Dunn Industries—which specializes in medical tubing—extruded Medalist MD-500 Series compounds at its Manchester, NH facility. “The Medalist elastomers exhibited a wide processing window and maintained close tolerances,” said company president Duane Dunn. “Tubing was easily cut to length in-line with extrusion.”
Pelham Plastics (Pelham, NH), which specializes in custom injection molding and assembly of medical devices, readily carried out a variety of downstream assembly techniques with tubing produced from Medalist MD-500 Series elastomers, according to John J. Mackey, president. “The fabrication performance of tubing produced from Medalist compounds was outstanding,” Mackey said. “The tubing was easy to work with even in our most innovative techniques, such as hole-punching and tipping, and we were able to carry out every fabrication technique with great precision.”
Pelham Plastics reported on these techniques:
● Hole punching posed no problems, even allowing for tube rotation producing a serpentine pattern; though this process is typically difficult for elastic materials because of stretching or tearing.
● Tipping—the process of forming a tapered closure at the end of a tube—was carried out without need for pretreatment or release agents, which would require additional regulatory approvals. “The tipping performance of tubing produced from Medalist compounds was awesome,” said Pelham Plastics sales manager Ray Pellerin. “Cycles were fast, there was no sticking, tapers were consistent, and the aesthetic quality of the finished product was excellent.”
● Printing was carried out successfully using standard automated corona surface treatment and traditional pad printing with conventional inks. Teknor Apex also has suggested inks that could be used without the need for pre-treatment.
● Insert molding, in which luers were applied to the ends of tubing, involved short cycle times, no tube distortion, and excellent bonding of the tubing to pre-colored luers made either of polypropylene or Medalist elastomers.
Compared with PVC, Medalist MD-500 Series tubing compounds exhibit comparable crystal clarity and mechanical properties; provide similar clamp resilience and resistance to kinking and necking; have a similar “feel”; and are substantially more flexible and significantly less dense than PVC. At the same time they undergo minimal color shift upon heat aging after exposure to gamma irradiation, the most severe type of sterilization. A typical compound in the series, Medalist MD-575, actually exhibits 70% less heat-aged color shift than a gamma-stabilized PVC compound of comparable hardness.
