The characteristics of nylon PA and the selection points of injection screw

Characteristics of nylon PA

The characteristics of PA are as follows: There are many types of crystalline plastics, different types, different melting points, and a narrow melting point range. Generally, the melting point of PA66 is 260~265°C. Low viscosity, good fluidity, relatively obvious melting point, and poor thermal stability. The water absorption is average.

Key points of screw selection for nylon PA injection molding

When selecting screws for PA injection molding, the following points should be paid attention to:

(1) Select a mutant screw with a length-to-diameter ratio of 18-20.

(2) The compression ratio is generally 3~3.5, in order to prevent overheating decomposition h3=(0.07~0.08)D.

(3) Because of its low viscosity, the gap between the check ring and the barrel should be as small as possible, about 0.05, and the gap between the screw and barrel is about 0.08. If necessary, depending on the material, the front end can be equipped with a check ring, shooting The mouth should be self-locking.

(4) Other parameters can be designed according to general screw.