The Most Important Metals Used for Medical Devices

Developing healthcare devices or other medical products requires a careful selection of manufacturing materials. Metal materials are often the best choices for applications requiring high durability and strength. Devices that are subject to increased mechanical stress should be made with metals.

Asides from their mechanical properties, medical metals must meet certain criteria to qualify them for medical applications. Some of these criteria include corrosion resistance, lack of toxicity, non-magnetic, and more.

Metal manufacturing is essential in the medical industry, and there are many variables involved in selecting metals. Thus, the FDA and other agencies only certify the final product and not raw materials. However, the first step towards manufacturing quality medical devices is selecting biocompatible materials.

This article will examine the most important metals for medical applications.

Examples of Metal Machined Medical Devices

Various machining processes help to make essential precision-machined medical parts such as:

What Are the Most Important Metals for Medical Industry Applications?

Several metals and alloys are available for real-world applications in the medical industry. Here are some of the most common metals and their uses in the healthcare sector.

1.     Stainless Steels

Stainless steel alloys are among the most common metals for several products. It is a corrosion-resistant, durable, and non-toxic material, making it ideal for different medical applications. Stainless steels also allow fine surface finishes to ensure easy cleaning of materials.

There are various stainless steel types used in the medical industry. The 300 series are usually the first choice when metal parts are to be included in designing a medical device.

This is because of their non-corrosive nature and ease of fabrication. They also offer superior physical and mechanical properties.

The common ones include the following:

Generally, stainless steel is able to withstand very high temperatures, going up to 400°C. This means that they can be easily sterilized in autoclaves and ovens.

They are high-performance metals with their popular use is in orthopedic applications such as joints replacement or for stabilizing bones with plates and screws.

Stainless steel alloys are also important due to their durability and ease of cleaning and sterilization. These properties make them useful in surgical devices like forceps, tweezers, arterial-plaque removers, and hemostats.

2.     Cobalt-Chrome Alloys

Cobalt-chrome is another common metal used in the healthcare sector. It has high strength, wear-resistance and can endure high temperatures. For this reason, it is mainly used for dental implants and replacement joints.

Cobalt-chrome metal alloy used in orthopedic implants often has cobalt, chromium, molybdenum, and other elements. It is a biocompatible metal, making it even more useful.

Moreover, electropolishing makes cobalt-chrome alloys have smoother surfaces, preventing contamination. Despite being quite hard, custom machining can help to create parts from cobalt chrome easily.

3.     Titanium and Its Alloys

Titanium is currently the preferred substitute to stainless steel for bone replacements and skeletal supports. It is a light material that has excellent biocompatibility. Despite its lightness, it is very strong and durable.

The biocompatibility of titanium alloys is due to their inert nature. This makes them useful for parts that remain inside patients after surgery and other high-reliability parts. Such parts include implantable devices, joints replacement, bone screws, etc.

Manufacturers employ titanium in areas where stainless steel does not meet therequirements for strength, hardness, and corrosion resistance. Ti-6AL-4V titanium alloys are widely used for implantable applications.

Grades 1 and 2 titanium are also versatile because they allow various manufacturing processes. These alloys are more heat resistant, able to withstand up to 430°C. When exposed to air, it can also form protective oxide film, making it highly corrosion resistant.

You can have a perfectly customized medical device from a patient’s scan with titanium. It is a metal of choice for orthopedic plates, pins, rods, and dental implants.

4.     Copper

Copper is a rather soft metal. Thus, designers rarely select it for use in medical implants because its softness may lead to toxicity in tissues. However, manufacturers still use some copper alloys in dental implants.

They also use it to make parts that help prevent infections during bone transplant operations. The outstanding antibacterial properties of copper make it very useful. These properties make it ideal for regularly touched surfaces like bed rails, door handles, and switches.

Another unique advantage of copper is that the FDA has approved over 400 copper alloys as biocidal for preventing viruses, including the Coronavirus.

5.     Aluminum

While it can be rarely used in products in direct contact with the patient’s body, aluminum is useful for many support equipment that should be strong and light. Examples of these equipment include medical instruments, wheelchairs, orthopedic supports, etc.

It also imparts corrosion resistance to the component. Raw aluminum can easily oxidize and tarnish. Therefore, surface finish of parts made with aluminum is important for durability.

6.     Magnesium

Magnesium is a biocompatible metal with an excellent strength-to-weight ratio. However, it is not a traditionally used material in a medical device. This is because magnesium can be very reactive when exposed to oxygen or other liquids.

Sometimes, there needs to be some surface treatment before using parts made from magnesium. However, magnesium tends to safely and naturally biodegrade. This property makes it commonly used in the manufacture of bone graft replacements and heart valves.

Using it in heart stents, for example, prevents the need for other surgical procedures to remove the stent. Pressure die casting and machining of magnesium are also possible for making large parts.

Considerations for Choosing a Metal for Medical Products

While these materials have their unique properties, finding the best one for your application is crucial. Here are some of the things to consider:

Mechanical Properties

Metals used for medical equipment should be typically malleable to enable easy and accurate shaping. However, they should not be too malleable to prevent them from breaking during use. They must also be fairly ductile – the lowest modulus is 100GPa.

Ability to Withstand High Temperatures

Medical tools and devices are often subjected to increased temperatures during sterilization. Sterilization in an autoclave often reaches up to 121°C for 30 minutes.

The sterilization done in hot air ovens may reach up to 160°C for one hour. Thus, the material you choose should only experience minimal dimensional change after sterilization.

Corrosion Resistance

Surgical instruments often get in contact with human body fluids, cleansers, and water. These fluids contain elements that can cause corrosion. Rusting can severely stain the materials, making them dangerous for use in patients.

Therefore, you want to choose a material with high resistance to corrosion. A typical example of such metals is stainless steel. However, anodizing and other surface finishes can make metals aluminum less corrosive.

Biocompatibility

The material you choose for your metal equipment must be biocompatible with the body’s tissues. Biocompatible materials are those that do not produce immunological or toxic biological responses when exposed to the body.

The different titanium and stainless steel grades are biocompatible and do not cause hypersensitivity issues.

Resistance to Wear and Tear

Medical instruments need to have the highest level of performance. Therefore, you should select a strong and durable material enough to withstand the operational environment in the medical industry.

It must be durable and reliable when subjected to heat, vibrations, corrosives, and others—titanium grade comes out on top here. However, stainless steel and other metals in this article are strong enough to withstand operational environments.

Which Medical Metal is Right for Your Application?

Titanium, stainless steel, and nickel-based alloys are typically more intricate than other materials infrequent use. However, they also have a considerably broader range of capabilities. These ‘special metals’ can be customized to specific design needs via various machining processes.

This will help them demonstrate certain physical and mechanical properties. Once you are familiar with the intricacies of the metals, you will notice the exceptional ones for your medical applications. They offer many unique benefits for medical applications.

These benefits include corrosion resistance, exceptional versatility, and other optimal properties. In the end, the right metal for your product will depend on the applications of such a product.

Conclusion

There are several metals available for use in various industries. However, the medical industry has unique requirements for its products. Some of the most important metals for medical products include stainless steel, titanium, copper, aluminum, cobalt-chrome, and magnesium. It is crucial to consider the properties of these metals and their alloys to choose the best grades for your product.

The professionals at AT Machining have extensive knowledge of the various metals. Hence, we ensure that all our projects support medical industry use. Our certification and expertise allow us to deliver the best on every project. Contact us today, and let’s get to work.