Flash minimization in catheter tip forming through core design and pin–tube arrangement

This study proposes forming strategies and core designs to minimize flash formation in ETFE (ethylene–tetrafluoroethylene) catheter tip thermoforming using a structurally simple upper heating plate system. Two forming methods are proposed: (i) an outlet-shearing method in which the tube extends beyond the pin and excess softened material is discharged through the core outlet and removed by shearing, and (ii) a pin-sealing method in which the pin is advanced to the core end to block the outlet and prevent material leakage. Three core designs with different outlet diameters, rounded features, and pin–tube arrangements were evaluated under identical forming conditions: a forming temperature of .370°C, forming time of 5 s, cooling time of 5 s, and insertion height of 58.0 mm. Among the three tested core configurations, core (c), which incorporated the pin-sealing strategy, showed the lowest mean flash length of 73.3 μm and a defect rate of only 2.0%. Its mean flash length was approximately 76.6% lower than that of the highest-flash core (a) (313.3 μm). These results indicate that high-quality catheter tips can be consistently manufactured using structurally simple heating equipment through appropriate core design and pin–tube arrangement, with the potential to improve product reliability and reduce equipment complexity and manufacturing cost.