A float glass company purchased an EXAIR model 110230 Super Air Knife kit to clean the surface of glass sheets. The production manager watched the video of the performance of the Super Air Knife, and he was amazed at the efficiency, effectiveness, and safety that they could provide. (We have many EXAIR Product videos here). After they received the Super Air Knife, they mounted it after the annealing process to remove any specks of dirt and debris prior to the final visual inspection. They were getting some false rejections from contamination that remained on the sheets, and they believed that they needed more force to better clean the surface of the glass.
The blowing system was operating at 73 PSIG (5 bar) air pressure, the maximum amount that could be supplied at the machine. With the dynamics of the Super Air Knife, the blowing force could be increased by changing the shim thickness. The plant manager contacted me about the characteristics in force and flow by changing from the standard 0.002” (0.05mm) thick shim to the 0.003” (0.08mm) or 0.004” (0.1mm) thick shim. (These shims are Included in the shim set for aluminum Super Air Knife kits along with a 0.001” (0.025mm) thick shim). As an Application Engineer at EXAIR, I was inquisitive about the application and wanted to do a “forensic” analysis of the system to generate the best suggestion. So, I had him send me pictures of their setup.
With non-conductive materials like glass and plastic, static can be a huge issue. Static forces can easily be generated and will cause dirt and debris to “stick” to a surface. This attraction is very strong and will make it very difficult to remove. If the static force can be neutralized, then the contamination can easily be removed from a non-conductive surface.
With this understanding, my initial suggestion for the company above was to remove the static charges from the surface of the glass with an EXAIR Static Eliminator. With the complimentary design of the Super Air Knife, it is simple to mount an Ionizing Bar directly to the Super Air Knife that they currently installed. I recommended a model 8030, 30” (762mm) long Gen4 Ionizing Bar, and a model 7960 Power Supply to transform the Super Air Knife into a Gen4 Super Ion Air Knife. The positive and negative ions that are generated by the Gen4 Ionizing Bar can be carried by the laminar air flow of the Super Air Knife to treat the surface. This combination can work well to remove static charges up to 20 feet (6m) away. Once the static is removed, the force of the air stream would easily remove any dust or debris from the glass surface.
As an added note from the picture above, I recommended a different position for the Super Air Knife, or soon to be Gen4 Super Ion Air Knife to optimize the blowing area. The glass company had the air knife positioned to blow straight across the surface of the glass. For proper cleaning and better contact time, I suggested to mount the Super Air Knife with the Ionizing Bar about 6” (152mm) above the surface of the glass and angle it to about 45 degrees. This would increase the contact angle and allow for a better blowing force to remove all the debris. By adding the Gen4 Ionizing Bar and adjusting the blowing angle, they were able to reduce the air pressure from 73 PISG (5 bar) to 30 PSIG (2 bar); saving compressed air and reducing false rejections.
Pictures are always helpful in analyzing an application. With the company above, we were able to optimize their cleaning process and reduce the total amount of compressed air required. If you find that you need more force to clean a non-conductive surface, EXAIR Static Eliminators will resolve these static problems. If you would like to discuss your application with an Application Engineer at EXAIR, we can go through the “forensics” analysis for optimization.