Stock PEEK shapes like rods allow for thicker cross-sections and extended lengths, beyond what is possible with injection molding. PEEK rods can be extruded with cross-sections of 8 inches or more in diameter, and polymer converters have a full range of rod sizes available. Experienced converters will also be able to handle a diverse array of PEEK grades, including carbon-reinforced, or CFR PEEK. CFR PEEK is useful in medical applications that call for additional strength or stiffness.
The large majority of implantable PEEK devices are machined from PEEK rod stock. One reason for this is the polymer’s compatibility with modern machining methods.
PEEK’s Machinability Advantage
As a high performance polymer, PEEK can withstand the rigors of machining. In fact, PEEK is especially well-suited to precision machining, and is often used in conjunction with CAM processes. With CAM technology, device manufacturers can use 3D imaging to create customized PEEK devices that meet extremely tight tolerances. A popular application of PEEK and CAM is in dentistry, where dental device manufacturers use 3D images of patients’ bite patterns to create partial denture frameworks.
PEEK’s superb machinability is a significant reason why PEEK rod stock is in demand among device manufacturers.
What Are Some Additional Advantages of PEEK?
PEEK’s overall processability means it can be designed to fit into many roles, but it possesses additional advantages that make it an ideal biomaterial. Some of them include:
- Versatility – In its natural, unfilled state, PEEK possesses a flexural modulus that’s similar to cortical bone. This means PEEK is a frontline choice for interbody fusion cages and any application where the polymer must interface with native bone.
In applications where additional stiffness and strength are needed, CFR PEEK, mentioned above, can be produced by augmenting PEEK with chopped carbon fiber.
Some of PEEK’s other attributes, like its radiolucency, or transparency with imaging technologies, can be altered with other additives. Barium sulfate, for example, can make PEEK more visible on CT scans, MRIs and X-rays.
PEEK can also be extruded into extended lengths for medical tubing, which makes it a valuable material for cardiovascular devices and medical equipment.
- Biocompatibility – PEEK is a proven biomaterial, and has the test results and patient reports to support it. PEEK has passed the most demanding biomaterial safety testing available (USP Class VI and ISO 10993) and has also been in use as a spinal implant for 20 years. In that time, patient reports have not demonstrated concern with the polymer. In fact, PEEK is now the primary biomaterial for interbody fusion cages with its excellent safety record.
- Durability – PEEK is a high performance polymer, so its material properties are elite among medical plastics. Durability is a standout property of PEEK as it possesses excellent wear resistance, strong corrosion resistance and all-round strength. PEEK’s tensile strength, for example, is comparable to aluminum and cast iron when processed in its CFR form. PEEK’s pullout strength is remarkable, too, which is why it is incorporated into anchoring systems for trauma fixation and other devices.
PEEK’s resilience is also notable, as the polymer can withstand repeated compression and tensile forces without losing its shape or strength. This is also useful in dentistry, where PEEK components may be responsible for shouldering biting and chewing forces.
- Sanitary benefits – PEEK is also helping medical facilities in the fight against hospital-acquired infections, or HAIs. HAIs are a dire problem for hospitals, as the Centers for Disease Control and Prevention (CDC) states that nearly 100,000 people die every year due to a HAI.
To stop HAIs from emerging or spreading from person to person, hospitals are increasingly investing in single-use instruments. Single-use instruments are disposed of after they are used with a patient, removing the chances of spreading an infection entirely. Some instruments, like medical tubing, are notorious for being difficult to completely clean, and PEEK, along with other medical plastics, offer an alternative.
- A bright future – PEEK is one of the most promising biomaterials for the future of medicine, and engineering firms are already developing the polymer in interesting ways. PEEK was first used in spinal implants, so it’s no surprise that improved PEEK based spinal implants are being introduced to the market. New implants utilizing advanced PEEK technologies demonstrate more effective osseointegration, which is key for interbody fusion cages. This new generation of improved PEEK implants is driven by improvements to the implant’s structure and composition.
Even though PEEK is found in spinal fusion, orthopedic, dental, cardiovascular and trauma fixation applications, it is one of the newest biomaterials available. With time, PEEK will be improved on further and integrated into additional medical procedures.
PEEK rods offer a convenient way for device manufacturers to machine precise devices and components from PEEK stock shapes. Experienced PEEK converters will have a variety of PEEK grades and rod diameters available, so no matter your material needs, there is PEEK stock ready and waiting.