The applied pressure (converted from oil circuit pressure) shall prevail. The role of injection pressure in injection molding is to overcome the flow resistance of plastic from the barrel to the cavity, give the rate of mold filling of molten material and compact the molten material.

Forming cycle

The time required to complete an injection molding process is called the molding cycle, also known as the molding cycle. It actually includes the following parts: molding cycle: 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 far as possible under the premise of ensuring quality. In the whole molding cycle, the injection time and cooling time are the most important, which have a decisive impact on the quality of products. The mold filling time in the injection time is directly inversely proportional to the mold filling rate. The mold filling time in production is generally about 3-5 seconds. The pressure holding time in the injection time is the pressure time for the plastic in the mold cavity, which accounts for a large proportion of the whole injection time, generally about 20-120 seconds (the extremely thick parts can be as high as 5-10 minutes). Before the melting material at the gate is frozen, the holding time has an impact on the dimensional accuracy of the product. If it is later, it has no impact. The holding time also has the most favorable value, which is known to depend on the material temperature, mold temperature and the size of the main runner and gate. If the size and process conditions of the sprue and gate are normal, the pressure value with the minimum fluctuation range of the shrinkage of the product is usually taken as the criterion. The cooling time mainly depends on the thickness of the product, the thermal and crystalline properties of the plastic, and the mold temperature. The end of the cooling time should be based on the principle of ensuring that the product will not change during demoulding. The cooling time is generally between 30 and 120 seconds. Too long cooling time is unnecessary, which will not only reduce the production efficiency, but also cause demoulding difficulties for complex parts, and even cause demoulding stress when forced demoulding. The other time in the forming cycle is related to the continuity and automation of the production process and the degree of continuity and automation.