Pigment residues are generally left on the surface of objects. Sand blasting or glass bead blasting is effective for removing powder coatings, but it can still cause damage to soft metal surfaces such as aluminum.
The most advanced method of removing cured powder coatings is the use of plastic blasting media (PMB). Recycled plastic media produces only a small amount of dry residue and can be used for more than eight years, mainly for stripping paint on aircraft and aviation parts.
The plastic particles used in plastic blasting are harder than the paint film, but softer than the substrate, and the hardness range is 3-4 Mohs hardness. The Mohs hardness of a typical blasted abrasive is about 7. This plastic media has a pneumatic application range of 200-400 pounds per hour and pressures of 20-40 pounds per square inch. The nozzle is applied 0.5-1.5 feet away from the object. That is, in the sand blasting process, the volume is about 1000 pounds per hour, the pressure is 100 pounds per square inch, and the distance between the nozzle and the object is 3-4 feet. Powder coatings that can be effectively cleaned with plastic blasting media include electrical appliances, industrial machinery, storage tanks, vehicles and parts, aviation installations, military installations, building materials, shelves, furniture and vending machines.
When using plastic blasting media, some changes need to be determined, such as the blasting pressure, the angle of the nozzle and the substrate, the flow rate of the plastic medium, the residence time, the size of the nozzle, the distance between the nozzle and the part, and the type of coating , Substrate material and thickness, type and size of blasting medium, media pollution control, including pre-cleaning of parts, uniform coarse sand particle distribution (media supplement), shielding requirements and type of blasting equipment. These construction parameters are generally determined by equipment and media suppliers based on their past experience. The prior art equipment is suitable for using plastic media, and the basic feature is the electronic remote-control nozzle, which adjusts the air pressure of sand blasting and the flow of media from one substrate to another. Plastic sand blasting equipment also has other features, that is, the medium can be recovered by a precision cyclone equipped with low horsepower fans and motors. These separators can effectively remove all paint film residues and plastic media debris, and the media can be recycled and reused more than 30 times or more, with a media usage rate of about 9 pounds per hour.