• How can you make mold slide comes out of lifter?

    It is rare to see the structure of slide coming out of lifter in plastic injection molds. We are not experts, but we just design a typical mechanism that works quite well based on our experience.  Hope that it helps you. Mold Design Concept If we use common mold slide, the steel circled in red get stuck. And the undercut could not be released with this. How to design lifter head?   Green block is lifter with a prominent tail while the purple block is slide which is to release undercut and drive lifter to release undercut downwards. Further explanation on slide out of lifter in plastic injection mold Mold lifter needs a limit screw to limit the stroke of lifter travelling down while the spring is to prevent lifter from moving right with slide The science of structure of slide from lifter   Angel lifter drive slide to move right And…

    Mold design February 6, 2020
  • Techniques on plastic mold runner design

    This article talks about  some basic rules for runner design of plastic toolings, which, if you follow, will help you succeed with an injection mold design.  To provide part-to-part uniformity in a multicavity mold, the runner system should enable each cavity to fill at the same rate. Designing runners involves several compromises: The runner system should be compact to minimize the amount of rework. The runners must deliver melt that has retained maximum heat to completely pack out the cavity. At the same time, runners must cool quickly after delivering the melt to aid ejection. If the flow distances from the sprue to the various cavities are equal, the runner system is balanced. Since balanced runner systems contribute to melt uniformity among cavities, dimensional tolerances are easier to maintain. Unbalanced systems can cause cavity to cavity variations. (Figure 1) Figure 1 Occasionally, balancing the runner system and minimizing runner length conflict. In most cases it is better to accept the additional rework and use a more balanced system. Increased injection…

    Mold design February 1, 2020