Investigation of Wire EDM Cutting of Medical Thin Wall Delivery Catheters

Access to files

Full-text and supplementary files are not available from Manchester eScholar. Use our list of Related resources to find this item elsewhere. Alternatively, request a copy from the Library's Document supply service.

Abstract

This paper presents a unique investigation into the machining of thin walled stainless steel tubes using WEDM (wire electro-discharge machining). Thin walled stainless steel tubes can be used as a medical device in the form of a catheter. They can be used to aid the delivery of stents within the body, they are sometimes commercially referred to as hypotubes. The tubes tend to have a helical cut along the central axis, which provides the level of flexibility required to move around the body, however it still retains its structural strength.Laser processing is predominantly used to cut the helical shape in thin walled metal catheters, however industry sources indicate that a degree of post processing, involving chemical etching, is required to remove machining debris and dross. Therefore WEDM was investigated as a possible alternative as the process does not produce dross and a surface finish comparable to laser processing can be achieved.This paper reports the process optimisation work that was carried out to cut thin walled tubes (6.3mm outside diameter with an 0.55mm wall thickness) using WEDM. The effect of parameters such as machining voltage, pulse-on and pulse-off time are presented. The processed tubes were analysed using a confocal microscope and surface finish values of Sa 0.69μm were recorded. The effect on processing speed with the use of coated EDM wires on the manufacturing process is also presented.

Keyword(s)

WEDM thin wall tubes catheter stainless steel surface roughness

Bibliographic metadata

Institutional metadata

Record metadata