Medical tubing concentricity control improves

Demands for tighter tolerance and higher quality are growing for many medical applications, including tubing.

American Kuhne (Ashaway, RI) this week released test data it says confirms quick automatic control of tubing concentricity. The technology was demonstrated with a Zumbach OD and wall system at the MD&M East show in Philadelphia last June.

Die pin heater control technology.

American Kuhne is using die centering technology originally developed and patented by partner Graham Engineering for parisan sidewall adjustment.

The technology includes an AK Fixed Center die head that is said to eliminate manual die centering. Instead, the die pin center location relative to the die bushing is adjusted by touchscreen control of four die pin heaters, which are located in the rear mandrel of the die head. Heating is done in an uneven pattern to "flex" the die pin to control its position.

The technology incorporates closed-loop control of tubing wall thickness concentricity by integrating the control system with an online OD and wall thickness gauge controller.

To confirm results of the system, a testing company called LaserLinc (Fairborn, OH) incorporated its Triton triple-axis micrometer, UltraGauge+ ultrasonic wall thickness measurement system and Total Vu software with OPC (Object Linking and Embedding for Process Control).  The wall thickness data collected by Total Vu went to American Kuhne's PLC where the closed-loop control kicked in.

A press release from American Kuhne said that  the concentricity was intentionally taken out of specification several times and each time the control system recovered to 90% concentricity within a minute and after just five minutes the concentricity was stable at 98%.

American Kuhne is a supplier of standard and customized single screw extruders, feed screws, and complete extrusion systems for medical tubing, pipe, and profile. LaserLinc is a manufacturer of non-contact laser and ultrasonic systems for OD, ID, wall thickness, eccentricity, and concentricity across many industries including wire, cable, medical and other tubing, hose, pipe and fiber.


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