A tier 2 automotive company makes small metal boxes with a process which includes laser welding and a vision inspection system. The machine was programmed to weld different components onto the metal enclosure. During the welding operation, an optical sensor would check the quality of the welds. The vision system used a lens to protect the sensor from welding slag and debris. After a few operations, they started seeing false positives in the welding areas, and the metal enclosure would be flagged for rejection. In investigating the issue, they found that the lens was getting dirty from the welding operation. Because of the sensitivity of the sensor, it would detect the debris and marks on the lens and signal for poor weld. The lens was doing its part in protecting the sensor from damage; but, they needed a way to shield the lens from dirt and slag during the welding operation and visual inspection.
With this process, the machine would weld metal fasteners onto an enclosure by laser. The optical sensor would move along the welded areas to check the quality. In a lead/lag operation, the vision system would check the welds after a few seconds of cooling. So, both operations were occurring at the same time but at different intervals. When they started to see the rejection rate increase, they would have to stop the operation, clean the lens, and verify the integrity of the welds. In some cases, they would have to replace the 1 ¼” diameter lens especially if a piece of welding slag marred the surface. With incorrect rejections and lens cleaning, downtime was hurting their production rates and cost.
This customer wanted to use compressed air because it is a powerful and invisible way to create a shield. Since EXAIR is a leader in efficient and effective ways to use compressed air, they contacted us for help. Initially, I suggested a Super Air Knife to deflect any slag and debris from the lens surface. I showed a prior solution to a very similar issue; “Air Shielding a Laser Lens” (Reference below). But, because of the proximity to the part and the limitation in space, the Super Air Knife configuration in the solution below would make it impossible to use. They were looking for a product that could be mounted either flush or behind the surface of the lens and still protect it.
To accommodate for this request, we had to direct the compressed air stream at an angle. EXAIR manufacturers a product that can do just that, the Super Air Wipe. The design of the Super Air Wipe blows compressed air at a 30-degree angle toward the center in a 360-degree air pattern, just like a cone. It can be placed around the lens and still be able to create a “wall” of air to block any slag or debris from hitting the lens.
I recommended the model 2452SS, 2” Super Air Wipe Kit. This Super Air Wipe has the body, braided hose, hardware, and shims that is made from stainless steel. It can handle the high heat loads from the welding process as well as to allow for easy cleanup after a day of operating. The kit includes a filter, to keep the compressed air clean; a regulator, to finely tune the force requirement; and a shim set. The shim set includes two additional sets of shims that can be added to increase the force of protection if needed. With the kit, the customer can “dial” in the correct amount of force needed to keep the lens clean without using excessive amount of compressed air.
As an added benefit of saving compressed air, the Super Air Wipe uses the Coanda effect to maximize the entrainment of ambient air into the compressed air stream. This makes the unit very efficient and very powerful. The Super Air Wipe was mounted just behind the lens like the customer required (Reference mock picture below), and the sensor could examine the welds without any interference with the metal enclosure.
Visual inspections systems are highly accurate pieces of equipment, and a dirty lens will affect the performance. EXAIR has many ways to keep the lens clean with a non-contact invisible barrier to protect sensors, cameras, and lasers. If you have a similar application, you can contact an Application Engineer to determine the best way to keep the lens clean and your equipment functional. After mounting the Super Air Wipe, the customer above eliminated any false rejections, and dramatically decreased any downtime for cleaning or replacing the lens in his welding machine.
John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb
