Suppliers of extruded tubing to major medical device companies have improved their offerings with better primary machinery, auxiliaries and resins. Among new tubing: the PEEKshrink brand from Zeus Inc.
Machines are smaller and some suppliers are designing proprietary tubing and compounds, according to exhibitors interviewed at the Medical Design & Manufacturing West trade show, held Jan. 31-Feb. 2 in Anaheim.
Physicians who use medical tubing for minimally invasive surgeries are gaining the benefits of technological advances in extrusion machinery and secondary operations, said Jim Zivic, marketing manager with Teleflex Medical OEM of Bannockburn, Ill.
``Trends are toward smaller-diameter, center-wall, closer-tolerance tubing,'' said Zivic, who works out of Mansfield, Mass.
Primary extrusion equipment makers can offer lower-cost, integrated-control systems, according to Sean Lynn, associate director of extrusion research and development at the Teleflex facility near Limerick, Ireland. Such systems reduce the cost of integrating lines and constitute ``a big improvement,'' Lynn said.
Also, better ways to measure outside dimension and wall thickness ease the reporting task for quality control inspectors.
``Better machine controls are being used with the drives to the extruder,'' said Tom Bauer, president of Medical Extrusion Technologies Inc. of Murrieta, Calif. ``Downstream, better sizing control is being offered,'' he added. In particular, Bauer said he has seen advances in ultrasonic wall- thickness gauging.
Jim Dandeneau, president of Putnam Plastics Co. LLC, said ``extruders have gotten smaller over the years.'' For adjustments, computer-controlled lines with feedback controls link the puller to the extruder to the closed-loop system, Dandeneau said.
Dayville, Conn-based Putnam often coextrudes materials, and there is a lot more going on in that area, Dandeneau said, with ``multiple extruders connected through a common head'' to make certain-sized items.
Putnam makes complicated shapes under tighter tolerances and quality control, and, in some cases, to inner and outer dimensions unheard of years ago.
``The level has come up as far as the demand on our requirements and our quality,'' said Dandeneau, who founded Putnam in 1984 and sold it in November 2004 to Memry Corp. for $26 million.
In resins, polyurethanes with a polycarbonate component are among the better-accepted materials for medical tubes going into the body, Dandeneau said. Grades of aliphatic PC-based PU have proved to be better for long-term applications, he said, and are among ``the more popular resins, as opposed to a straight aliphatic or straight aromatic urethanes.''
Different materials - perhaps softer ethylene vinyl acetate-type compounds - and different wall constructions may yield results in the ongoing pursuit of a material to substitute for PVC, Bauer said.
Also, PEEKshrink-brand polyaryletherketone tubing is now available.
At the show, Orangeburg, S.C.-based Zeus formally launched the brand as an alternative to fluoropolymer tubing for critical medical, electrical and automotive applications.
The rigid high-temperature material is suitable for laparoscopic surgical devices and, in some cases, catheter systems for vascular or digestive system procedures.
A processor can apply PEEKshrink over metal or use the resin in metal replacement, perhaps in lightweight aerospace applications.
Tubing extruder Zeus supplies PEEKshrink in amber and tan versions.
Victrex plc manufactures PEEK in Thornton, England.
``Resins and machines are becoming highly specialized to address different applications and the needs of surgeon or the doctor in the hospital,'' said Timothy Steele, managing director of MicroSpec Corp. of Peterborough, N.H.
MicroSpec designs screws and processes, and creates solutions in its machine shop.
While some tubing extruders make compounds in-house, ``we happen not to, but [compounding] is becoming very specialized, and it is evolving,'' Steele said.
Technical applications include diagnostics for heart surgery. ``You need a very specialized catheter to get into the body,'' Steele said.
``It has got to be braided. You need torque ability to steer it through the body. The same is true of central line catheters'' now available for pediatric and neonatal applications.
``They have not had catheters for those people,'' Steele said. ``They do today.''
He said materials address issues of biocompatibility, comfort and inside-body functionality, and find use in laparoscopic and endoscopic procedures, which are usually minimally invasive.