If you work in the medical device manufacturing industry, you have to abide by strict standards. You have to be thorough when selecting materials to use to guarantee patient safety and device performance.
So what are the key factors to take into consideration?
To develop high-quality medical equipment, mechanical strength, biocompatibility, and corrosion resistance are necessary. This is because medical equipment and tools frequently go through a lot before, during, and after they are used.
If they have corrosion resistance, they can withstand the rigorous sterilizing procedures. They can also remain in good condition even after coming into contact with various fluids. If they have high mechanical strength, they can endure great pressure. If they offer biocompatibility, they lower the possibility of tissue responses or rejection.
Three materials come to mind when we talk about these qualities. They are duplex stainless steel, SUS304 stainless steel, and SUS316L stainless steel.
How do these differ from conventional-grade materials?
In the case of duplex stainless steel, it offers a special combination of increased corrosion resistance and high strength. With SUS304 stainless steel, there is flexibility and affordability that performs well in applications with mild corrosion requirements. What about devices exposed to hostile environments or body fluids? For that purpose, the best choice is SUS316L stainless due to its exceptional corrosion resistance.
I. Duplex Stainless Steel (DSS)
Duplex stainless steel’s structure can be described as distinctive. Why? Because it consists of about equal proportions of austenite and ferrite phases. As a result, it has superior mechanical qualities. It is perfect for demanding applications since it is stronger and more durable than typical austenitic grades.
It also has remarkable resistance to corrosion. It can withstand pitting and stress corrosion, especially in hostile situations where human fluids are present. This makes it an excellent option for implants and surgical tools. Moreover, its great strength enables robust yet thin designs, reducing weight and enhancing surgical instrument mobility.
It offers some economic benefits as well. Its long-term stability minimizes the risk of replacements due to corrosion. This reduces overall healthcare costs. We can say that while it has a slightly higher upfront cost compared to some other grades, this is often offset by its extended lifespan and lower maintenance needs.
II. SUS304 stainless steel
SUS304 is composed of around 8% nickel and 18% chromium. Its exceptional resistance to corrosion can be attributed to this mixture, which qualifies it for environments with little chemical and biological fluid exposure. It is also renowned for having outstanding machinability. It makes the straightforward manufacture of complex medical equipment with precise shapes possible.
Thanks to SUS304’s properties, it is suitable for manufacturing a range of surgical and dental instruments, such as forceps, retractors, scalpels, dental drills, dental syringes, and dental mirrors. It offers resistance to corrosion and the ability to maintain sharpness. Its workability is also crucial for dental drills and other instruments requiring accurate machining.
III. SUS316L Stainless Steel
SUS316L stainless steel has reduced carbon content. It has exceptional durability and protection against rust. It also contains lower levels of carbon, reducing the chance of carbide buildup and increasing its strength when exposed to high temperatures. The combination of excellent corrosion resistance and ability to withstand pitting and crevice attacks makes SUS316L the preferred material for top-quality medical equipment.
For example, cardiac stents and orthopedic implants depend on the strong characteristics of SUS316L. The implants are able to endure continual pressures in the body due to their high strength. At the same time, its ability to resist corrosion is especially effective in environments high in chloride, such as blood, reducing the chances of implant failure. It also demonstrates outstanding biocompatibility, decreasing the likelihood of negative tissue responses and guaranteeing the extended effectiveness of these essential medical devices.
IV. Comparative Analysis
To select the right materials for medical devices, you have to carefully examine your options. You should analyze the unique benefits and drawbacks that each has.
Let us look at duplex stainless steel first. As mentioned above, it is the best choice when it comes to both strength and resistance to corrosion. It is perfect for bone plates that are subject to high stress. Unfortunately, it has a couple of drawbacks. It has a higher cost and complex processing techniques.
Next, we examine SUS304 stainless steel. Yes, it excels in terms of affordability and ease of machining. That is why it is a popular option for general surgical instruments that are exposed to moderate amounts of fluid. However, it offers lower strength.
Lastly, there is SUS316L stainless steel. It provides high strength and better resistance to pitting in chloride-rich conditions such as blood. This feature is ideal for advanced implants such as cardiac stents. This is the reason why it is considered the bridge that closes the gap. However, it has one negative. Compared to SUS304, its ease of machining is slightly less ideal.
Understanding the specific requirements of the application is essential. Surgical instruments with low stress and moderate fluid exposure can take advantage of SUS304’s low cost and easy machinability. On the other hand, if implants or devices are subjected to high stress or harsh bodily fluids, they require the impressive strength and corrosion resistance of SUS316L or duplex stainless steel. Through thoughtfully evaluating the pros and cons of each choice, you can make educated decisions that result in durable and trustworthy medical equipment.
Conclusion
Duplex stainless steel, SUS304, and SUS316L form the backbone of numerous medical devices. They each offer unique strengths. Duplex steel excels in high-stress implants, SUS304 is great for general surgical instruments, and SUS316L in harsh environments for its biocompatibility and resistance in harsh environments. The appropriate choice directly impacts patient safety, device performance, and long-term functionality. As medical technology advances, these materials hold immense potential. Innovations in processing techniques could unlock the wider application of duplex steel and push the boundaries of what’s achievable in medical device design and manufacturing.
Appendix
| Duplex Stainless Steel | SUS304 | SUS316L | |
| Composition | Approximately 50% ferrite and 50% austenite phases | Approximately 18% chromium and 8% nickel | Low-carbon variant of SUS316 stainless steel |
| Properties | Excellent mechanical strength and toughness; Exceptional corrosion resistance | Good corrosion resistance; Excellent machinability | High strength and high corrosion resistance; Excellent biocompatibility |
| Applications | Surgical instruments, orthopedic implants, high-pressure medical equipment. | Scalpels, forceps, other surgical instruments, dental drills | Cardiac stents, orthopedic implants, other high-end medical devices exposed to harsh bodily fluids |
| Advantages | High strength, superior corrosion resistance, long-term stability | Affordable, readily available, good machinability | Superior strength, excellent corrosion resistance, biocompatible |
| Limitations | Higher upfront cost compared to some other grades, requires specialized processing techniques | Lower strength compared to duplex stainless steel, moderate corrosion resistance | Slightly lower machinability compared to SUS304, higher cost than SUS304 |
External links:
https://en.wikipedia.org/wiki/Duplex_stainless_steel
https://matmatch.com/learn/material/sus304-stainless-steel-ss304
https://innovate.kgi.edu/blog/a-deep-dive-into-the-manufacturing-of-medical-devices
