Jul 31 2006
The Foxboro Measurements & Instruments Division of Invensys (www.foxboro.com/instrumentation) has provided a solution for Calzin, Inc.’s sticky rubber situation. Calzin, an international supplier of coatings for the rubber industry, now offers Foxboro conductivity sensing technology as part of a measurement system that helps ensure customers get consistent product quality, as well as reducing their labor and materials costs.
For instance, if your target is a mixture of three percent solids, a two percent mixture will result in the rubber sticking to itself and may require rework. A four percent ratio can cause rubber sheets to slide off of pallets and possibly result in scrap. Worse yet, the excess can become airborne resulting in severe dust problems that endanger workers
Without a properly mixed antitack additive, rubber production can indeed be a sticky situation. Too little calcium stearate powder, the main ingredient of the antitack liquid additive, and rubber sheets could adhere to each other; creating costly rework to bring them back into spec. Too much calcium stearate and sheets could slide off of pallets and end up in the scrap pile. Despite the fact that variations in the mixture have tremendous implications for labor and material costs, as well as product quality, rubber producers have relied on human judgment to develop antitack mixtures that work for their products.
Recently, however, Calzin has produced a measuring system that enables its customers to determine the exact proportions of calcium stearate concentrate and water for their application. Calzin ships the calcium stearate to customers as a concentrated dispersion, and they in turn dilute it with water for use as needed. Through what has largely been trial and error, customer technicians adjust the flow of water into the premix concentrate until they feel it has the right consistency.
"This is far from an exact science. There’s a fine line between hitting or missing the proper ratio," says Jeff Blanchard, vice president at Calzin, Inc. "For instance, if your target is a mixture of three percent solids, a two percent mixture will result in the rubber sticking to itself and may require rework. A four percent ratio can cause rubber sheets to slide off of pallets and possibly result in scrap. Worse yet, the excess can become airborne resulting in severe dust problems that endanger workers," says Blanchard.
Seeking to help customers make more effective use of his product, Blanchard set out to develop an automated mixing system to remove the guess work and help his customers achieve consistent and repeatable release agent mixes. Figuring that determining the exact percent of solids ratio in the solution would provide a much more accurate and consistent solution, he hypothesized that conductivity sensing could deliver that information. His Internet search for authorities on the subject led him to the Foxboro Measurements & Instruments Division of Invensys Process Systems. After preliminary discussions about his application, Blanchard met with Foxboro process measurement experts, who demonstrated an electrodeless conductivity system, with which he could measure and maintain percent solids ratios with high accuracy. "The Foxboro solution measures and maintains a predetermined percent solids ratio based on conductivity, which assures accurate batch composition every time," says Blanchard.
The Foxboro system consists of a conductivity analyzer with a tailored custom curve set, and electrodeless conductivity sensor. The sensor measures the conductivity and sends a reading to the analyzer. From there, the software triggers alarms when conductivity setpoints are reached, which control a series of valves and pumps that supply the Calzin concentrate and water in proportion to maintain a predetermined target conductivity setting.
"The key was converting conductivity measurements into discernable information that technicians could understand. Through trial and error I developed a percent ratio chart as a guide for determining percent solids at different temperatures," says Blanchard. "Conductivity is not the easiest thing to work with. It can be very temperamental. But Foxboro supplied a complete solution, including technical support that made it possible. If I had a question, Foxboro was always there to help."
By automating the release agent mixing process, Calzin has improved the use of its additives, while assisting customers in reducing labor and material costs. "The most significant benefit for our customers is ease of use of our agents," says Blanchard. "They love it because we give them a quality concentrate and the capability to automate mixing specifically for their applications."
The automated system also reduces labor and material costs for Calzin customers. "In some cases there have been as many as six people checking and adding to the release agent mixtures. Our system totally eliminates the ‘too-many-cooks’ problem through automation. It eliminates human error while enabling customers to use just the right amount of concentrate, which also reduces waste. The Foxboro-based system enables us to better serve our customers and gives us a competitive edge in the market place," says Blanchard.