Biocompatible surface treatments for medical-grade die castings

Traditionally, stainless steels were thought to be the only material that would meet FDA approval for manufacturing biocompatible medical devices. However, innovations in die casting surface treatments allow medical manufacturers to choose among a variety of specialised coatings and surface finishes to meet the rigorous testing and validation required by the FDA/EMEA. Today, you do not have to limit your material choice to one or two options. With Dynacast surface treatments, you can take advantage of the speed and cost savings of zinc Multi-Slide or our thin-wall aluminium casting while still remaining compliant with the FDA.

Anodised aluminium for medical castings

Aluminium is often selected for many applications because of its strength-to-weight ratio, relatively low manufacturing cost and ability to be coloured, while maintaining a high degree of thermal conductivity. Medical and healthcare manufacturers can take advantage of the benefits of aluminium for external medical applications by using surface finishes for optimum biocompatibility.

In the medical industry, the process of anodising aluminium is often an important first step that enables other necessary surface treatments and enhances the material's durability and corrosion resistance. Anodising is an environmentally safe electrochemical process that changes the surface of aluminium into porous aluminium oxide, creating an end product whose finish is more receptive to colouring or protective coatings, such as parylene. In healthcare, this means anodised aluminium medical equipment will last longer and can be manufactured to comply with biocompatibility regulations.

Parylene surface finish

Parylene has been used as a stable surface treatment for medical equipment for decades. This reliable protective coating is biocompatible and conforms to USP Class VI and ISO 10993 standards. It is transparent, pinhole-free and conforms precisely to the contours of any surface. Parylene coats extremely consistently and thinly (as thin as 0.0005"), providing coverage even in the most complex geometries and adding very little weight or volume.

These features make parylene an ideal coating for zinc and aluminium die-cast medical components. The die casting process offers many advantages over machined components, such as unmatched strength and precision, as well as cost savings. The addition of parylene allows medical manufacturers to take advantage of the benefits of die casting without sacrificing compliance or complexity.

E-coating and conversion coating (Chem film)

Conversion coating, or chem film, is an FDA/NSA-approved treatment process for aluminium medical components. Conversion coating produces a conductive protective coating without any dimensional change and enhances corrosion resistance while also improving adhesion for paint finishes. E-coating provides medical devices with a cosmetic finish and an extra layer of protection. Much like anodising, e-coating and conversion coating surface treatments extend the durability of medical equipment while also meeting FDA regulations. Like parylene, conversion coating is extremely thin (with a thickness of less than .000001"), so you do not have to sacrifice complex geometry.

Improving your surface finish with Dynacast

It is the healthcare provider's job to improve the patient's condition, and the medical manufacturer's job to improve the tools used to serve the patient effectively. Depending on your project requirements, there are several biocompatible surface treatments and finishes to choose from that allow you to take advantage of the die casting process and alloys.

While anodised aluminium, parylene and conversion coating are excellent options for metal medical components requiring greater biocompatibility, several other options are available for parts subject to less stringent regulations. At Dynacast, we have experience solving problems and engineering solutions for the medical industry, including streamlining FDA validation.