Medical-grade investment castings

The healthcare industry is constantly evolving, and recent years have seen an increased need for innovations in medical technology and portable, durable devices. At the same time, there is growing demand for medical components that not only deliver high performance but are also compatible with the human body during sustained use.

For many years, stainless steel was considered the only material suitable for manufacturing medical equipment. However, aluminium and cobalt-chromium alloys have recently found a place in the medical market.

Signicast investment castings use each of these alloys, together with precision capabilities and tight tolerances, to deliver the best performance in the industry.  

Stainless steel alloys for medical-grade equipment

Although material innovations for the medical industry are constantly changing, stainless steel remains a leading choice for most medical equipment manufacturers because of its resistance to low and high temperatures, high strength and biocompatible properties. Investment casting enables the complex geometries required to be engineered into the casting, improving part performance and reliability. Signicast's stainless steel alloys include different combinations of nickel, chromium and carbon. Depending on the application, manufacturers can choose between the 300 or the 400 series stainless steels.  

• The 400-series comprises 25% nickel, 1% carbon and 11-27% chromium.

• The 300-series contains 6-25% nickel and 16-30% chromium.

If high strength and cost reduction are priorities, the 400-series may be the right choice. However, for applications requiring high strength, high corrosion resistance and property retention at high temperatures, the 300-series group may be more effective.

Consulting a Signicast metallurgist is recommended to determine the most suitable material for specific requirements. There may be an available option that has not yet been considered.

Aluminium alloys for Class 1 & 2 devices and housings

While stainless steels meet the biocompatibility and strength requirements for Class 1 and 2 medical devices, their weight can limit usability. Aluminium alloys often offer lower total costs while maintaining a significantly higher strength-to-weight ratio than stainless steels. In addition, aluminium naturally forms aluminium oxide when exposed to oxidising agents, creating a protective layer that prevents further oxidation and component weakness. This is where lightweight aluminium has found its place in the market, producing medical components for applications such as handheld surgical devices and portable medical equipment that must be durable, lightweight and easy to use while also meeting stringent FDA regulations.

Cobalt alloys (ASTM-75) for implantable devices

Signicast has used cobalt alloys as an alternative to stainless steel, particularly for implantable devices. Cobalt-chromium, which is ferromagnetic, is very strong even at very high temperatures and offers high corrosion and wear resistance compared with other metals. It is also entirely biocompatible, making it suitable for implantable devices.

Medical component manufacturer

Medical devices, whether Class 1 or 2, include components that should meet and/or exceed the necessary efficiency and safety requirements set by governing bodies, as well as the physical and mechanical properties required by the manufacturer. This requires additional care when selecting the material for such devices and the right manufacturing partner for a successful programme launch.