operation 3.1 operation procedure of injection molding machine Mold closing → premolding → reverse shrinkage → nozzle advance → injection → pressure maintaining → nozzle receding → cooling → mold opening → ejection → door opening → workpiece taking → door closing → mold closing. 3.2 operation items of injection molding machine The operation of injection molding machine includes keyboard operation, electrical control cabinet operation and hydraulic system operation. 

Selection of injection process, feeding action, injection pressure, injection speed and ejection form, monitoring of temperature, current and voltage in each section of the cylinder, and adjustment of injection pressure and back pressure, etc. 3.2.1 selection of infusion action General injection molding machine can be manual operation, can also be semi-automatic and fully automatic operation.   Manual operation is in a production cycle, each action is achieved by the operator to flip the operation switch. General in the trial mold only choose.   

When semi-automatic operation, the machine can automatically complete a work cycle of action, but after each production cycle the operator must open the safety door, take down the workpiece, and then close the safety door, the machine can continue the next cycle of production.   When fully automatic operation, the injection molding machine can automatically enter the next working cycle after completing the action of one working cycle.

 In the normal continuous work process without stopping for control and adjustment. But must pay attention to, if the need for full automatic work.

(1) do not open the safety door midway, otherwise full automatic operation interruption; 

(2) timely feeding; 

(3) if choose electric eye induction, should pay attention not to close the electric eye.   In fact, in the full - automatic operation is usually also needed to temporarily stop, such as to the machine mold injection release agent.   Normal production, generally choose semi - automatic or automatic operation. At the beginning of operation, the operation mode (manual, semi-automatic or fully automatic) shall be selected according to the production needs, and the manual, semi-automatic or fully automatic switch shall be adjusted accordingly.   

Semi-automatic and full automatic working procedure has been determined by the line itself, the operator only needs to change the size of speed and pressure on the electric cabinet, the length of time, the number of thimble and so on, will not be because the operator adjusts the wrong button and make the working procedure chaos.   When each action in a cycle is not adjusted properly before, should first choose manual operation, after confirming that each action is normal, then choose semi-automatic or fully automatic operation. 

3.2.2 pre-shaping action selection The injection molding machine is generally provided with three options according to whether the injection seat is receding before and after preloading, that is, whether the nozzle leaves the mold.   

(1) fixed feeding: the nozzle before and after premolding is always attached to the mold, and the filling seat is not moved.   

(2) pre-feeding: the nozzle carries out premolding feeding against the mold. After the premolding is completed, the filling seat receded and the nozzle left the mold. The purpose of choosing this way is: when premolding, the injection hole of the mold is used to press against the nozzle, so as to avoid the discharge of molten material from the nozzle when the back pressure is high. After premolding, the nozzle and the mold can be avoided to contact for a long time and generate heat transfer, affecting the relative stability of their respective temperatures.   

(3) after feeding: after the injection is completed, the injection seat receded, the nozzle left the mold and then pre-molded, and the pre-molded injection seat moved forward. This action is suitable for processing plastic with narrow molding temperature. Due to the short contact time between the nozzle and the mold, the loss of heat is avoided, and the solidification of molten material in the nozzle hole is also avoided.   

After the injection is completed and the cooling timer is completed, the pre-molding action begins. The screw rotates to squeeze the plastic melt in front of the screw head. As a result of the screw front one-way valve, the molten plastic stored in the front end of the barrel, the screw back force. When the screw retreats to a predetermined position (which is determined by the travel switch to control the distance of screw retreats to achieve quantitative feeding), the premolding stops and the screw stops rotating. Followed by the reverse contraction action, that is, the screw do trace axial receding, this action can make the pressure of the molten material gathered in the nozzle can be removed, to overcome the "salivation" phenomenon caused by the imbalance of pressure inside and outside the barrel. 

If no retracement is required, the retracement should be stopped and the switch adjusted to the appropriate position to allow the premolding to stop. At the same time that the switch is pressed, the reverse stop switch is also pressed. When the screw retracted backward to press the stop switch, the retraction stopped. Then the seat began to recede. When the seat recedes to the stop switch, the seat stops receding. If the use of fixed feeding, should pay attention to adjust the position of the trip switch.   Generally, fixed feeding is adopted in production to save the advance and retreat operation time of filling seat and accelerate the production cycle.