Causes and treatment methods of plastic hooks with flying edges and bubbles

Causes and treatment methods of plastic hooks with flying edges and bubbles.

The plasticizing capacity of injection molding machine is small. When the plastic hanger hook quality exceeds the injection molding machine practice greater injection quality, the significant amount of material is inadequate. If the quality of the plastic hook is close to the practical injection quality of the injection molding machine, there is a problem that the plasticization is not sufficient, the material is short of heating time in the barrel, and the results can not timely supply the appropriate molten material to the mold. This situation only replaces the large capacity of the injection molding machine to deal with the problem. Some plastics such as PP hook material melting scale is narrow, the specific heat is larger, the injection molding machine with large plasticizing capacity can ensure the supply of materials.

The temperature of the thermometer is not true, high and low, and the temperature of the material is too low. This is due to the failure of temperature control devices such as thermocouple and its line or temperature difference millivoltmeter, or due to the aging or burning of the heating ring far away from the temperature measurement point, heating failure and not found or not timely replacement.

Nozzle inner hole diameter is too large or too small. If it is too small, the specific volume of the strip will increase due to the small flow diameter, and simple cooling will block the feed channel or consume the injection pressure; If it is too large, the flow cross-sectional area is large, the unit area pressure of the plastic entering mold is low, and the composition force is small. A non-Newtonian plastic hook, such as ABS, cannot reduce the viscosity because it does not obtain large shear heat, which constitutes the difficulty of filling. Poor cooperation between nozzle and main channel inlet often causes mold overflow and mold filling dissatisfaction. The nozzle's own activity resistance is very large, or there are foreign bodies, plastic carbonized sediment obstruction; Spherical damage and deformation of nozzle or trunk channel inlet, affecting outstanding cooperation with the other side; Injection seat mechanical failure or deviation, so that the nozzle and the main flow channel axis tilt displacement or axial compression surface from; The ball diameter of the nozzle is larger than the ball diameter of the inlet of the main flow channel. Because the edge presents a gap, the axial pushing force of the nozzle will gradually increase under the overflow extrusion.

Plastic hook frit blocks feeding channel. Because the plastic hook is partially melted and caking in the hopper dryer, or the temperature of the barrel feed section is too high, or the plastic grade is not selected properly, or the lubricant contained in the plastic is too much, the plastic will prematurely melt in the inlet diameter reduction position or the deep groove of the screw starting end. The particle and the molten material bond with each other to form a "bridge", blocking the channel or enclosing the screw, and sliding in a circle with the rotation of the screw. Can not move forward, constitute the suspension of material supply or irregular shaking. This situation is only in the chisel through the channel, after the exclusion of material block to get the base treatment.

The injection cycle is too short. Due to the short cycle, the material temperature too late to keep up will also constitute a lack of material, especially when the voltage is shaken. The cycle should be adjusted according to the supply voltage. The adjustment generally does not consider the injection and pressure holding time, the first consideration is the adjustment from the completion of pressure holding to the time of screw back, not only does not affect the molding conditions, but also can extend or shorten the preheating time of the grain in the barrel.

【The advice comes from the Plastic slipper hook website】