Injection of high-temperature group plastics

High-temperature engineering plastics do not require specially-designed HR systems. The following conditions should be borne in mind, however  

The following general recommendations for HR system design then arise  

Fluoroplastics feature high viscosity combined with a low resistance to shear stresses. Large channel diameters and very large gates, with a diameter of as much as 5 mm, are recommended [7]. This requires nozzles with a valve pin to be used. In a plasticised state, the melt has a strong corrosive effect on steel (chemical reaction of fluorine and iron). Steel with a high nickel content is therefore recommended, or else nickel coatings. To improve heat conduction, internal copper beryllium alloy inserts are used in the nozzles, which are pressed into elements made of hardened nickel steel. 

A seal with rectangular, not round cross-section should be used to seal the contact between nozzle and manifold. 

Polyarylates PAR, polyarylester (PAE), aromatic polyester (APE), HTPC. The viscosity of these plastics is even greater than that of PC, and does not diminish as the shear rate rises. The channels should have relatively large cross-sections. The minimum gate diameter 

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