Modern Grinding has the capabilities to manufacture both stainless steel coils and nitinol coils, and some of our clients have asked us what the difference between the two is. The difference is mainly the amount of nickel and titanium present (sorry that was a very dry metallurgy joke – nitinol is mainly a combination of NIckel and TItanium which is how they derived the name for the metal). Obviously that is the difference, but was is the difference in performance, cost and in production.
In performance, nitinol wire has the property of not kinking. It takes a lot of force relatively to make nitinol kink. Nitinol is more flexible. These two properties are very helpful in creating internal medical devices. Also nitinol has a memory property, the ability to revert back to an initial position when there is a change in temperature of the material. For instance within orthodontic devices, nitinol springs can try to either push teeth away from each other, in a open coil design or pull teeth closer together in a closed coil design. Nitinol can self-expand (compression) or self-contract (induction) depending on the needs of nitinol springs within your medical device.
Stainless steel coils don’t have the shape memory property that nitinol contains. Stainless steel is best used if you need more rigidity in your coils or if you need your coils to more firm. Modern Grinding is able to achieve stainless steel and nitinol coils out of round or flat wire to very small tolerances. Stainless steel coils can be easier to weld with a stainless steel core wire. It is possible to weld nitinol but depending on the amount of material that you are welding, stainless steel provide a stronger bond. Don’t hesitate to contact Modern Grinding with your custom coil project today!
The cost of manufacturing nitinol springs and stainless steel springs varies as well. Nitinol typically costs more since it is not as prevalent of a metal within the materials supply chain. The material pricing difference is not as prevalent if the manufacturer has a long lead time to get material from an original raw material supplier. Since coils tend to not be as heavy in material, the big pricing difference comes in secondary processes needed with coils. Depending on the number of processes that you need to do to the nitinol, your costs can add up, since nitinol is more abrasive material than stainless steel and since most finishing companies aren’t as accustomed to working with nitinol.
Hopefully this post provide a little insight into the differences between stainless steel coils and nitinol coils. We have an internal engineering department with experience designing coils with a variety of materials and designs. If you have specific questions don’t hesitate to give us a call!