What's New » DÜSSELDORF - Maguire expands capacity to build LPD™ Dryer amidst global boom in sales of this unique vacuum-based system

DÜSSELDORF - Maguire expands capacity to build LPD™ Dryer amidst global boom in sales of this unique vacuum-based system

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DÜSSELDORF, October 20, 2004 - Sales of the world's only vacuum resin dryer designed for plastics processors have already reached 800 units and are now growing so rapidly that Maguire Products, Inc. has expanded production capacity for the system by one-third, the company announced at K 2004 (Hall 4, Stand 4C05). Maguire is adding 700 m2 (7,500 sq.ft.) to its dryer production facility in Aston, PA, U.S.A.

Key to the success of Maguire's LPD™ dryer is the far greater speed and efficiency with which it dries resin, said B. Patrick (Pat) Smith, vice president of marketing and sales: "After Maguire introduced the LPD™ dryer in 2000 as a fundamental departure from hot air and desiccant dryers, it took three more years for a significant number of processors to prove for themselves that this system actually does require only one-sixth of the time and 20% of the energy to dry resin properly, and that it substantially reduces heat history and cold-startup time."

Typical of the productivity gained by switching from conventional to Maguire LPD dryers is the experience of an Italian manufacturer of injection blow molded PET bottles for cosmetic packaging. A member of the global Alcan group (www.alcan.com), this company reported that it reduced Monday-morning cold startup time by four hours, bringing resin to the target level of dryness in just 40 minutes and at a drying temperature of only 150 °C, compared with 6 hours at 180 ° with a desiccant dryer. The reduction in startup added 7.5% more production time, or 70,000 more bottles per month. 

Another example, focusing on productivity gained through increased drying efficiency and reduced heat history, comes from Melet Plastics Inc., a custom injection molder in Winnipeg, Manitoba, Canada (www.meletplastics.com). "We used to have problems molding glass-filled nylon parts that require a total absence of humidity," said the company's Tony Melendez. "With Maguire's LPD dryer, our percentage of rejects went from 25% to 1%." 

Other advantages of vacuum drying have become evident, according to Maguire's Pat Smith, in several common applications that pose special challenges to conventional dryers:

  • Environments with high relative humidity. Desiccant dryers used under conditions of high relative humidity work extra hard because they must remove moisture from ambient air as well as from resin. "Many processors are well aware of the problem of increased reject rates resulting from resin dried improperly under conditions of high relative humidity," Smith said. "But since a vacuum dryer by definition eliminates ambient air from the drying canister, ambient conditions have no effect on the drying process."
    This advantage is illustrated by a recent comparison of desiccant and vacuum systems in actual production runs by a molder of acrylic automotive parts (see table). Besides drying the resin both more quickly and more thoroughly, the LPD dryer continued to dry at peak efficiency even as the moisture level in resin dropped substantially, becoming closer to that of ambient air. 
  • Materials with high moisture content. In the rapidly growing field of plastics / wood-fiber composites, moisture levels of wood flour can range from 3 or 4% by weight to as much as 15%. "Desiccant dryers are very inefficient in handling composite wood flour pellets because the desiccant becomes saturated so quickly that the system cannot maintain air at the required low dew point," Smith said. "With a vacuum dryer, however, there is no desiccant, and wood flour typically dries properly in only about 40 minutes." 
  • Multiple short-run operations. Company laboratories that process test specimens, chips for color matching, or samples for customers are discovering that the short drying cycle of the LPD dryer enables them to increase their productivity substantially, Smith said. "A lab technician in a color house may need to do 20 or more color matches in a day, with multiple polymers," Smith noted. "Since the LPD dryer takes minutes instead of hours to dry these materials, the technician's output increases, along with the speed of response to customers."
  • Resins that can be embrittled by over-drying. When nylon is dried to a moisture level below 0.08%, it becomes brittle and produces serious defects in the finished product. Since a desiccant dryer running continuously will remove moisture until none at all is left, a prolongation of the drying cycle caused by a processing-machine stoppage can result in nylon that is over - dried. "This cannot happen with the LPD dryer," Smith said. "Because the vacuum in the drying canister is not quite at full vacuum and retains a thin atmosphere, there is always a bare minimum of moisture left in the system. The moisture levels inside and outside the resin pellets eventually reach equilibrium, and that proves to be at approximately 0.12%." 

    Unique Technology Is Key to Energy Savings, Speed of Drying, and Speed of Color Change
    The LPD dryer differs radically from conventional hot-air/desiccant dryers in two ways: 1) instead of flowing hot, dry air over the pellets to slowly draw the moisture out, the patented LPD dryer uses vacuum to reduce the boiling point of water, quickly turn the moisture into water vapor, and literally pull the water vapor from within the pellets; and 2) the LPD dryer carries out heating and vacuum drying simultaneously in separate stations, making possible small batches while in effect transforming a batch process into a continuous one that keeps pace with the throughput of the plastics processing machine.

The small batch size and short drying cycle of the LPD dryer make it possible to shorten Monday morning cold startups from several hours to less than an hour, adding that much more to weekly production time. Also increasing productivity is the three-station indexing system of the dryer, which makes possible color and material changes on the fly, eliminating downtime. 

Another source of cost savings is the elimination of desiccant, which, in a conventional dryer, becomes saturated and must be regenerated by a heating and cooling process so it will again be able to absorb moisture. The energy used in this process is lost to the ambient environment. In addition, desiccant degrades over time and must be replaced on a regular basis.


MAGUIRE PRODUCTS, INC., headquartered in Aston, Pennsylvania, U.S.A., is the world's largest supplier of gravimetric blenders and liquid color pumps and also manufactures loading systems, granulators, dryers, auger feeders, and related equipment and software. Its customers include injection, blow, and rotational molders, extrusion processors, and compounders. Founded in 1977, Maguire operates five manufacturing facilities in Aston and Smithfield, Rhode Island, U.S.A. The company maintains a network of distributors in the Americas and overseas and has two sales and service subsidiaries: Maguire Europe, which supports customers throughout Europe and operates a distribution center in Tamworth, Staffordshire, United Kingdom; and Singapore-based Maguire Asia, serves customers throughout South Asia and the Pacific Rim. Visit the Maguire Products web site: www.maguire.com