Tips for Machining PEEK Plastic
Polyether ether ketone (PEEK) is a colorless organic thermoplastic polymer used in a variety of industries. Three key characteristics of PEEK plastics are their strength, wear resistance, and biocompatibility. They are softer than most metals but stiffer than most plastics. Some of PEEK polymers’ other unique characteristics are:
- Low coefficient of friction
- Wear resistance
- Mechanical and chemical resistance
- Low moisture absorption
- Abrasion resistance
PEEK plastics are excellent for applications that require strength and stability under consistent high temperatures (500°F/260°C). PEEK polymers are often used as components in equipment parts, including pistons, pumps, electrical cable insulation, and bearings. There is also a rise in the use of PEEK for medical implant device components, such as dental healing cups, spiked washers, and spinal implants. Additionally, its advantageous properties are causing PEEK to gain increasing popularity in the aerospace, automotive, and chemical process industries.
PEEK for industrial components
There are two basic grades of PEEK: industrial grade and medical grade. Industrial grade PEEK keeps its mechanical properties at high temperatures. It is a flame retardant material with abrasion resistance, high impact strength and a low coefficient of friction. The industrial grade version is often used in the aerospace, automotive, chemical, electronics, petroleum, and food and beverage industries.
PEEK for medical components
Medical grade PEEK has the same properties as industrial grade PEEK plus more. On top of all the properties of industrial grade PEEK, medical grade PEEK possesses biocompatibility and high chemical resistance. It also has compatibility with various sterilization methods and is naturally radio translucent, meaning it is invisible in X-ray photographs. Its properties make it an ideal material for manufacturing components for medical implants.
How to machine PEEK plastic
Industrial and most medical grade PEEK polymers are machined in about the same way. However, medical grades reinforced with carbon fiber must be approached differently. For instance, this material should be heated just prior to machining in order for it to soften, reducing cutting tool wear.
Here are some basic tips to be aware of when machining PEEK polymers:
- For Machining, PEEK materials usually come in the form of rods, plates, or injection molded blanks.
- Before machining, stress relieve PEEK plastic through an annealing process to decrease the possibility of surface cracks and internal stresses.
- As PEEK polymers are softer than most metals and stiffer than most plastics, fixturing is crucial.
- While PEEK can endure high temperatures and has a high melting point, it still requires coolant. Avoid overheating and surface melting by providing sufficient coolant such as pure water.
- PEEK grades are abrasive on tooling, especially if they are reinforced with carbon fiber and glass.