by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

PTFE Rotary Shaft Seals for Medical Devices

Selecting the right rotary shaft seal for a medical application involves many different factors including sanitation and sterilization concerns, material compliance to both national and international standards, and patient safety. While some medical applications still depend on elastomeric sealing solutions, FDA-approved PTFE rotary shaft seals provide far more benefits.

Rotary Shaft Seals in Medical Applications

Rotary shaft seals are tasked with retaining media and protecting from outside contamination in the presence of rotating or swiveling motion. In the context of medical devices, sealing solutions are critical for the reliable operation of many different devices in hospitals rooms, treatment centers, operating rooms, and at-home health.

Medical devices that depend on rotary shaft seals include …

  • Tissue cutting tools
  • Biopsy tools
  • Ablation equipment
  • Surgical wash units
  • Surgical equipment
  • Blood pumps
  • Infusion pumps
  • Dialysis equipment
  • Endoscopes
  • Disposable stent handpieces
  • Hospital beds
  • Patient lifts

In each of these devices, the failure of a seal could lead to serious patient injury or even death. There is no room for mistakes in choosing the right seal and appropriate seal material.

Choosing a Sealing Solution for Medical Applications

When choosing a rotary shaft seal for a medical application, there are several key characteristics that must be considered. It is important to take into account the pressures involved, including not only the potential for high pressures but vacuum pressures as well. Temperatures, including operating temperature and the possibility for temperature spikes, are also critical, as well as the type of media, lubricant, and cleaning chemicals the seal will be in contact with. The expected PV value, based on pressure and speed, will also significantly affect the type of seal and material chosen. And no less important is the choice of an appropriate medical grade seal material.

Medical Grade Seal Materials

Medical applications, whether in vitro or not, severely constrain the choice of seal material. Selecting the right material for a seal involves compliance with various national and international regulations along with the properties discussed in the previous section. Medical grade materials are in compliance with the appropriate USP (U.S. Pharmacopeial Convention) standards related to medical materials. 

In the United States, these standards are enforced by the FDA (Food and Drug Administration) but are also used in over 140 other countries. These standards look at both the biological response for materials that either come into direct or indirect contact with medical patients, and medical grade materials are usually USP Class VI compliant. Such materials are believed by the scientific community to significantly reduce the risk of harming a patient due to a reaction to a toxic material.

ASTM International (American Society for Testing and Materials) also has standards that relate to medical devices, including ASTM F1980-16 Standard Guide for Accelerated Aging of Sterile Barrier Systems for Medical Devices. There is also the ISO (International Standards Organization) 10993 standard that focuses on patient safety and may apply to rotary shaft seals depending on their application. 

PTFE Rotary Seals

FlouroSeal PTFE rotary shaft seals offer several advantages over other medical-grade seal materials, including significantly lower friction that means more efficient energy usage, and less heat generation. A smaller coefficient of friction also means reduced breakout friction and a much lower startup torque. The fact that PTFE is self-lubricating means dry running is possible, which is especially beneficial in applications where lubrication can be an issue. 

PTFE has excellent wear characteristics, dimensional stability, and excellent performance even in extreme temperatures (e.g., a continuous operating temperature of 500°F). And because of PTFE’s chemical compatibility and thermal performance, PTFE seals can handle exposure to hot water, steam, and aggressive cleaning chemicals used in sanitation and sterilization procedures. And because PTFE is non-wetting, it can be self-cleaning in some situations.

FlouroSeal PTFE is available in grades that are FDA and USP Class VI compliant, making them an excellent choice for rotary shaft seals used in medical devices. In addition, the type of seal is not limited by using PTFE, either. Not only are PTFE rotary shaft seals available in hydrodynamic, plain, and multi-lip configurations, but they are also available as spring-energized seals.

Limitations of PTFE

PTFE does have its limitations in medical applications. For example, high-energy radiation can cause a breakdown of its molecular structure, making it inadvisable to use in applications that depend on radiation for sterilization. 

It is also important that the shaft meet certain conditions to ensure the longevity and performance of the seal. Most experts recommend a surface finish of 2 and 16 RMS with a Rockwell hardness between 55C and 65C, but this can vary depending on the PTFE additives used.

Conclusion

FDA-approved PTFE medical grade materials are an excellent choice for rotary shaft seals for medical devices. Low friction, chemical compatibility, thermal properties, dry running, and dimensional stability all support its use for even the most demanding medical applications. If you are working on a medical sealing solution, contact the experts here at Advanced EMC. We can help you navigate the various regulations and find a reliable, safe rotary shaft seal.

by Jackie Johnson Jackie Johnson No Comments

A Growing Medical Market

There are many factors that contribute to the rapidly growing medical plastics market. There is an increased demand for advanced medical devices, a rise in disposable income and changing lifestyles, and a demand for affordable and efficient healthcare systems.

