Produce an utra smooth "glass like" surface finish The low shrink temperature and high melt temperature of polyester heat shrink tubing enables it to be used very effectively to form smooth tapered tips on the ends of catheters and other medical devices. In the initial operation, a section of heat shrink tubing is slid onto the end of a catheter tube, leaving a tail off the end. A coated metal rod or PTFE beading is inserted in the catheter to maintain the tip ID. Heat is then applied to shrink the tubing onto the substrate, causing the substrate to melt and flow. Pulling on the heat shrink tube draws the catheter tube to a very thin, smooth tip. Since the shrink tubing is clear, the operator can monitor the process. The shrink tubing is removed to complete the job, leaving an ultra smooth finish.
In catheter tip forming, clear polyester heat shrink tube is first attached to the end of a catheter tube, then more heat is applied (with hot air torch extending from background), while a hemostat (at right) is used to pull and draw the shrink tube, forming a smooth tapered tip. A mandrel is used to prevent the tip I.D. from collapsing during the process.