The most detailed injection mold adjustment process. 2of 2
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The most detailed injection mold adjustment process.
The time required to complete an injection molding process is called the molding cycle, also called the molding cycle. It actually includes the following parts
Molding cycle: The molding cycle directly affects labor productivity and equipment utilization. Therefore, in the production process, the relevant time in the molding cycle should be shortened as much as possible under the premise of ensuring the quality. Injection time and cooling time are of the utmost importance throughout the molding cycle and they have a decisive influence on the quality of the product. The filling time in the injection time is directly inversely proportional to the filling rate, and the filling time in production is generally about 3-5 seconds.
The holding time in the injection time is the pressure time of the plastic in the cavity, which accounts for a large proportion in the whole injection time, generally about 20-120 seconds (the extra-thick parts can be as high as 5-10 minutes). Before the melting of the melt at the gate, the amount of dwell time has an effect on the dimensional accuracy of the product. If it is later, it has no effect. The holding time also has the best value, which is known to depend on the material temperature, the mold temperature and the size of the main runners and gates. If the size and process conditions of the main runners and gates are normal, it is usually the value of the pressure at which the range of fluctuation of the shrinkage of the product is the smallest. The cooling time is mainly determined by the thickness of the product, the thermal properties and crystallization properties of the plastic, and the temperature of the mold. The end point of the cooling time should be based on the principle of ensuring that the product does not cause changes during demolding. The cooling time is generally between 30 and 120 seconds. The cooling time is not necessary, which not only reduces the production efficiency, but also complicates the complicated parts. It is difficult to release the mold, and even the mold release stress is generated when the mold is released. Other times in the molding cycle are related to whether the production process is continuous and automated, as well as the degree of continuity and automation.
The general injection molding machine can be adjusted according to the following procedures.
Adjust the barrel temperature to the middle of the range and adjust the mold temperature based on the temperature range provided by the material supplier's data.
Estimate the amount of glue required to adjust the injection molding machine to two-thirds of the estimated maximum shot size. Adjust the backstrip (pumping) stroke. Estimate and adjust the secondary injection time and adjust the secondary injection pressure to zero.
Initially adjust the first-stage injection pressure to half (50%) of the limit of the injection molding machine; adjust the injection speed to the highest. Estimate and adjust the cooling time required. Adjust the back pressure to 3.5 bar. The degraded resin in the cartridge is removed. Use semi-automatic injection molding mode; start the injection molding process and observe the action of the screw.
The injection speed and pressure can be appropriately adjusted as needed, and if the filling time is shortened, the injection pressure can be increased. As mentioned earlier, the final pressure of the filling can be adjusted to 100% of the primary injection pressure due to a process before the full filling. The pressure must eventually be adjusted high enough so that the maximum speed that can be achieved is not limited by the set pressure. If there is a flash, you can reduce the speed.
After each observation period, the amount of glue and the switching point are adjusted. The setting procedure is such that it is possible to obtain a 95-98% filling of the shot weight in the first stage of injection molding.
When the injection volume, switching point, injection speed and pressure of the first-stage injection molding are properly adjusted, the second-stage pressure maintaining pressure adjustment procedure can be performed.
Adjust the holding pressure as needed, but do not overfill the cavity.
The screw speed is adjusted to ensure that the melt is completed just before the cycle is completed and the injection cycle is not limited.
Reduce cycle time to increase productivity
For most injection molders, the injection cycle can directly affect two main purposes:
1. Get more parts from the machine every day;
2. The parts meet the requirements of the guests.