Peek is a semi-crystalline, high-performance thermoplastic that maintains its superior mechanical properties even at high temperatures. It has a glass transition temperature of 143°C, a melting point of 343°C, and excellent chemical resistance. Injection molding is an effective manufacturing method for peek, but it requires special molds and equipment to ensure a successful outcome. Injection molding manufacturers should take these five factors into account to avoid problems during production.
During injection molding, the plastic is injected into a cavity under pressure using an injector. This pressure forces the plastic into any gaps or holes in the mold, resulting in a well-formed part. Injection molders must use a high-quality injection machine and follow the proper processing guidelines to prevent defects like flash and runners.
The first step in peek injection molding is to dry the PEEK pellets thoroughly before processing. This prevents moisture from causing oxidation, which affects the chemistry of the material and reduces its strength and durability. The pellets should be dried to a moisture content of less than 0.02%, which can be achieved by placing the pellets in a circulating oven at 160°C for 2 to 3 hours.
Injection molding machines must be equipped with a high injection pressure and temperature to successfully mold peek. The injection pressure is determined by the mold’s cavity size and the amount of material displaced during injection. The injection speed must also be consistent and stable, and the mold should be kept clean. Moreover, the injection mold should be designed with big gates to allow the plastic to fill and pack out the component.
Another important aspect of PEEK injection molding is the use of a draft angle on all vertical walls. This makes ejection from the mold easier and prevents stress concentrations that can weaken the part. Ideally, the draft angle should be 5o deg, but larger angles may be necessary for taller features.
In addition to its excellent mechanical properties, peek is a highly durable and biocompatible material. It is a popular choice for manufacturing medical devices, automobile and aerospace components, and machinery parts. It can withstand harsh environmental conditions, including radiation and chemical exposure. The material can be mass-produced using injection molding without the need for metal machining or thermoset curing, saving time and money. Additionally, it has electrical insulation and corrosion-resistance properties and is FDA compliant for food contact. The chemical structure of PEEK consists of repeating units of ketone and ether bound benzene rings. This unique composition allows the material to tolerate a variety of chemicals, radiation, and extreme temperatures. Because of these exceptional properties, it often outperforms metals in harsh environments and is used in products like aircraft and car parts, medical devices, and semiconductors. The material can be sterilized with gamma and UV radiation, without damaging its physical or chemical integrity. It can also be color pigmented, although this alters the mechanical properties. It can be modified with fillers, such as carbon fiber and glass fiber, to increase its rigidity and strength, or with lubricants for enhanced wear resistance. peek molding