Common Problems and Countermeasures of Plastic Granulation Modification Processing(3)

Analysis of the hollow problem of granulation

 

Poor exhaust:

Exhausting of gas or steam is not smooth: due to poor natural exhaust or vacuum exhaust (the reasons maybe material itself is too heavy; may also be the decomposition of additives, such as flame retardants; or vacuum blockage, or vacuum too small or leakage, or vacuum gasket cushion too high), resulting in the existence of gas(vapor) in the granules and forming hollow.

Poor plasticization

The processing temperature is low, cause the material can not fully plasticizing. This may results in the pellet hollow, or even worse, may causes the broken strip;

 

Too much low melting point additives (including EBS or pets). If the in screw shearing is weak, It may results in poor plasticizing, and formation of hollow;

 

Too much low melting point additives (including EBS or pets). If the screw and barrel gap increasing or screw shear be weak, It results in poor plasticizing, and formation of hollow.

 

Too low water temperature. The cooling water temperature is too low, the material is contracted by water, causes the shrinkage hole. In general, crystalline plastics (such as PP, PA, PBT, etc.) should be used low water temperature, amorphous plastic (such as ABS, ABS, HIPS, etc.) using high water temperature.