• Why Wall Thickness is important for a defect-free plastic?

    Metal parts are often designed with thick walls, while plastic products should ideally maintain uniform wall thickness for uniform flow and less shrinkage as illustrated as below. For plastic parts, a gradual change in wall thickness or uniform wall thickness is recommended to reduce stress concentration and other potential issues. In this article we’ll explore what you need to know about the importance of maintaining proper wall thickness in Injection Moulding manufacturing process Maintain a wall thickness of less than 5mm because thick walls can lead to long cycle times and poor mechanical properties. Avoid large variations in wall thicknesses in order to simplify flow pattern and minimize variations in shrinkage that can lead to warpage. Avoid abrupt changes in wall thickness, as this can create stress concentration areas that may reduce a part’s impact strength. Wall thickness changes should have transition zones that reduce the possibility of stress concentrations, sinks, voids, and…

    Mold design August 22, 2021
  • 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
  • How to solve silver streaks in injection molidng

    Silver streaks are a very common phenomenon appearing on the surface of plastic injection molded products. They are shining line shaped patterns usually caused by moisture, but can also be caused by high filling rates and poor vents which can cause entrapping of gas either from the environment, mold water leaks, etc. These can be considered external appearance quality defects in exterior parts of consumer electrical products, automobiles, motorcycles, etc. The most commonly seen streaks are shown as below. Moisture streaks/splay marks Burning streaks/silver streaks   Dark streaks Color streaks     The cause for the formation of streaks can be deter-mined in many defective injection products only after costly investigations,especially as the appearance of burning and moisture streaks is similar.Extensive knowledge of the plastic,the mold design and the plastic injection molding processing are indispensable for overcoming the problem.Before launching expen-sive and time-consuming investigations the following points should be checked in the sequence given and if…

    Injection molding process January 17, 2020
  • How to define number of cavities in a plastic injection mold?

    When it comes to cavity number for a plastic injection mold, there is a lot to be considered by injection molder though usually the number of cavities is decided by the customer.  Please note the following:   The most important thing to consider is the size of the part and how complext. Does the part have a lot of slides,lifters, core pulls etc. Size of press that the mold is going to run in, how many tons in the press rated for, what’s the platen size, and what’s the shot size. What is total quantity of the part? all you must consider delivery time on the parts. If you have a tight just in time delivery schedule that will also determine the amount of cavities needed to support the timing. What is the target cycle time? How is the resin going to be distributed within the mold? surface runner, insulated…

    Mold making January 7, 2020
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