Anaheim, Calif. — A Conair/Davis-Standard/Zumbach collaboration coextruded 1.4-millimeter-diameter catheter tubes in a demonstration of extrusion, sizing/cooling, gauging, cutting and quality control technologies.
“Temperatures are the key to the process,” Kevin Dipollino, Davis-Standard LLC product manager for pipe, profile and tubing systems, said at the UBM Advanced Manufacturing expo in Anaheim.
It took about six to eight months of development to perfect the process for manufacturing the thin tubes of medical-grade materials, according to Bob Bessemer, medical market sales manager for Conair Group's downstream extrusion products.
Chemours Co. of Wilmington, Del., supplied the Teflon-brand FEP 100 copolymer of tetrafluoroethylene and hexafluoropropylene. In the demonstration, the primary 0.75-inch Davis-Standard extruder delivers clear FEP for the main body of the tube. The primary extruder has a direct-drive water-cooled motor.
A second 0.75-inch extruder using a special Davis-Standard low-volume output screw delivers four equally spaced white FEP Teflon stripes that, for X-ray opacity, are filled with 8 percent BaS04 barium sulfate by weight of the solid.
Davis-Standard's program-logic-controller-based eVue system coordinates functions of the two extrusion lines, and Guill Tool & Engineering Co. Inc. of West Warwick, R.I., supplied a special low-residence-time cross-head coextrusion die that combines the two resin streams.
The four stripes of the barium-filled material are embedded at 90-degree intervals around the circumference of the tube.
After exiting the die, the tube enters a Conair MedVac-brand vacuum-sizing/cooling tank that creates pressure inside that tube, helps stabilize dimensions and prevents cooling water from drooling out of the tank's feed opening and affecting the surface finish of the tube.
An ultrasonic gauge inside the tank monitors the 0.4-mm wall thickness. Downstream, a Zumbach Electronics Corp. three-axis outer-dimensional laser gauge provides closed-loop control and displays the tube for concentricity adjustments.
Data from the gauges controls puller speed and vacuum to maintain critical dimensions. A vision system detects gels and surface imperfections and communicates with the quality mode to automatically separate good versus bad tubes in-line.
A Conair MedLine puller/cutter pulls the tubing down the line during sizing and cooling. A rotary-knife cutter slices the tube precisely to the specified length. Cut lengths are then carried on a Conair medical takeaway belt conveyer.
Once on the conveyor, cut pieces not meeting quality standards are removed from the production stream with a puff of compressed air.
The MedLine puller/cutter's scrap/quality-control mode accepts inputs from the wall-thickness gauge, the laser OD gauge and the cameras. The puller/cutter automatically sets a length offset so the cutter anticipates when a defective piece will reach it.
The cutter can be programmed either to cut tubing differently from good product or not cut at all, or it can change the way defective section is handled by the conveyor.
Also in Anaheim, auxiliary equipment provider Conair exhibited a MicroWheel MW1-0.2 dryer with a 0.2-cubic-foot hopper, a self-contained MedLine MiniLoader with its own vacuum motor to draw resin from machine-side storage, new thermolator temperature controls, a MedLine EP1A-03 portable air-cooled chiller and a MedLine floor-mounted TB-45 TrueBlend gravimetric blender.
Conair of Cranberry Township, Pa., is a business of privately owned IPEG Inc., also of Cranberry Township.
Extrusion and converting machinery maker Davis Standard is based in Pawcatuck, Conn.,
Zumbach Electronics of Mount Kisco, N.Y., is the U.S. division of Zumbach Electronic AG of Orpund, Switzerland.
