Exploring five of the most popular alloys used in the medical sector

Exploring five of the most popular alloys used in the medical sector

Supplying into the medical sector is not for the faint-hearted. While most industries have their own unique pressures, manufacturing wire that goes into products destined for the human body could mean the difference between life and death – in short, there is no room for error or failure.

And that’s just a small part of an arena that is worth 12.9% to UK GDP and encompasses an entire ecosystem that filters through to surgical knives and syringes and critical equipment used in medical settings throughout healthcare.

Choosing the right material to go into specific applications is crucial to the process, and with hundreds of alloys available to choose from, many design engineers find themselves scurrying around for technical help and assistance. The wrong choice of wire in the prototype stage can be extremely costly and even more costly if it goes into full production, then subsequently doesn’t deliver the level of performance expected of it.

With this in mind, Alloy Wire International (AWI) takes you through five of the most common alloys AWI supplies for use in the medical world.

Stainless Steel 316LVM

One of our most popular alloys is Stainless Steel 316LVM, which we supply to hundreds of customers all over the world. Regarded as ‘medical grade’, this material is vacuum melted to achieve the extremely high levels of purity and ‘cleanliness’ required for surgical implants that can be used to improve people’s daily lives.

Stainless Steel 316LVM, which can be supplied to specifications such as ASTM F1350, ASTM F138 and ISO 5831, offers excellent resistance in physiological environments and to general, intergranular corrosion and pitting and crevice corrosion. The material can be readily processed to achieve the required mechanical properties and, in addition to implants, can be found in syringes and numerous pieces of equipment found in operating theatres.

Phynox

A Cobalt-Chromium-Nickel alloy, Phynox is one of the most popular materials with AWI customers. It provides engineers with a combination of high strength, ductility and excellent fatigue life, making it a versatile alloy suitable for several challenging environments.

Phynox also has the added benefit of being an age hardenable alloy, helping it deliver additional strength and corrosion resistance in numerous environments, while also being nonmagnetic—the latter being a very important feature when considering the use of implants in human bodies.

Also known as Elgiloy, Coinchrome, FWM 1058 and Alloy 3J21, it can operate in sub-zero temperatures (below -200°C), which makes it ideal for use in cryogenic applications within the medical sector.

A difficult alloy to process, it can be used in human implants, medical devices, surgical equipment and even dental products.

Phynox was involved in one of my more challenging phone calls, when a customer made contact to ask it if was definitely nonmagnetic due to a patient needing an MRI scan, but having a Phynox wire mesh at the back of the patient’s eye socket. While we were 100% certain it wouldn’t be impacted by the procedure, we decided to send several samples of the alloy used in the mesh just so tests could be completed.

Specifications for Phynox within the medical sector are ASTM F1058 and ISO 5832.

MP35N

MP35N demonstrates comparable mechanical properties to Phynox and is often used in similar application areas. AWI supplies this age hardenable Nickel-Cobalt-based alloy in both coil and bars, the latter available for customers to machine their products directly out of, with end applications ranging from various dental products to orthopaedic implants.

MP35N, which can be ordered to ASTM F562 as well as to ISO 5832, provides excellent resistance to several different types of corrosion, and has good biocompatibility, both of which make it suitable for use in close contact with human tissue.

Nickel 200

This material is very different to the alloys mentioned earlier as it the only one that is a commercially pure nickel. Difficult to manufacture, Nickel 200 is not typically viewed as a medical grade wire and that can sometimes mean it is discounted when products are being developed. The reality is somewhat different. Due to its excellent corrosion resistance in alkalis and the fact it has high electrical and thermal conductivity, this material has proven a very good fit for sensors, smoke detectors and other ancillary equipment found in medical environments.

Additionally, good ductility is another important trait of Nickel 200, so you can shape and reshape components out of it quickly and easily.

There are several other alloys within AWI’s range, which are also used in the wide-reaching world of medical applications.

Haynes 25

Traditionally, AWI has supplied limited quantities of Haynes 25 to the medical sector, but that could well be about to change with a recent increase in orders being taken for the Cobalt-Nickel-Chromium-Tungsten alloy that combines high strength with corrosion resistance.

Specified to ASTM F90 and ISO 5832, it is known as one of the strongest of the formable Cobalt alloys and boasts excellent biocompatibility, making it a potential choice for surgical implants, such as stents or meshes for securing bone fragments.

A quick word of warning though, it is extremely difficult to process, and a lot of wire manufacturers will steer you away from it.

Meeting the needs of the medical sector

We have supplied the medical sector for more than 20 years and are seeing renewed interest from spring and specialist manufacturers who supply equipment to healthcare settings all over the world.

At AWI, we have responded to the need for exacting standards by securing the ISO:13845 medical quality accreditation and investing heavily in updating testing facilities that are equipped with two tensile testers, a Micro-Vickers Hardness tester and four lab furnaces to deal with heat treatment samples.

Macro and micro imaging technology has also been installed, in addition to a custom-built metallographic lab to help with the preparation of materials.

This project means a lot of the subcontract testing can now be done in-house, shortening lead times for our global customer base, and giving us the opportunity to test new processes and materials quickly.

Technical expertise is another area we are strong in, and this has been reinforced by the appointment of Lee Knight as Technical Executive to our four-strong quality team.

Our medical customers expect the very best when it comes to world-class performance, and it all starts with choosing the right material. Get that right and everything else follows.

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