Views:29 Author:Vera Publish Time: 2017-06-21 Origin:Site
1. Reasons for the high black spots
The raw material itself is of poor quality;
Screw overheating, causes increased carbonization of materials; then the carbon compounds were brought to the material, resulting in black spots;
Screw heavy shear, causes increased carbonization of materials; then the carbon compounds were brought to the material, resulting in black spots;
The diehead pressure is too heavy (including the plug, too much the filter, too low temperature of the diehead, etc.), and the back material is too much, causing material carbonization increased, carbonized compounds were brought to the material, resulting in black spots;
The life length of the machine is long, the gap between screw and barrel is increased, the adhesion of the barrel wall is increased, and the adhesion is gradually brought to the material strip with extrusion process, which causes the black spot to be more;
For a long time no clean for the natural exhaust and vacuum vent, the accumulation of carbon increased, and then was brought to the material by continuous extrusion, resulting in black spots;
External environment or man-made caused by other impurities mixed, resulting in high black spots;
The diehead (including the outlet and the internal dead) did not clean up, resulting in high black spots;
The outlet is not smooth enough (such as some shallow troughs and potholes, etc.), the material maybe accumulate, and with the extrusion time, will be gradually carbonized, and then be brought out, resulting in black spots;
Part of the screw elements damaged (such as missing angel, wear and so formed dead ends), resulting in the material in the corner carbonization increased. In the subsequent continuous extrusion process, is gradually brought out of the material, cause black spots;
Sluggish of the natural exhaust and vacuum vent, cause the material in the screw cabonization, resulting in more black spots.
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