PEEK has long been a highly regarded engineering polymer for an almost infinite variety of applications. One of the reasons it remains popular is its processability: PEEK is well adapted to a number of polymer processing techniques. In this post, we are going to discuss four processing methods for manufacturing components from PEEK.
Method 1: Compression Molding
In compression molding, a charge of plastic material is preheated and placed in a mold cavity. The mold is closed under pressure and heated. After the part has cooled, it is taken from the mold and flash is removed. This process works very well for reinforced polymers and is a standard manufacturing method for making parts from PEEK.
Compression molding produces parts with a good surface finish. Setup time is pretty quick, and the setup costs are relatively low. It cannot handle geometries with undercuts, however, and the processing time and part consistency are not as good as injection molding.
Method 2: Injection Molding
Injection molding is one of the most common processing methods for producing plastic parts, PEEK included. In injection molding, molten plastic is injected (i.e., forced) at high pressure into a die. After cooling and solidification the part (or parts) is removed from the die. Minimal post-processing is required, and usually takes the form of trimming of flash and excess plastic.
Injection molding is good for thin-walled parts and can produce complex parts with fine detail. Injection molding results in a part with a good surface finish and excellent dimensional accuracy. Benefits, from a production point of view, include a high production rate and low labor costs. Drawbacks are high tooling, the possibility of long lead times, and high costs.
Method 3: Extrusion
Extrusion is used to make polymer parts that have a constant cross-section, including tubes. This is another commonly used manufacturing process for PEEK parts. Heated plastic is forced at high pressure through an open die.
Production costs tend to be quite low, setup times are quick, and initial costs relatively low. However, the precision is not as high as would be achieved with injection molding and it only works with parts that have a uniform cross-section.
Method 4: Centrifugal Molding
In centrifugal casting (sometimes called rotational molding, centrifugal molding, or rotomolding), the molten polymeric material such as PEEK is placed into a mold and sealed. The mold and polymer are heated to the point that the polymer is in a liquid state. Then the mold is rotated on multiple axes. Centrifugal forces cause the polymer to be distributed evenly on the inside surface of the mold. This manufacturing method can be used to make complex, hollow parts with thin walls and very low residual stresses. It works very well with reinforced materials.
Centrifugal molding provides an excellent surface finish with limited tooling costs. It is well adapted to both short and long production runs. Its primary drawbacks are lack of precision compared to injection molding and low production speed.
Not only is PEEK known for its strength, low friction, chemical compatibility, and excellent wear properties, but it can also be used with several different manufacturing processes. Its manufacturability makes it suitable for prototypes, custom one-of-a-kind parts, or large production runs. Its processability also makes it easier to fit into a project budget.
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