These and more are currently driving the medical market, with a current estimated net worth of 22.8 billion USD.

And it is only growing.

Experts suggest that by 2024, the market will grow to a whopping 31.7 billion, with a CAGR of 6.8%.

Medical Plastics Market

Source: Markets and Markets, Medical Plastics Market

Applications of Medical Grade Plastics

Plastic packaging is widespread across many industries, but no more so than in the medical field. Within the next few years, packaging is expected to grow at a CAGR of 7.8%, due to the increased use in pharmaceutical packaging, device packaging, and more.

Surprisingly though, it is devices such as medical implants and machinery that are generating the largest revenue and driving the industry forward. A perfect storm of an ever-growing population and an increase in chronic diseases, along with the lower manufacturing cost of these devices has led to the largest growth in the medical plastics industry.

Global medical polymers market

Source: Grand View Research, Medical Polymers Market Size

An Industry Standard

Since the 1980s plastics have dominated the medical device industry on account of their low manufacturing cost, flexibility, ease of replacement, and low risk of infection.

Plastics also provide radiolucency, enable light-weighting, and reduce stress-shielding. Because they are radiolucent, polymer-based surgical devices allow surgeons to have an unobstructed view.

All these combine to make medical-grade plastics the gold standard in the industry. Which in turn creates a very lucrative market.

In Conclusion

The medical-grade plastic industry has taken off in an incredibly short amount of time. With increasingly easy to manufacture products coupled with an ever-expanding market, the industry will only get bigger over time. Want to learn more? Contact us today! 

 

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Medical Engineering in the Age of COVID-19

Medical Engineering in the Age of COVID-19

Due to the COVID-19 pandemic, there has been an increase in worldwide demand for thermal scanners, respirators, and ventilators. This has been accompanied by an increased need for medical disposables such as gloves, respirators, medical masks, face shields, single-use syringes, and drapes. As a result, medical engineering and manufacturing both have temporarily shifted their focus and the results are fascinating.

3D printed hand sanitizer clasp

Additive Manufacturing

Shortages of some items have led to innovative design and manufacturing, much of it involving additive manufacturing using polymer materials. For example, Old Dominion University has been 3D printing masks and mask components made from PLA and designed so that they can be easily sterilized and reused. Europe has already seen companies in the 3D printing industry volunteer their equipment and knowledge to aid in manufacturing replacement parts for critical equipment such as oxygen and respirator valves, and many other countries are doing the same thing. 

Ventilator Designs

Many countries, including the United States, are worried about a potentially deadly shortage of ventilators. Various technology firms worldwide such as Nvidia are working to design critical care devices that can be produced both quickly and inexpensively. NASA has been given permission to start production of their emergency use ventilator that can be manufactured and built quickly, with the only drawback being its limited lifespan. 

In addition, ventilator manufacturers such as Medtronic have ramped up production and publicly shared their design specifications for one of their ventilator models so others can help meet this critical need.

Innovation

Engineers all over the world are looking for ways to make the treatment of COVID-19 patients easier and safer for medical personnel. For example, engineers in the Boston area have teamed up local doctors to develop a 3D printed bracket that will hold the tube and respirator hookup together in ventilator patients. The goal is to prevent release of the COVID-19 virus into air when these connections come undone, as they often do. 

Others at Boston University are looking at polymer nasal swabs that will do a better job of collecting mucus for COVID-19 tests, which could increase the reliability of testing and help with testing material shortages. At the Oxford Institute of Biomedical Engineering, engineers are leveraging wearable technology to allow nurses to track the vitals of COVID-19 patients who are not on ventilators and thus must remain mobile to recover.

Conclusion

The COVID-19 pandemic has changed how much of the world lives, and has affected a shift in the focus of many engineers. Trademarks of this shift include the use of additive manufacturing for PPE and replacement parts for life-saving equipment, a fresh look at ventilator designs that emphasizes manufacturability and availability, and the birth of innovative approaches to medical issues related to the pandemic. And, in this midst of this, companies like Advanced EMC are still working hard to make available the right polymer seals and bearings needed for medical equipment. 

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Canted Coil Springs: Benefits for Medical Applications

What is a Canted Coil Spring?

Canted coil springs (also known as cant or slant coil springs) are not your typical spring, and this becomes obvious when you take a look at the three different types of tasks they support:

  • Acting as a mechanical connector
  • Energizing seals for better performance
  • Providing EMI/RFI shielding
  • Serving as a multiple contact point conductor

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