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Common problems and solutions in the production process of extruder
1.Plastic scorch
Plastic scorching is a common quality defect in the plastic extrusion process,which is manifested as:excessively high temperature display;There is a lot of smoke and a strong irritating smell at the die mouth of the machine head,and in severe cases,there may be a popping sound;Extruded plastic layer with charred particles;There are continuous bubbles at the adhesive joint;The main reasons for the occurrence of annotations are:
1.Temperature control reaches the temperature of plastic thermal degradation at an ultra-high level;
2.The screw has not been cleaned for a long time,and the accumulated burnt material is squeezed out with the molten plastic;
3.Excessive heating or shutdown time can cause the plastic inside the barrel to decompose due to prolonged heating;
4.Loss of control or misalignment of temperature control instruments,resulting in high-temperature decomposition;
5.The cooling system of the extruder was not turned on,causing material shear friction to overheat.
Therefore,during the extrusion process,it is necessary to strengthen the inspection of whether the heating and cooling systems are working properly;The setting of extrusion temperature should be based on process requirements and screw speed;Reasonably control the heating time and regularly clean the extrusion system.
2.Poor plasticization of extruded material
As mentioned earlier in the temperature control requirements,the issue of plasticization was mentioned.Generally,poor plasticization is mainly manifested as:the extruded layer has a frog skin like appearance;The surface of the plastic is black,dull,and has small cracks;The extruded layer has obvious seam at the bonding point;The main reasons for this are:
1.The temperature control is too low,especially in the front part of the machine;
2.Other plastic particles with different properties mixed in insulation or sheath materials;
3)The screw rotates too quickly,causing the plastic to not fully plasticize;
4)Plastic itself has quality issues.
For the above reasons,attention should be paid to the rationality of extrusion temperature control;The quality and product name of the materials received should be confirmed;Cannot blindly pursue output and increase extrusion speed;Strengthen the storage of raw materials,especially in the plastic drying process;Reasonably match the mold to enhance extrusion pressure and screw reflux.
3.The cross-section of the extrusion layer has pores or bubbles,which are mainly caused by:
1.Excessive temperature control(especially in the feed section);
2.Plastic is damp and contains moisture;
3.Long term parking and incomplete removal of decomposed plastic;
4.High humidity in the natural environment;
5.There is water or high content of vaporized substances in the cable core.
For the above reasons,the temperature of each section of the screw should be reasonably controlled;Pre dry the materials used in advance;Strict process operation requirements,improving the ability to evaluate the degree of plastic plasticization;Pay attention to the production environment and material storage conditions.
4.The extrusion size is unqualified,mainly manifested as core deviation;The thickness or outer diameter of the sheath exceeds the tolerance;The main reasons for its formation are:unstable extrusion and traction speeds;
1)The outer diameter of the cable core changes too much;
2.Excessive extrusion temperature leads to a decrease in extrusion volume;
3.Excessive impurities inside the plastic block the filter screen,causing a decrease in plastic flow rate;
4.The tension of the winding line is unstable;
5.The selection of the mold core is too large(extrusion type)or the length of the mold core bearing area is too short and biased towards the core;
6.Inappropriate selection of mold spacing;
7.Uneven temperature of the extruder head;
8.The concentricity of the extrusion mold is not adjusted properly;
9.Excessive temperature at the feed inlet makes it difficult to feed and affects the material flow;
For the above reasons,it is necessary to regularly measure the outer diameter of the sheath and adjust it in a timely manner;Reasonably selecting and adjusting extrusion molds;Pay attention to the tension changes of the winding line and adjust them in a timely manner;The temperature control should be consistent with the specified requirements;
5.The main reasons for the unqualified bonding strength of the longitudinal wrapping tape are:
1.The extrusion temperature is too low;
2.Excessive filling and overflow of ointment;
3.The production line speed is too fast,causing the sheath to be rapidly cooled;
4.The temperature of the hot water tank is too low and close to the mold opening;
5.The stretching ratio of the matching mold is too small,or the matching mold is unreasonable,causing it to form loose bags
6.The melting point of the longitudinal band composite film is too high;
Based on the above reasons,attention should be paid to the requirements for mold configuration,and if necessary,adjustments should be made according to the cable core;Do not allow the sheath to be rapidly cooled to improve bonding ability;It is not advisable to excessively reduce the temperature of the machine head in order to improve the shaping ability of the sheath;Pay attention to the amount of ointment to be filled,so that a thin layer can be scraped off by lightly touching the cable core with your fingers.
6.The appearance of the extruded package is unqualified,mainly manifested by scratches on the surface of the extruded package layer;Rough with trachoma or microcracks;Any defects caused by insufficient plasticization.The main reasons are:
1.The selection of extrusion die sleeve is unreasonable.Too small causes Fried Dough Twists lines;Excessive size can cause detachment or compression looseness;
2.There are impurities stuck and scratched on the surface of the sheath in the extrusion mold sleeve.
3.Excessive heating temperature of the extruder head can cause roughness,or too low temperature can cause microcracks;
4.There is damage to the fixed diameter area of the mold sleeve;
5.The sheath is scratched inside the sink;For the above reasons,defects can be eliminated or prevented in production.In actual production,in addition to the above-mentioned defect phenomena and causes,there are also issues such as wiring problems,overlapping width of longitudinal packages,and bamboo shaped shapes.We should observe and summarize more in production,grasp the main and essence of the problem,and solve it easily,improving the quality level of cables.
