What's New » Speed and Versatility of Vacuum Dryers Keep Molding Machines Up and Running in Mack's New Medical Cell

Speed and Versatility of Vacuum Dryers Keep Molding Machines Up and Running in Mack's New Medical Cell

Maguire® LPD™ Dryers Help Mack Molding Shorten Time for Product Changeovers

ARLINGTON, VT, U.S.A., June 10, 2008:  Mack Molding Co., one of North America’s premiere plastics processors, reports that the speed and versatility of Maguire® LPD™ vacuum resin dryers have helped maximize the productivity of the company’s new medical molding cell.

Based at Mack’s headquarters plant in Arlington, the molding cell is designed for short runs of prototypes, small-lot parts, and parts in multiple colors, noted Tom Revane, process engineering manager. The cell is equipped with five 40- to 100-ton injection molding machines, each served by a dedicated LPD vacuum dryer.

“As a medical market supplier, it’s important to maximize machine uptime for products that require frequent resin and tool changes,” Revane said. “Some of our customers’ products must be run in small batches of 100 parts or less, and in a multitude of colors. With an LPD dryer at each press, the resin for the next job is dry and ready for use by the time the new tool is set.”

The key to the versatility of the LPD dryer is its much shorter drying cycle and smaller batch size compared with conventional desiccant dryers, according to Mark Hamilton of Hamilton Plastics Equipment, LLC, a sales representative for Maguire. “The LPD system dries resin in only one-sixth of the time needed with conventional dryers—literally 40 minutes or less, instead of the four hours needed with a desiccant system,” Hamilton said. “And because the LPD dryer has a three-station indexing mechanism that supplies resin to the processing machine while another batch is being dried, it is possible to work with small batches yet still maintain a continuous process.”

When Hamilton first approached Mack Molding about the Maguire dryers, Tom Revane was skeptical. “Mark convinced us to use one dryer on a trial basis. Our first trial was with a polycarbonate resin with an initial moisture content of 0.24%. After 25 minutes in the dryer, moisture was reduced to 0.03%. When many more trials proved that the LPD dryer worked rapidly and consistently, we ordered one machine for each of the presses in our medical cell.”

A Preeminent Processor Is Now a Key Player in the Medical Market

A pioneer plastics processing firm founded in 1920, Mack Molding is today a full-service custom molder, metal fabricator, and contract manufacturer with annual sales over USD $270-million. The company has plants in seven locations in the U.S., operates injection molding machines from 28 to 4,000 tons, and employs 1,800 people. Mack provides design, engineering, prototyping, and complete manufacturing services. In 2007, Mack Molding was named Plastics Processor of the Year by the industry publication Plastics News.

In November 2007, Mack started up the new medical molding cell at Arlington, VT, as the latest step in carrying out a strategic decision made in 2000 to expand the company’s medical market share, according to Carl Bickford, headquarters plant manager. The fully enclosed cell uses positive differential pressure and fine-particle filters to provide a protective barrier for molding medical products. It has its own operating staff and technical resources, and operates on a 24-hour basis.

The resins regularly processed in the medical molding cell are polycarbonate, polyarylamide, polyphenylenesulfone, ABS, glass-filled nylon, polypropylene, and thermoplastic elastomers; they include both optically clear and opaque formulations. Because some of these materials are particularly challenging to dry properly, the drying speed and efficiency of the LPD system and the small size of its drying batches are particularly advantageous, according to Revane. “There is no worrying about cumulative drying time and polymer degradation,” he said.

Critical Advantages of Vacuum Dryers versus Desiccant Systems

Besides drying speed and small batch size, another benefit cited by Maguire for the LPD dryer is a substantial reduction in energy consumption, by as much as 80% in comparison with older desiccant dryers now in use. “Energy savings was not the deciding factor when we purchased the dryers for the medical molding cell,” said Bickford, “but it will be a consideration as we research the possibility of using larger LPD dryers for other production lines.”

While desiccant dryers flow hot, dry air over the pellets to slowly draw the moisture out and then use desiccant to adsorb the moisture, the 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. Need for desiccant is eliminated—and with it the cost of regenerating desiccant, which adds to the energy cost of conventional dryers.


MACK MOLDING CO. is headquartered at 608 Warm Brook Road, Arlington, VT 05250 U.S.A. Tel: 1-802-375-2511. Fax: 1-802-375-9419. Visit www.mack.com.

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, 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 three sales and service subsidiaries that stock, sell, and service auxiliary equipment systems from Maguire and its affiliate, Novatec, Inc.: Maguire Canada, headquartered in Vaughan, Ontario; Maguire Europe, supporting customers throughout Europe and operating a distribution center in Tamworth, Staffordshire, UK; and Singapore-based Maguire Asia, serving customers throughout South Asia and the Pacific Rim. Visit the Maguire Products web site: www.maguire.com