Balloon catheters are a key technology in medical devices, essential for minimally invasive procedures. This study quantitatively analyzes how the orientation characteristics of polymer tubes, influenced by extrusion conditions, affect the mechanical properties and compliance of the final balloon—where compliance refers to the change in diameter under external pressure. Nylon 12 tubes, with a target outer diameter of 1.2 mm and an inner diameter of 1.0 mm, were extruded under six different orientation conditions by varying the screw flow rate and puller speed. The tubes were processed under identical forming conditions, allowing for a consistent evaluation of their mechanical properties. As orientation increased, elongation decreased while yield strength increased, and these trends continued in the balloon, significantly influencing compliance. To quantitatively measure orientation, we introduced the dimensionless Deborah number. We established a curve-fitted experimental model that links extrusion conditions, polymer tube properties, and balloon compliance. This model allows for the prediction of balloon performance based on extrusion-stage parameters, providing a practical framework for process optimization. Overall, this study offers an effective quantitative indicator for forecasting balloon catheter performance based on extrusion conditions and supports the systematic design of medical balloon products.

As the market for minimally invasive procedures developed rapidly, there was an increase in the demand for high-precision, high-performance catheter fabrication technology. Sheath and dilator tubes are essential intervention devices for procedures, in which catheters are used and require precise dimensional accuracy, and uniform roundness and surface roughness. Polyethylene is used in sheath and dilator limitation for processability, which causes low melt flow index and side effects. Therefore, in the extrusion process using polyethylene, it is important to study the manufacturing of tubes with improved roundness and surface roughness. In this study, we proposed a calibrator for precise production with an aim to manufacture 5Fr micro-puncture tubes, and studied the changes in the roundness and surface roughness of tubes by changing the cooling water temperature and water disk thickness. As a result, it was found that the cooling water temperature and wafer disk thickness had an effect on the roundness and surface roughness, and the roundness had an effect on the formation of the wall thickness. Therefore, these experimental results were used as a study for the production of improved Sheath and Dilator tubes.

Catheter tip forming is processing the tip at the distal end so that catheter can move smoothly through the geometrically complex vascular structure. This thermoforming process has a problem in that the polymer tube adheres to the outer surface of the mold. To resolve this problem, previous researchers have coated the outer surface of the mold with PTFE (Polytetrafluoroethylene), which has a low coefficient of friction. However, due to repeated use, the coating is detached and the polymer tube adheres to the mandrels again, and the mold is frequently replaced. Thus, in this study, three types of metal were electroplated on the surface of the mold in to realize the performance of the PTFE coating. To select the optimal plating material, Cr, Zn, and Ni were selected as candidate groups. Surface energy, adhesion force, and abrasion depth & volume were measured for performance comparison. As a result, Ni, which has similar surface properties to PTFE, and the best durability, was selected as the optimal material. Based on these results, we present Ni-plated mold that can replace PTFE.

Recently, as the aged population grows around the world, many medical instruments, devices, and their fabrication processes are developing. Among the devices, a drug delivery stent is a good example for precision machining. Conventional drug delivery stent has problem of the remaining polymer because the drug is coated on the surface with it. If the drug is impregnated into the micro hole array on the stent surface, the polymer can be perfectly eliminated. Micro sized holes are generally fabricated by laser machining however, the fabricated holes do not have an enough aspect ratio to contain the drug or a good surface finish to deliver the stend to blood vessel tissue. To overcome these problems, we propose a vibration-assisted machining mechanism with PZT (Piezoelectric Transducers) for fabrication of micro sized holes better. The results indicated that the burr size can be significantly decreased with vibration assisted in nanosecond pulse laser drilling test.