected, masked, coated, packaged, or moved to the next production stage depending on requirements.
This overview covers the core steps, but variations exist across the many types of blasting equipment in use. Next let’s look at two main equipment categories – pot blasters and cabinet units.
Pot Blaster Process
In a pot blasting setup, the worker holds a blasting nozzle fed by sand hoses. The operator manipulates the nozzle by hand or machine arms while blasting parts positioned inside an enclosed space like a blast room. Sand and dust accumulate on the floor for recovery. This allows large-scale blasting but depends heavily on operator skill.
Blast Cabinet Process
Cabinet systems feature a contained workspace with glove ports for manual blasting of smaller parts. The operator reaches into the cabinet with abrasive-resistant gloves secured to port openings. Nozzle, viewing window, lighting, dust collector, and sand metering valve position strategically inside the workspace. Spent sand falls into a drawer for screening and reuse. This creates a compact, clean blasting station.
Conclusion
At its core, sand blasting simply utilizes compressed air for accelerating sand against surfaces to modify their properties. But effectively harnessing this abrasive interaction across various scales, materials, and environments while protecting workers requires in-depth training and specialized systems. Mastering control of the core blasting process is key.
