1, Cause of mould:
The full inspection of pre production degreasing can effectively prevent the products with oil and rust stains and runner materials from being mixed into the comminuted materials and being used (especially in the production process rather than in the initial trial);
Too small or rough gates of the mold will produce a lot of friction heat. If the mold exhaust is poor, it will cause gas combustion to produce obvious black stripes (black spots).
2, Reason for the device:
·The dryer motor operates for a long time, containing dirt and dirt, and must be cleaned regularly;
·The filter screen of the dryer shall also be cleaned and replaced regularly, otherwise, foreign matters may enter or materials will change color and agglomerate due to poor ventilation;
·The dryer is not (completely) sealed due to the negligence of operators or insufficient operation equipment, which leads to the dust in the air; or the dust flies away, polluting the surrounding products and materials in the crusher; or the material cylinder is too large, which is not easy to operate, which ignores the corner (at the feed pipe and its interface) and other factors, leading to the incomplete cleaning of the material cylinder during the refueling process.
·During long-term production and operation, 5S and its protection are not well done normally, and dust falls on the equipment, resulting in mixing
·The shield of the crusher is not in place, resulting in pollution and other materials;
·The crusher shall be used in black and white as far as possible;
·If the nozzle aperture is too small or the inner surface is rough, there will be a lot of friction heat. If the mold exhaust is not good, it will cause gas combustion to produce obvious black stripes (black spots);
·When the gun barrel or rubber head is worn and cracked and bent, a part of the polymer will overheat and produce black stripes (black spots);
·When the rubber ring is worn, the molten rubber cannot move forward smoothly. The phenomenon of extruding will cause too much gas in the material pipe. When the injection is smooth, black lines will be produced due to sharp friction;
·If the tolerance between the outer diameter of the rubber passing ring and the clearance between the cylinder walls is too small, the screw melt will produce a large resistance surface, which will generate friction heat, resulting in black lines (it is possible to remove the outer diameter of the rubber passing ring and grind a few or replace a new product with a large tolerance, so that the screw melts smoothly);
·The screw and the material pipe are eccentric, resulting in very friction heat;
·When the screw compression ratio is too large, the shallow groove of the feed part will produce greater friction with the inner wall of the barrel and the raw materials, which will cause the raw materials to overheat and decompose and produce black stripes (black spots);
·The temperature is not correct, the error between the actual temperature of the electric heater and the thermometer is too large, and the temperature of a certain section is overheated, which is not easy to be intuitionistic, so it needs to be checked by a measuring device;
3, Material:
·The raw material itself has black spots, and the proportion of such black spots exceeds the allowable range of the customer's incoming inspection or the allowable standard of the finished product;
·The raw material bag is damaged or polluted during transportation, transportation and storage, and foreign matters are mixed in;
·The material is mixed with sundries in the manual proportioning or material making;
·Some raw materials need to be added with lubricant. If not enough lubricant is added, friction heat will be generated seriously. Because too much waste gas is not removed in time, black marks (black spots) will be generated due to gas combustion;
·The heat resistance of the raw material itself is insufficient, and the raw material (additive) can't bear the operating temperature;
·The material bag or storage material bag is unclean, and foreign matters are mixed when it is used again;
4, Other reasons:
·Different materials are produced in the barrel for a long time. Due to the change of temperature, the oxidation and degradation produced are different from the adhesion of various materials to the metal surface and other related factors. As a result, the carbonization layer is gradually formed on the screw surface, pipe wall, nozzle and other places, and is separated and gradually brought out when meeting the materials with high viscosity, If there are scars or notches on the screw and pipe wall, the molten material will be more easily detained. If the machine is stopped frequently, the above problems will be more serious;
·Those who don't understand the material smash the defective products, resulting in material confusion;
·The technician shall confirm whether the defective products are smashed or discarded;
·When replacing materials, it is convenient to operate as a picture, only use the air gun to blow away the residual material scraps, but this method can not thoroughly clean the material barrel; or use the air gun to blast at the scene, resulting in the dust diffuse in the whole workshop;
·The floor products or runner materials are directly put into the crusher;
·The defective products are easily smashed with a few blows of the air gun;
·When processing the products in the red box, directly pour them into the pulverizer;
·When dealing with foreign matters, only one reason is found, and all the real reasons are found;
·The pulverizer has the phenomenon of blade scraping, without timely adjustment and control of materials;
·Shutdown methods for special materials such as PP, PMMA and ABS;
·The feeding method is wrong. If the black material is added and the white material is added directly, the black chips may fall into the white material due to static electricity or other reasons;
·When washing the machine, the low-temperature materials used in the discharge pipe are not completely replaced. When the operating temperature rises,
As a result, the low-temperature materials (fire retardant, additive, etc.) can not bear this temperature and are degraded by heat
This usually occurs at the nozzle (especially during production rather than during initial trial).
