The Need for Metal Finishing in the Medical Device Industry

In the medical industry, devices are used both internally and externally, so biocompatibility is critical.


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Metal finishing meets the many challenges the medical device industry faces—strict sanitation, reliability, varying size—all while providing optimal performance.

In the medical industry, devices are used both internally and externally, so biocompatibility is critical. The process begins with raw bar stock or sheet stock being made into some kind of instrument that ends up being clean, defect-free and burr-free to meet stringent regulatory demands and undergo rigorous biocompatibility testing.

Many areas of medicine, including orthodontics, dental and even veterinary, face biocompatibility challenges, with orthopedic and cardiovascular implants being some of the most common. Orthopedic devices continue to evolve, and new implants for knees, hips, shoulders and elbows are rapidly being developed. Cardiovascular implants including defibrillators, pacemakers and artificial heart valves all have metal in them and need to stand up to blood in the human body.

 

Advantages of Electropolishing for Medical Devices

Certifications such as the ISO 13485 are designed to help manufacturers meet the medical device industry’s stringent demands. This requirement of higher quality finishes and standards is unique, but not surprising, considering the many specialized applications and concerns in the medical field, such as the spread of pathogens or “superbugs.” Although many may be disposable, devices must have smooth, corrosion-resistant surfaces that will not harbor bacteria.

Electropolishing is an ideal final finishing process for medical, and no comparable process can achieve the same high quality finish. Many manufacturers, for instance, specify passivation, which is sufficient for certain applications, because it can effectively clean and remove free-iron from the part’s surface. However, passivation does not produce the microfinishing and levels of corrosion resistance of electropolishing.

Some alloys, such as stainless steel, will naturally offer some corrosion resistance. However, any impurity on the surface (such as oil) will inhibit stainless steel from maintaining its natural state and corrosion-free surface.

Other commonly used mass finishing processes such as tumbling or burnishing can remove burrs and certain defects, but an additional process is still required to achieve the final micro finish. Pickling and other processes are unable to produce the required finish, and plating, for example, may ultimately result in peeling and flaking that may cause adverse reactions.

Color anodizing is also widely used by medical device manufacturers; with the FDA’s recent passing of the Unique Device Identifier enactment, it can help identify and match up surgical components. Laser marking can also be effective for identifying parts, but the uniqueness of electropolishing is that a single operation can achieve all of these benefits.

 

Critical Processing Requirements

Control and reliability in the process is key for any medical device manufacturer. Able Electropolishing’s process, for example, is tightly controlled. As an ISO13485- and ISO 9001-certified company, we ensure that we are processing in accordance to these standards. Additional internal validation processes for passivation, electropolishing and laser marking are also of high interest to the medical device industry. Processes that are tightly controlled can test for failure modes and worst-case scenarios. These internal validations allow for testing of groups of parts to be processed under different conditions. For example, processing parts with low, medium and high stock removal and different processing parameters. This ensures that the process is controllable and highly repeatable, ultimately resulting in a finish that is consistent from lot to lot and part to part.

An additional concern for medical device manufacturers, and insurance companies, is patient recovery. Shorter recovery is critical to the patient’s overall health and reduces healthcare costs, especially with implantable devices. The key to preventing problems such as implant rejection or infection is to use higher quality parts and strict sanitation policies. This will improve fit and function and yield better results for surgical procedures.

 

Continued Process Improvement to Support Industry Changes

Recent improvements in the medical industry require improved finishing processes. Today’s increased use of titanium, for example, is fueled by its lower rejection by the body, lightweight characteristics and improved tissue growth. Able Electropolishing has performed extensive R&D on rare alloys such as titanium, Nitinol, tantalum and other inert materials. Although these are superior alloys, they still require quality finishing.

Commitment from the metal finishing industry and individual metal finishers to improve the finishing process is key to supporting the medical device manufacturing industry.

Tom Glass is president at Able Electropolishing, an electropolishing specialist that offers electropolishing, passivation, titanium anodizing and laser marking services. For more information on Able, visit ableelectropolishing.com.

 

Originally published in the October 2015 issue.

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