R&D / Leverage™, a specialist in tooling for injection stretch blow molding of PET bottles, reports that a switch from desiccant dryers to vacuum dryers has solved multiple problems, not least of which is the sheer length of time that desiccant systems need to dry polymer.
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After R&D / Leverage replaced desiccant dryers on seven Nissei ASB and Aoki injection stretch blow molding lines with LPD™ vacuum dryers from Maguire Products, Inc., the savings in time were dramatic, according to Alan Tolley, managing director.
“While the desiccant dryers needed four to six hours to dry material, the LPD dryers take only one hour and twenty minutes from a cold startup,” said Mr. Tolley, “and in subsequent drying cycles this is reduced to forty minutes.”
Besides startups, the desiccant dryers also posed problems with job changeovers. R&D / Leverage builds single-cavity “pilot” tools for making samples, plus multi-cavity tools for commercial-scale operation. The tools undergo trial runs on the seven injection stretch blow lines, which process at rates up to 70 kg/h. R&D / Leverage typically has five or six tool changes per week.
“The LPD dryers give us much more flexibility when testing different grades of resin on one tool,” said Mr. Tolley. “Because we are not a production-scale facility with long product runs, the desiccant dryers were always a challenge for us, posing problems with getting the material dried properly. The worst thing was to be held up by drying issues while we had customer visitors on site who came from as far away as China or South America.”
Other advantages of the LPD dryers cited by Mr. Tolley include improved resin filtration, which provides enhanced bottle clarity due to less contamination, and more flexible throughput control for the single-cavity pilot tool versus high-cavitation production tools.
Along with the seven LPD dryers, R&D / Leverage installed a central Maguire® Weigh Scale Blender, which is important because the industry now requires incorporating more recycled material. The blender delivers to the molding process precisely controlled batches of virgin and recycled polymer, colorants, and additives. Most customers ship their own material to R&D Leverage for use in producing sample bottles. The company uses up to ten different colors at varying percentages.
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Because the LPD vacuum dryers dry more quickly and efficiently than desiccant dryers, they impose less stress on the material and less heat history. “The vacuum dryers provide absolutely more stable material,” said Mr. Tolley. “In the past we were forever having to change desiccant every six months because we were doing so much stopping and starting of our molding processes. That meant added cost and added maintenance.”
Even with the considerable advantages cited by R&D / Leverage for vacuum drying, the number one reason for switching from desiccant systems may well be energy savings, according to Paul Edmondson, managing director of Maguire Europe.
“Considering that drying polymer can account for 15% of the total process energy of a molding operation, a compelling reason for using vacuum dryers is that they consume up to 80% less energy than desiccant systems,” said Mr. Edmondson. “While the example of R&D / Leverage demonstrates that the speed and quality of vacuum drying can enable toolmakers and laboratories to make enormous gains in productivity, the advantages over desiccant systems are also available to processors in full-scale production. Vacuum drying has the potential to be the dominant means of drying polymer, because energy savings and increased productivity will always be in demand.”
Since introducing vacuum drying to the plastics processing industry in 2000, Maguire has shipped more than 2,500 dryers. In addition to the LPD dryer, the company offers the VBD™ vacuum dryer. Both systems are available worldwide and are covered with a five-year warranty.
About R&D / Leverage
The European operation of R&D / Leverage is the world’s leading supplier of single-stage tooling for injection stretch blow molding of bottles, serving all major brands in the food and beverage, personal care, and healthcare markets. The company’s Product Solutions Laboratory at Sutton in Ashfield, Nottinghamshire, UK provides sampling, tool development, and customer training. The global toolmaking business of R&D / Leverage is headquartered at Lee’s Summit, Missouri, USA.
About Maguire
MAGUIRE PRODUCTS, INC., headquartered in Aston, Pennsylvania, U.S.A., is the world’s largest supplier of gravimetric blenders, liquid color pumps, and vacuum dryers and also manufactures loading systems, auger feeders, granulators and related equipment and software. Its customers include injection, blow, and rotational molders, extrusion processors, and compounders. Founded in 1977, Maguire operates six manufacturing facilities in Aston. The company maintains a network of distributors in the Americas and overseas and has three sales and service subsidiaries that stock, sell, and service auxiliary equipment systems from Maguire and its affiliate, Novatec, Inc.: Maguire Canada, Maguire Europe, Maguire Asia, and Maguire IMEA.
