Powder Coated Tough - Fall/Winter 2007 - (Page 32) Powder Automation synchronized with the product carrier. Multiple style recipes are stored in the PLC and are entered through the operator interface. It is not unusual for a system to have over 100 styles available. A typical issue with triggering a gun off is the residual powder that remains in the powder hose. When the gun is triggered on again, this residual powder can “snowball” and create an initial surge of powder from the gun, rather than a smooth pattern. Purging the gun immediately after a trigger cycle clears this powder from the hose. When the PLC triggers the gun off, it also turns on a secondary air source to the powder lift tube pump. This air is applied only to the supplementary port on the pump and not to the conveying port. As a result, air is flowing through the powder hose without creating the venturi required to lift powder from the hopper. This prevents the residual powder from settling in the powder hose, which in turn prevents the “snowball” effect. The amount of time that this purge air is applied is adjustable through the operator interface. More time may be required for longer hose lengths. If a gun needs to be triggered while it is purging, the purge cycle is canceled and normal triggering resumes. Advances in powder gun control units provide users with additional flexibility in automatic triggering. Duallevel powder output controls can be used to select between two separate preset powder flow levels. The levels can be selected based on the product being coated. Incorporating dual-level powder output with a style based triggering system is the most common usage. More recently, analog gun control units have become available. These units allow a PLC to control the powder air controls and/or the kV settings across the range of the gun control unit. This can be highly effective in a style-based system with a high number of different styles. Powder output and kV can be altered by the PLC as the product passes the powder gun. Reducing edge build and reinforcing other areas are the primary uses for this method. Powder outputs and kV can also be automatically adjusted based on formulas applied to variables within the system. U n l o c k t h e Va l u e o f PCI MEMBERSHIP The Powder Coating Institute is dedicated to growing the powder coating market so all of its members benefit. Do you: ✓ Use powder coatings? ✓ Make powder coatings? ✓ Make pretreatment, application or curing equipment for powder coatings? If the answer is YES to any one of these questions, then you need to discover the value of PCI membership! What you'll get: ● ● ● ● ● ● Discounts for exhibiting at PCI shows Discounts on advertising in Powder Coated Tough A listing and hot link on PCI's web site, which generates half a million hits per month! Additional exposure to current and potential customers Free technical material Ongoing education and networking opportunities Don't wait, call or visit PCI today to join more than 320 other powder coating businesses who will help keep you in the forefront of the industry. Click on www.powdercoating.org or call PCI at 1-800-988-COAT 32 Powder Coated Tough http://www.powdercoating.org http://www.powdercoating.org
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