PEEK (Polyether Ether Ketone) is an engineering thermoplastic with excellent thermal and mechanical properties. It is self-lubricating and highly resistant to corrosion, and it can be molded into parts with complex geometry. PEEK is also lighter than metal and can provide strength comparable to metal parts at half the weight.
However, injection molding PEEK requires high processing temperatures that not all facilities can handle. There are also cooling requirements that must be met to prevent warping and other defects. These limitations have made injection molding PEEK a challenge for many companies that want to produce PEEK parts for industrial applications.
Injection molding PEEK requires special equipment because of the high process temperatures needed. Choosing the right machine is essential to avoid defects such as silver streaks and pores, which can detract from the quality of a finished part. In addition, selecting the right needles and nozzles is important to ensure proper injection. Using the wrong injection nozzle and needle can lead to poor flow or inconsistent parts.
To prevent these defects, manufacturers should choose a peek injection molding machine from a reputable supplier. In addition, the machine should have a standard processing temperature range of 350degC-400degC. In addition, a barrel blanket can add extra heat insulation to reduce energy costs and keep the temperature closer to the target processing range. Injection pressure is another factor that can cause a peek injection molding defect. The injection molder should ensure that the nozzle and barrel remain at a safe distance during the injection process to reduce the chance of the PEEK melt colliding with the air and solidifying too quickly.
A good peek injection molder should use a nozzle and needle that are specifically designed for this type of plastic. In addition, the nozzle and needle should be lubricated to minimize friction between them. Injection molding PEEK with a nozzle that is not properly lubricated can result in cold material defects, silver lines, and fusion marks.
Uneven cooling is a common problem for PEEK injection molded parts. This occurs when some parts cool at a faster rate than others. This causes a mixture of amorphous and crystalline regions in the finished product, which is visible as an uneven coloration.
In order to avoid these injection molding problems, the injection moulder should use a core injection system to control the flow of the plastic. This will allow the polymer to fill the voids of the mold and increase the strength of the injection molded part. Additionally, the injection molder should set the injection temperature and pressure to the optimal level for PEEK parts to achieve the desired tensile strength. In general, the injection temperature has the largest impact on tensile strength, while the injection pressure and the core injection speed have a smaller effect. The results of orthogonal experiments show that the optimal injection temperature and pressure for injection molding PEEK is 373°C and 11 MPa, respectively. If these factors are not achieved, the tensile strength of injection molded PEEK parts will be significantly lower than they should be.