How are dimensional tolerances controlled in the extrusion process?

Tolerance control in silicone tube extrusion requires simultaneous management of tooling design, process parameters, and in-process monitoring. The die design itself is foundational: multi-land flow distributors and choke rings compensate for uneven melt velocity distribution across the die gap, which is the primary source of wall thickness variation. Die head temperature stability is equally critical, as melt viscosity — and therefore wall distribution — responds directly to temperature fluctuations. On the process side, extrusion speed, haul-off speed, and screw RPM must be matched precisely; a drift in any one of these produces either eccentricity or longitudinal dimensional variation. Vertical extrusion has an inherent advantage over horizontal lines for tight-tolerance thin-wall tubing: gravity acts parallel to the extrusion axis, which promotes uniform melt distribution and reduces the tendency for the tube to sag or deform before it sets. Ruixiang uses vertical extrusion throughout its medical tubing lines, holding inner and outer diameter tolerances within ±0.02 mm, with a minimum processable inner diameter of 0.14 mm and wall thickness of 0.1 mm. Production runs under ISO 13485:2016 with full traceability.

For product specifications, technical data sheets, or sample requests, contact the Ruixiang team: olivia@dgruixiang.com  |  www.medicalsiliconetube.com