Improve Injection Molding Part Weight Stability with Plastrol

Improve Injection Molding Part Weight Stability with Plastrol

With so many variables in play during the injection molding process it can be complex and oftentimes tasks fall through the cracks, no matter how obvious. One of the most common is part weight variations which can occur due to inconsistent check ring response. When stabilized this can greatly improve shot-to-shot repeatability. Luckily, with the right machinery and technology in use, preventative measures can be taken and the process optimized.

Shibaura Machine’s V70 controller includes the Plastrol function which offers the user control of the screw’s operation after charging completes. Utilizing one of four operation types, or combining them together, the user can stabilize the shot size and optimize the check ring response of the screw tip. Being able to ensure part weight and filling pressure is stable can be a game changer for repeatability, especially when molding critical parts.


Understanding Plastrol Operation Types

Using one or a combination of the Plastrol operations mentioned below, the user can ensure better shot weight repeatability and consistency in part production.


By injecting resin at a lower pressure after charging it will allow the auxiliary compression of the resin and better regulate its density. Decompression begins from the position where the PRE-INJECTION AFTER CHARGE is completed and the injection speed shift and final packing control positions are automatically corrected. This process improves stabilization of the shot size.


This operation allows for advancing of the screw after decompression and will close the check ring to stabilize it.


This function reverses the screw operation before starting injection. It will lower the resin pressure between the check ring and spacer, also speeding up check ring response and stabilizing it.


This operation will reverse the screw after decompression is complete and close the check ring for stabilization.

EPF Plastic has a deep knowledge of injection moulding and is a reliable and competent partner both in choosing your full-Electric solution and in providing after-sales assistance. Do you want to know more about this topic or would you like more information about the Plastrol function of Shibaura Machine? Visit the dedicated page, or contact us at