By Tony Ring, technical director Fielco Adhesives. Huntingdon Valley, PA
Every modern lab uses specialized instruments to ensure product quality and consistency. However, the right instruments are also critical for solving important questions about day-to-day customer production operations, including assembly line snags and unusual applications. In this series of articles (others scheduled for June and October) we’ll discuss both the general use of instruments, as well as ways they solve our customers’ questions.
The Brookfield cone-plate digital rheometer is an integral part of quality control testing (and also developmental testing) of very thick materials, such as Fielco’s Masterweld 6300 epoxy. Fielco uses this instrument to determine the viscosity of fluid materials, which is a measurement of resistance to a liquid’s flow. This measure is critical when designing the right piping and dispensing equipment for specialty materials. For instance, if a material is too thin, the dispensing equipment may not be able to control the correct flow during operation, which could result in excessive adhesive use and waste. If a material is too thick, dispensing equipment may not be able to dispense transport the material at all.
We test sample materials in the digital rheometer at elevated temperatures to simulate customer-processing techniques. It’s also used to investigate shear-dependent behavior that could interfere with a customer’s specific application needs. The instrument was recently used to diagnose a pumping problem experienced by a customer using an adhesive. The material showed an exact match with a standard spindle viscometer, but showed a higher viscosity when tested with the digital rheometer due to a slight shear-induced thickening mechanism in the formula. With the enhanced data, the customer was able to modify the dispensing technique slightly and solve the problem.
The Aquastar titrator is used for moisture analysis on raw materials for polyurethane products. Very low moisture levels are needed to maintain material properties and reactivity. The instrument allows us to be sure of product shelf life in unopened pails, which is a critical point for inventory control (especially important for manufacturing environments where aspects of the process are not readily adaptable to just-in-time procedures). It’s also used to test raw materials requiring very low levels of water, including polyurethane adhesives and sealants and acid-cured epoxies. This titrator would be used to maintain product consistency by regulating water content in solvents and absorbed-on fillers.
Fielco regularly uses this instrument to resolve customer materials problems and other materials concerns. We recently received some inorganic filler that caused a change in viscosity of our finished product and found that a batch adjustment was required to bring the formulation back within specification. In this instance, we tracked the problem to higher-than-normal moisture content of the filler. In another example, a customer was experiencing problems with microbubbles in their cured urethane casting for electronics. Fielco determined that there was moisture in the B side (which contains a hydroscopic polyol material) of their urethane system. It turns out that their nitrogen purging system had failed when their gas cylinders were emptied during the manufacturing process.
Quality control never ends with just the production of a specialized material; it continues through the entire use cycle of a product, which is why Fielco invests in measurement instruments for the lab – and beyond.
For more information please contact Fielco at 215-674-8700 or visit our web site at http://www.fielco.com
REPRINTED FROM ADHESIVES AGE, MARCH 1998