Plastic profile brittle extrusion process unreasonable reasons
Head pressure is insufficient
On the one hand and mold design; the other is the proportion of the feed and temperature settings, the pressure is insufficient, the material density is poor, it will become loose tissue plastic brittle phenomenon, then adjust the metering feed speed And extrusion screw speed so that the head pressure control in the 25Mpa-35Mpa between.
Excessive or insufficient material
This is related to the process temperature setting and feeding ratio. The temperature setting is too high to cause the material to be plasticized. Some of the components with low molecular weight in the component will decompose and evaporate. The temperature is too low. Fully welded, the molecular structure is not strong, while the feed ratio is too large cause the material heating area and shear increases, the pressure increases, easily lead to plastic; feeding ratio is too small material heating area and shear reduction, Resulting in less plasticized, whether it is plastic or plastic surgery will cause plastic profiles crisp cutting collapse phenomenon.
The low molecular weight of the product is not discharged
There are two general approaches to the production of low molecular weight components in the product, one at the time of hot blending, which can be vented through the dehumidification and exhaust system during hot blending, partly by partial residual and extruded heat Water and hydrogen chloride gas. This is usually through the host exhaust section of the forced exhaust system to force the discharge, the vacuum is generally between -0.05Mpa-0.08Mpa, not open or too low, will remain in the product of low molecular weight, Resulting in mechanical properties of plastic profiles decreased, resulting in plastic profiles crisp.
