Medical Instruments, Part 1 – Surface Finishing Requirements for Medical Instruments

Rosler Metal Finishing understands that medical instruments are subject to stringent quality standards. Whether during an office visit or a complicated surgery, material defects or malfunctions may create dangerous and even fatal consequences for patients and healthcare workers alike. Providing precise and durable surface finishes  for work pieces used in the medical industry is one of our passions.

In a series of blog posts, we’ll discuss the various technologies used for finishing the surface of medical instruments and how mass finishing and shot blasting play a key role, not only as intermediate steps but also for placing the final, finishing touch on these work pieces.

We begin with a basic question: What are the surface finishing requirements associated with medical instruments?

Materials Matter

Medical instruments are exposed to frequent use and subject to highly corrosive atmospheres caused by frequent sterilization in a steam pressure chamber, exposure to chlorine wipes, and ultrasonic cleaning. They must never fail. To minimize wear and prevent corrosion most medical instruments, especially surgical tools, are made from tough, slow wearing, corrosion-resistant, high-performance metal alloys including austenitic stainless steel, titanium, or cobalt chrome.

Cannula tips are commonly finished using mass finishing applications.

Some surgical instruments may even have tungsten carbide tips and edges for better resistance against pitting or scratching. Lower-grade metals including aluminum and plastic may be utilized for other medical components such as orthodontics, but never for invasive instruments.

Instruments are sometimes plated for better thermal conductivity (taking away heat from the body), electrical conductivity (for electrical equipment), higher strength, or absorbing light from lasers.

Performance and Standards

Besides the right material selection, surface treatment is an essential component of the overall manufacturing process of medical instruments.

Surface finishing in the medical field must ensure:

  • Biocompatibility – Most medical instruments need a very smooth surface to limit the risk of bacterial contamination. This is especially critical for invasive instruments.
  • Excellent Functionality and Long Service Life – With lives at stake, medical instruments must be able to reliably serve their purpose, 24/7, for an extended period of time, without ever impairing functionality.
  • Cosmetic Appearance – Many instruments must have a satin, non-glare finish without jeopardizing their biocompatibility. A non-glare finish prevents distraction during surgical procedures.
Hip stem featuring a non-glare finish.
  • Excellent Corrosion Resistance – Medical instruments must not get stained or corrode. They must be able to withstand frequent autoclave sterilization and exposure to harsh chemicals like chlorine wipes, ultrasonic cleaning, etc.

Stages of Finishing

Surface finishing for medical instruments is not a one-and-done process. During the manufacturing process, medical instruments can undergo multiple finishing operations.

After the initial shaping process by forging, casting, machining, 3D printing, welding, heat treatment, etc. The surface of the raw components may have to be treated for deburring/edge radiusing, general surface cleaning, or initial surface smoothing. The latter is especially critical for 3D printed components.

An example of a production chain using both mass finishing and shot blasting.

Along the production chain, intermediate finishing steps in the form of surface smoothing and polishing may be required as preparation for plating or electro-polishing. The final surface finishing stages for medical instruments may include passivation, high-gloss polishing, or placing a matte, non-glare finish on the surface of components and frequently incorporate plating and electro-polishing.

The Rosler Way

Whatever your medical instrument finishing needs are, you can count on Rosler Metal Finishing to help you find a better way and the best results. Contact us today to discuss your unique challenges.       

The complete Medical Instrument Series includes:

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