Steel has been an important part of human progress for thousands of years, but throughout most of that time, this strong and versatile metal had a fundamental weakness: its tendency to corrode. It was only in the last century that metallurgists were able to develop a form of stainless steel that could withstand the natural corrosion process characteristic of most carbon steels. This discovery would open the doors to a new wave of developments in the world of industry, including the field of medicine.
Steel is an alloy that primarily combines the elements iron and carbon. Civilizations have been using steel for nearly 4,000 years in weapons, tools and machinery. Prized for its strength and ease of manufacture, it has been a driver of industry in the modern world. However, since it is an iron-based metal, it is prone to rust in the same way that iron is. This made carbon-based steel impractical for many applications, including medical ones.
When a new steel alloy was developed in the early twentieth century, dubbed stainless steel for its ability to withstand corrosion, it opened a whole new world of possibilities for medical devices. A metal that was strong, easy to sterilize and no longer subject to rusting was perfect in a medical setting.
What are the advantages of stainless steel?
When it comes to surgical instruments, there are only a few metals commonly used. The list includes stainless steel, titanium, tantalum, platinum and palladium. Compared to stainless steel, these other materials are rare precious metals, and significantly more expensive. That makes stainless steel the most cost effective alternative for medical devices.
There are certain criteria that metals must meet in order to be considered an option for medical devices. First, the metal must be malleable enough that it can be shaped into the correct form, but not so malleable that it won’t remain durable over its lifetime.
The metal also must allow for a smooth surface, usually achieved through passivation or electropolishing. This means the instrument can be easily cleaned, which is of paramount importance in a medical setting. It’s not enough that the surface looks clean, but it must also not harbor any bacteria.
There is one important note that any manufacturer of medical devices must be aware of. In some cases, there is evidence that a small percentage of patients may have something like an allergic reaction to a metal’s chemistry such as stainless steel. The condition looks like an immune or inflammatory reaction that can be traced to where contact was made with the metal or it can become more widespread. The symptoms can include fatigue, rash, joint pain and/or muscle pain. That’s why it’s important to have alternative devices made of various metals just in case a patient is unable to be treated with stainless steel instruments.
What types of medical devices rely on stainless steel?
The first and most common category of devices that use stainless steel are surgical instruments. These are the cutting, probing and clamping tools a doctor would use during surgery, where sanitation is of the utmost importance. You need tools that can be thoroughly sanitized and won’t corrode despite exposure to potentially corrosive liquids.
Another type of device that might be made of stainless steel is an implant device intended to be temporarily or permanently inserted into the body. This can range from a pin or screw used to stabilize a fractured bone to an artificial heart valve. In either case, the device must be durable and completely resistant to corrosion even in a saline environment like the human body.
The manufacture of medical devices is necessarily a very precise endeavor. Lives are very literally on the line. Selecting the wrong material could have a disastrous effect and errors may have a punitive legal response. That’s why the use of only the most reliable and durable materials is so important.
In addition to those already mentioned, the list of medical devices that rely on stainless steel includes precision tubing, mandrels, chemical and hazardous waste receptacles, wires, needles, catheters, prostheses, curettes, cutting tools and metal plates. In addition, ancillary objects that also must be sterilized will also be made of stainless steel, such as trays, counter tops, bowls, sinks and more.
What alloys are frequently used in medical devices?
As should be abundantly clear by now, selecting the right material for a medical device is of the utmost concern. This includes which alloys should be used. The use case scenario of any device will tell you a lot about which possible alloys are suitable.
For many devices, especially those that won’t come into contact with the body, alloy 304, the workhorse of stainless steel alloys, is an excellent option. The advantages of 304 include its versatility, corrosion resistance, recyclability, durability, ease of cleaning, antibacterial properties, heat resistance and the fact that it is non-magnetic.
However, for surgical devices that will be used inside the human body, a higher level of protection is necessary. A high-performance stainless steel such as 316 offers even greater corrosion resistance thanks to its molybdenum content.
In special cases with more demanding requirements there are newer, more expensive alloys that can be turned to. Certain implant quality stainless grades are produced with a VIM/VAR process (Vacuum Induction Melting/Vacuum Arc Remelting) to produce the cleanest possible materials free of impurities.
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No matter what your application, there’s a stainless steel that’s right for you. At Clinton Aluminum, we’re committed to working with our clients through every step of the procurement process. The experience and commitment of our staff allow them to answer tough, complicated questions and make trustworthy recommendations.
No matter what industry you’re working in, performance matters, and we understand that. We will do our best to ensure your success. Contact one of our friendly and knowledgeable customer representatives today to learn more.
