Pressure instability is a common issue encountered during the operation of vertical injection molding machines. For instance, an injection mold may initially fill completely, but after producing several molds, dissatisfaction may arise. Occasionally, the machine may produce empty molds. If operations continue under these conditions, problems may arise, or one might notice that the quality fluctuates after a certain period of continuous operation. Could these issues be linked to pressure instability?
Here are some key considerations to evaluate this situation:
Occasional spillage from the nozzle can occur. This might happen when the guide is blocked or when the nozzle head is too rigid, preventing proper material ejection, resulting in empty molds. However, if the lower mold functions correctly, it might be because any previous overflow has melted due to time constraints. If the earlier mold cycle wasn’t completed, it’s possible that the subsequent mold has an excessive amount of material, which can lead to high pressure. Additionally, if pressure increases, it may prevent spillage while simultaneously causing excessive pressure.
To address this, consider increasing the loosening mechanism. If the loosening is sufficiently large, it’s essential to verify whether the junction between the material flow path and the nozzle is appropriately designed; often, using a pad or paper treatment can help.
Furthermore, raising the temperature of the nozzle and the material flow path in the vertical injection molding machine can be beneficial.
It’s also important to adjust the injection position and pressure settings to achieve a short range with high pressure.
Finally, be mindful that excessive holding pressure or prolonged injection time can also contribute to pressure instability, as well as other factors affecting pressure and flow dynamics.