The molding cycle time of the plastic injection mold
Contents
1. The beginning of the molding cycle
2. Residence time of molding cycle
The important thing to remember is that when considering the molding cycle time of the plastic injection mold, once the conditions are set to the machine's control instrument, the same cycle will be accurately repeated during production runs until some effective changes are made.
The beginning of the molding cycle
During the molding cycle time of the plastic injection mold, the action is initiated by closing the safety door in the mold area. When it is closed, the door will trigger two safety limit switches, one for the machine hydraulic system and the other for the entire electrical system. Since then, machine operation has been automatic. Assuming that the machine is equipped with a hydraulic clamp, the oil enters the jack installed in the main plunger to make the movable platen move forward at high speed under low pressure. Just before the mold half touches, the limit switch trips, causing oil to transfer from the jack to the main cylinder. The platen speed drops immediately, but the pressure increases. When the mold halves touch, the initial pressure of the cooling effect of the plastic injection mold will increase. The pressure switch will detect the pressure and set according to the cooling time requirements of the plastic injection mold. The switch will send a signal to the injection unit to start its cycle.
Residence time of molding cycle
At this point, the reciprocating screw is in the retracted position after the previous plasticization. After receiving the signal from the pressure switch, the shut-off valve opens and the hydraulic system of the fuel injector starts. This causes the screw to advance as a plunger and inject at pressures up to 20,000 psi. The high initial pressure used to counteract the cooling effect of the plastic injection mold is controlled by an adjustable safety valve or other flow control device. The length of the screw stroke, and therefore the injection volume, is also variable and controlled by a timer. When the cavity is filled, the signal from this timer to the injection speed controller will reduce the pressure on the screw, allowing the injection to continue at a reduced speed. The purpose of maintaining melt pressure is to minimize the possibility of heat sinks due to shrinkage during part cooling. In the molding cycle time of the plastic injection mold, the cooling time requirements of the plastic injection mold in this stage is called the residence time.
End of the molding cycle
At the end of the residence time, the timer sends a signal to the shut-off valve to close, and the screw resumes rotation. The plasticized melt advances to the front of the screw again, forcing it to compress back against the back until it touches the injection control limit switch. At this time, the clamp is still closed, and the cooling effect of the plastic injection mold is ongoing. According to the signal sent by the timer, set according to the cooling time requirements of the plastic injection mold, and the clamp slowly opens under pressure. Slow movement is necessary to protect the molded part, and continues until the quick return limit switch is contacted, at which time the platen speed increases. The rapid retraction continues until the control lever driven by the pressure plate touches another limit switch to reduce the speed and make the molded parts eject slowly and smoothly, and these parts fall into the box, water tank or conveyor belt. This completes the machine cycle and its attached injection unit cycle. During the molding cycle time of the plastic injection mold, the automatic operation of the injection machine is interrupted by the manual removal of parts that may be damaged by the automatic ejection.
In conclusion
The molding cycle time of the plastic injection mold can be described as the total time required to produce a complete shot of one or more parts, depending on the number of cavities in a given mold. The molding cycle is not only the time the material stays in the mold, but also the time required for mold closing and closing, any safety or delay time required at the beginning of the cycle, and injection time (the time required to fill the mold). The residence time required for the cooling effect of the cavity, the plastic injection mold or the cooling time requirements of the plastic injection mold, and the ejection time. Most plastic injection mold suppliers call the sum of these elements gate-to-gate time or total cycle time.
Taizhou Pubo Plastic Injection Mold Co., Ltd. has been committed to the development, research and industrial application of plastic injection molds and plastic preform products for many years. It is a top-level design expert in the domestic blow molding industry. If you want to learn more about the molding cycle time of plastic injection molds, please continue to pay attention to the official website of Taizhou Pubo. We will update related products from time to time and provide related product information and materials. We look forward to your visit and consultation.
Tags: the molding cycle time of the plastic injection mold, the cooling time requirements of the plastic injection mold, the cooling effect of the plastic injection mold
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