Injection molding is a versatile process used to make many kinds of products, including medical, aerospace, and machinery parts. In injection molding, a raw material is melted and injected into a mold where it is allowed to cool and solidify into a final product. This process is highly customizable and capable of creating a part that meets any requirement. Polyether ether ketone, or PEEK, is an engineering thermoplastic with exceptional performance. It has good resistance to a wide range of chemicals and is biocompatible, meaning it can be safely sterilized for medical applications. PEEK is also very durable and can withstand high temperatures.
In PEEK injection molding, the most critical factor is temperature control. This material requires a higher melting point than other plastics and can have different shrinkage rates depending on whether it is crystalline or amorphous. To minimize warping, the temperature of the melt should be monitored and controlled to within 10°C of the target processing temperature. Using a high-quality hot-runner system is another way to ensure optimal results.
Because of its strong chemical resistance, PEEK is used in a variety of industrial applications, from medical devices to aircraft and machinery. It has a wide operating temperature range and is self-lubricating, which helps it resist wear, even when used for long periods of time. PEEK is also very resistant to corrosion and can tolerate radiation used for sterilization.
PEEK’s chemical resistance is a result of its molecular structure. It is a semi-crystalline plastic that has alternating ordered (crystalline) and randomly ordered (amorphous) segments. This enables it to resist a large number of chemicals, with the exception of acids.
During the injection molding process, PEEK’s crystalline segments are melted and deposited into the mold. The amorphous segment is then formed around them, which makes it difficult to remove the molded part from the mold without damage.
To avoid this, it is important to use a large injection gate, which will allow the molten plastic to flow evenly into the mold cavity. In addition, the corners of any vertical features should be rounded to prevent stress concentrations in the finished part. Finally, it is recommended to add a draft angle to the vertical walls of the mold to help the ejection of the molded part from the mold.
Injection molding of PEEK requires extra precautions compared to other plastics, such as the use of big gates and the application of heat to the mold. These additional steps are necessary to ensure the success of the production run. To learn more about the proper design of injection molded parts, Fictiv’s Injection Molding Design Guide is available to download. peek molding