2. The temperature control is inaccurate, and the temperature at the rear end of the barrel is too high. Adjust the temperature setting and check whether the cooling water channel is blocked.
3. The screw is covered with glue-plastic covers the screw and rotates together.
4. Too much oil was added to the plastic, which caused the screw to slip.
5. There are too many recyclable materials added to the plastic.
6. The wear of screw and barrel, as well as the wear of apron, may cause the screw of injection molding machine to be unable to feed, resulting in plastic leakage and unable to transport to the front end of barrel.
7. If the plastic particles are too large, bridging will occur. Just crush the plastic.
8. If the new screw does not discharge, it may be that the design of the barrel and discharge port of the screw is inappropriate. For the screw, the spiral groove in the feed section of the screw is too shallow, which leads to the screw being unable to drive the plastic to be transported forward when rotating. It may also be that the amount of materials transported is very small, and the barrel is designed as a discharge port.
Extended data:
principle of operation
The working principle of injection molding machine is similar to that of injector. It is a process of injecting molten plasticized plastic (that is, viscous fluid state) into a closed mold cavity with the help of the thrust of a screw (or plunger), and curing to obtain a product.
Injection molding is a cyclic process, and each cycle mainly includes: quantitative feeding-melt plasticization-pressure injection molding-mold filling and cooling-mold opening and taking parts. Take out the plastic part, and then close the mold for the next cycle.
Operation items of injection molding machine: Operation items of injection molding machine include control keyboard operation, electric control system operation and hydraulic system operation. Selection of injection process action, feeding action, injection pressure, injection speed and ejection type, monitoring of temperature in each section of the barrel, adjustment of injection pressure and back pressure, etc.
The molding process of screw injection molding machine is generally as follows: firstly, granular or powdery plastic is added into the barrel, and the plastic becomes molten through the rotation of the screw and the heating of the outer wall of the barrel, then the machine closes the mold, the injection seat moves forward, so that the nozzle sticks to the gate of the mold, and then pressurized oil is introduced into the injection barrel to push the screw forward.
Therefore, the molten material is injected into the closed mold with a relatively low temperature at a relatively high pressure and speed, and the product can be taken out after opening the mold after a certain period of time and cooling under pressure maintaining (also called pressure maintaining) (the purpose of pressure maintaining is to prevent the molten material from flowing back in the mold cavity, replenish the material in the mold cavity, and ensure that the product has a certain density and dimensional tolerance).
The basic requirements of injection molding are plasticization, injection and molding. Plasticization is the premise of realizing and ensuring the quality of molded products, and in order to meet the requirements of molding, injection must ensure sufficient pressure and speed.
At the same time, due to the high injection pressure, a relatively high pressure is generated in the mold cavity (the average pressure in the mold cavity is generally between 20 and 45 MPa), so there must be enough clamping force. It can be seen that injection device and clamping device are the key components of injection molding machine.
There are three main aspects in the evaluation of plastic products. The first is the appearance quality, including integrity and color. Second, the accuracy between size and relative position; The third is the physical properties, chemical properties and electrical properties corresponding to the use. These quality requirements have different scales according to the application of products.
The defects of the product mainly lie in the design, manufacturing accuracy and wear degree of the mold. But in fact, technicians in plastic processing plants often encounter such a dilemma: using technical means to make up for the problems caused by mold defects has little effect.
Process adjustment in production process is a necessary way to improve product quality and output. Because the injection cycle itself is very short, if the process conditions are not well mastered, waste products will emerge one after another. When adjusting the process, it is best to change only one condition at a time and observe it several times.
If the pressure, temperature and time are all adjusted together, it is easy to cause confusion and misunderstanding, and I don't know why there is a problem. There are many measures and means to adjust the process.
In addition, we should pay attention to the dialectical relationship in solving problems. For example, if the product is sunken, sometimes the material temperature should be increased and sometimes the material temperature should be lowered; Sometimes it is necessary to increase the quantity of materials, and sometimes it is necessary to reduce the quantity of materials. It is necessary to realize the feasibility of using reverse measures to solve the problem.
Baidu encyclopedia-injection molding machine