Plastic scorching is a common quality defect in the plastic extrusion process,which is manifested as:excessively high temperature display;There is a lot of smoke and a strong irritating smell at the die mouth of the machine head,and in severe cases,there may be a popping sound;Extruded plastic layer with charred particles;There are continuous bubbles at the adhesive joint;The main reasons for the occurrence of annotations are:
1.Temperature control reaches the temperature of plastic thermal degradation at an ultra-high level;
2.The screw has not been cleaned for a long time,and the accumulated burnt material is squeezed out with the molten plastic;
3.Excessive heating or shutdown time can cause the plastic inside the barrel to decompose due to prolonged heating;
4.Loss of control or misalignment of temperature control instruments,resulting in high-temperature decomposition;
5.The cooling system of the extruder was not turned on,causing material shear friction to overheat.
Therefore,during the extrusion process,it is necessary to strengthen the inspection of whether the heating and cooling systems are working properly;The setting of extrusion temperature should be based on process requirements and screw speed;Reasonably control the heating time and regularly clean the extrusion system.
2.Poor plasticization of extruded material
As mentioned earlier in the temperature control requirements,the issue of plasticization was mentioned.Generally,poor plasticization is mainly manifested as:the extruded layer has a frog skin like appearance;The surface of the plastic is black,dull,and has small cracks;The extruded layer has obvious seam at the bonding point;The main reasons for this are:
1.The temperature control is too low,especially in the front part of the machine;
2.Other plastic particles with different properties mixed in insulation or sheath materials;
3)The screw rotates too quickly,causing the plastic to not fully plasticize;
4)Plastic itself has quality issues.
For the above reasons,attention should be paid to the rationality of extrusion temperature control;The quality and product name of the materials received should be confirmed;Cannot blindly pursue output and increase extrusion speed;Strengthen the storage of raw materials,especially in the plastic drying process;Reasonably match the mold to enhance extrusion pressure and screw reflux.
3.The cross-section of the extrusion layer has pores or bubbles,which are mainly caused by:
1.Excessive temperature control(especially in the feed section);
2.Plastic is damp and contains moisture;
3.Long term parking and incomplete removal of decomposed plastic;
4.High humidity in the natural environment;
5.There is water or high content of vaporized substances in the cable core.
For the above reasons,the temperature of each section of the screw should be reasonably controlled;Pre dry the materials used in advance;Strict process operation requirements,improving the ability to evaluate the degree of plastic plasticization;Pay attention to the production environment and material storage conditions.
4.The extrusion size is unqualified,mainly manifested as core deviation;The thickness or outer diameter of the sheath exceeds the tolerance;The main reasons for its formation are:unstable extrusion and traction speeds;
1)The outer diameter of the cable core changes too much;
2.Excessive extrusion temperature leads to a decrease in extrusion volume;
3.Excessive impurities inside the plastic block the filter screen,causing a decrease in plastic flow rate;
4.The tension of the winding line is unstable;
5.The selection of the mold core is too large(extrusion type)or the length of the mold core bearing area is too short and biased towards the core;
6.Inappropriate selection of mold spacing;
7.Uneven temperature of the extruder head;
8.The concentricity of the extrusion mold is not adjusted properly;
9.Excessive temperature at the feed inlet makes it difficult to feed and affects the material flow;
For the above reasons,it is necessary to regularly measure the outer diameter of the sheath and adjust it in a timely manner;Reasonably selecting and adjusting extrusion molds;Pay attention to the tension changes of the winding line and adjust them in a timely manner;The temperature control should be consistent with the specified requirements;
5.The main reasons for the unqualified bonding strength of the longitudinal wrapping tape are:
1.The extrusion temperature is too low;
2.Excessive filling and overflow of ointment;
3.The production line speed is too fast,causing the sheath to be rapidly cooled;
4.The temperature of the hot water tank is too low and close to the mold opening;
5.The stretching ratio of the matching mold is too small,or the matching mold is unreasonable,causing it to form loose bags
6.The melting point of the longitudinal band composite film is too high;
Based on the above reasons,attention should be paid to the requirements for mold configuration,and if necessary,adjustments should be made according to the cable core;Do not allow the sheath to be rapidly cooled to improve bonding ability;It is not advisable to excessively reduce the temperature of the machine head in order to improve the shaping ability of the sheath;Pay attention to the amount of ointment to be filled,so that a thin layer can be scraped off by lightly touching the cable core with your fingers.
6.The appearance of the extruded package is unqualified,mainly manifested by scratches on the surface of the extruded package layer;Rough with trachoma or microcracks;Any defects caused by insufficient plasticization.The main reasons are:
1.The selection of extrusion die sleeve is unreasonable.Too small causes Fried Dough Twists lines;Excessive size can cause detachment or compression looseness;
2.There are impurities stuck and scratched on the surface of the sheath in the extrusion mold sleeve.
3.Excessive heating temperature of the extruder head can cause roughness,or too low temperature can cause microcracks;
4.There is damage to the fixed diameter area of the mold sleeve;
5.The sheath is scratched inside the sink;For the above reasons,defects can be eliminated or prevented in production.In actual production,in addition to the above-mentioned defect phenomena and causes,there are also issues such as wiring problems,overlapping width of longitudinal packages,and bamboo shaped shapes.We should observe and summarize more in production,grasp the main and essence of the problem,and solve it easily,improving the quality level of cables.