PEEK Injection Molding – Processing Tips for High-Temperature Materials
The idea of processing PEEK (polyetheretherketone) or other high-temperature resins can cause nerve tremors in many castings. I know that as a casting machine who learned craftsmanship through continuous diet or PP and PE closures due to its low melting point temperature and cold form, my first PEEK experience was a little sad. But since then, I’ve realized that PEEK is just another thermoplastic resin, like the rest, that can be cast safely and efficiently, with a few precautions.
PEEK (Polyether ether ketone) is widely believed to be one of the best-performing thermoplastic materials on the market, and its final properties not only justify the trials and tribulations that may occur during processing. PEEK is a linear aromatic semi-crystalline thermoplastic with excellent abrasion, chemical, and hydrolysis resistance. It has very low flame/smoke toxicity and excellent electrical properties, which in many cases eliminate the need for additives.
PEEK runs at high melt temperatures up to about 720 ° F and both the extruder tube and the controls should be able to do so. For many molding machines, high thermal insulation software is an option and I recommend ceramic high-temperature bands whenever possible. No special screws and barrels are usually required, but hard units should be considered when running filled PEEK resins. Usually, we use check valve slip rings, GP or Eliminator (TM) tips, and we do not recommend ball checks or stop nozzles.
The hot form is key to achieving crystallinity in PEEK components. Purification of PEEK allows the color change to develop from a translucent and solid crystalline state. If the mold is too cold (ie not hot enough), the discoloration or partial transparency of the components is retained and the quality of the final product is compromised. In most cases, the mold should be between 350 ° F and 450 ° F. This is a steel temperature and requires oil or cartridge heat to maintain this level. Complex components may require better temperature control, making oil the preferred option. We also recommend the use of a thermocouple to control and control the temperature of the steel.
These molds are specifically designed to run high-temperature materials that take into account the stretch, finish, washer, and steel types from the outset. Insulating boards between press plates and casting plates are mandatory. The preferred steel grade depends on whether or not the resin uses a scouring filler, but must have a hardness of at least 52-54 Rc.
The resin must also be very dry in order to be well processed and to achieve the desired end properties. This means that the resin has a moisture content of at least 0.02%. We generally recommend drying the resin at 300° F for at least 3 hours. We also recommend the use of a moisture analyzer to ensure drought.
PEEK molding can be quite expensive, but it must be able to use 30% dry primary rewound on filled PEEK and 10% on charged PEEK.
When casting PEEK, safety must be a priority, both during rinsing and during casting. Wear safety goggles and/or face shields, Kevlar or Kevlar/stainless steel sleeves and heavy cotton gloves when pouring into and entering the mold.
As you prepare for the PEEK experience, examine it thoroughly with your resin supplier. The above information is based on my experience but can only be used as a reference. Also, be sure not to disregard recognized scientific principles when working with any thermoplastic material. In a somewhat general sense of formatting, PEEK’s experience can and should be rewarded.
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