According to its application, you need to select fine wire based on criteria such as thickness, conductivity, metal malleability and strength. Very fine wires are found in a very wide range of industries and their roles are diverse. Depending on the application, the importance of close tolerances on both mechanicals and dimensions will vary, and it is important to be considered during material selection.

Fine wires for the medical device industry are usually found to be stainless steels. However the industry is moving towards more exotic grades with enhanced properties to achieve the desired end result. In these highly critical applications, both dimensional and mechanical close tolerances are vital in order to manufacture a product where it is essential that it is to work first time. These applications can be used in life or death scenarios such as stents, where failure of the product could be disastrous for the patient.

Below we discuss the importance of close tolerances in one particular application for medical fine wires, which is for producing medical coils from flat wires. Controlling the tensile range of the manufactured wire is essential as this can impact:

The shelf life of the product

By increasing/decreasing the tensile of the wire, this can cause the speed at which the internal diameter and pitch of the coil changes over time. Therefore it is important that we maintain a small range of tensile strength for this application.

The pitch and internal diameter of the coil can be controlled using tensile strength of the wire.

In this example it is also essential to control the width of the flat wire to achieve a consistent coil. Even relatively small variances in dimensions of the flat wire can cause large differences in the quality and consistency of the manufactured coil. Therefore close tolerances on both mechanical and dimensional criteria are essential to the successful manufacture of these products. 

We also see the importance of close tolerances in other industries too. Braiding, knitting and weaving are all processes that require material that is tailored to the machine they are being used on. Yield strength and tensile are both parameters that are vital for this process and are typically specified with a small range for wire manufacturers to work to. Close tolerances on the dimensions of the wire are also vital to produce a consistent and efficient product. It is fairly typical to see wire breaks in these processes and wire manufacturers work to reduce the chance of this happening by tailoring the specification to suit the customer’s process. Wire breaks can sometimes be a simple problem to solve and is not always down to the wire mechanicals. It is very important to have consistent wire spooling, which matches as close as possible the winding tension on the bobbin to the pay off from the braid/knitting/weaving machine. 

Avocet precision metals understand the importance of close tolerances in precision wire products for critical applications and can work with customers to improve efficiencies and product performance.