Summary: Plastics are indispensable tool materials for human production and life. Injection molding is a process of shaping plastic by melting it and injecting it into a predesigned mold, then obtaining a molded product by curing after the temperature drops. Injection molding is done by means of molds and injection molding machines. It is usually used for mass production of complex parts and is an important processing method. The new injection molds have to confirm a lot of contents, such as mold steel material, mold size, mold movement structure, etc. This article mainly introduces the contents of the mold confirmation and the main purpose of each step from the perspective of the product.
Key words: Injection molding, process flow, runner balance, gate freezing
1 mold dry running
After the mold is installed on the matching machine, it needs to run empty to verify whether the mechanical action of the mold is normal and without abnormal noise. The contents of the inspection include (1) whether the mold positioning ring and the nozzle of the injection molding machine are normal and seamless. (2) cooling system inspection, whether the flow rate of each water channel of the mold meets the design requirements, and the water flow and the water pressure of the parallel water channel are consistent. (3) Whether the transmission parts of the thread structure mold are installed normally, and can rotate in the direction of thread. (4) pin-point gate mold to check whether the action of the runner stripper can open normally. (5) Whether the mold guide pillar and the positioning block is normally closed, and there is scratched or worn on guide pillar and positioning block after open the mold. (6) Whether the core pulling device/ejector system is in normal operation, no jamming or abnormal noise. (7) There is no damage on the surface of the cavity. (8) After the auxiliary system hydraulic cylinder/limit switch is in position, the signal can be fed back to the mold or the injection machine; the hot runner system can be heated according to the setting temperature; the auxiliary blowing system: whether the air valve at gate position of the valve needle mold can normally control valve needle opening, and the mold assisting the blowing during ejection can normally blow when it is ejected. The further test can only be carried out after the result of the empty running of the mold is passed, otherwise it is necessary to adjust the mold or machine and then test again.
2. Stability test
By adjusting the injection speed, holding pressure, cooling time and other parameters, to explore the range of process parameters, and evaluate the product and mold, such as: whether the product has flashing, strain, shrinkage, bubbles, burn, etc. Whether the mold steps are normal, there is water leakage or exhaust problem, etc. If there is any problem, the mold adjustment is required and the stability test should be performed again.
3. Gauge repeatability and repeatability test
The purpose of this test is to evaluate the repeatability of the gauge and the same size measured by different persons. Only the repeatability of the gauge and the R&R result of the personnel repeatability are less than 20%, can the accuracy of the subsequent measurement data be assured.
If the R&R test result is greater than 20%, it is necessary to check whether it is caused by gauge or persons. If it is the gauge, it needs to be calibrated and then re-measure; if it is a person, it needs to be re-trained and then re-measure.
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