• The Importance of Uniform Wall Thickness in Plastic Part Design

    Want to know how to optimize your plastic part design for manufacturing with uniform wall thickness?   Wall thickness is one of the most important rules of injection molding part design that you should treat it as an essential part of your overall part design This is especially important as wall thickness is considered as one of the most importnat factors that determin the success or failure of the plastic product. In this article we will explore  the importance of maintaining uniform wall thickness to get your project going successfully Why maintain uniform wall thickness?   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. Why do we attach so much attention…

    Mold design August 22, 2021
  • Tooling Design Two-stage ejection Mechanism

    What is double ejection? Some complex plastic parts often have undercuts that are too deep to be ejected directly by neither lifters nor slides.  After ejection, the molding parts may still rest on top of the ejector pins,so another stage of ejection is needed to clear the parts. This typical solution is called double ejection system which  s can be a mechanical system driven or supplemented by air or hydraulics.   Second ejection mechanism: Add an extra set of ejector plate. The first set of ejector plate that is attached to the A plate(referred as Ejector Assembly A) is to complete the first stage of ejection while the ejector plate attached to B plate (referred as Ejector Assembly B)  is to complete the second stage of ejection as shown in Figure1. Figure 1 Add series of springs or nylon plugs to make sure that both ejector assembly A and B are attached…

    Mold design June 23, 2021
  • Mold design-How to choice the Gate location

     Basic function of gate   The gate is the bridge of runner and the cavity, and also the last stage of injection system of injection mold.   1) Enforce the molten plastic from the runner to enter each cavity at the fastest speed.   2)Once the cavity is fully filled, the gate can be quickly cooled and sealed to prevent the uncooled plastic in the cavity from returning.     How to design gate   There are no set rules to flollow on how to design the injection gate. It is done mostly based on experience, but there are two basic elements that must be considered:   The larger the cross-sectional area of the gate, the better, and the shorter the length of the gate, the better to reduce the pressure loss when the molten plastic passes through.   The gate must be narrow in order tomake the gate cool down easilyand…

    Mold design October 10, 2020
  • Vacuum cleaner elbow mould design—-complex mold design

    This is a set of high precision plastic mould for Portable Vacuum Cleaner  It is Vacuum Inlet Elbow. This type of plastic tooling is usually structured with oil cylinder core pulling or arc core pulling, which is a typical structure of automotive vacuum cleaner molds. The product has 3 undercuts. This is how we solve the undercut:The undercut 1 and undercut 2 use cylinder core pulling , and undercut 3 uses Angular pin  + spring core pulling.   The mold injection system adopts nozzle, cold runner and edge gate, 1*2   The undercut 1 adopts a built-in slide structure, and dovetail groove is used to guide the silde and retract from the undercut.   Mold ejection   Mold cooling     Mold overall structure   CAV We are a mold company based in that manufacturing Custom Molded Prototypes and Production Parts with Fast Lead Times

    Mold design October 8, 2020
  • Gate Design-HS Plastic Mold Shop

    What proper gate design is important? The gate serves as the entrance to the mould cavity and should be designed to permit the injection mold to fill easily. It is very important to follow below gate considerations while picking gate location at the early stage of plastic mould design. Gates should not be placed where part-bonding or impact will take place in use. The gate area will usually have higher residual stresses than the rest of the part due to the packing that takes place. Therefore, it will be weaker than the rest of the part. Position the gate to minimize trimming problems. Scissor-type gate cutters, kept sharp, will work smoothly and leave no “blemish” marks. If possible, gate into the thickest section to avoid incomplete fill or sink marks. This will also minimize flow marks and distortion associated with setting into a thick section from a thin one. Position the gate so that venting…

    Mold design February 8, 2020
  • 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
  • Cold Slug Well in Plastic Mold Design

    Cold slug well is a very imporant part of plastic mold design. It is  defined as the small nub of plastic that cools and solidifies inside the nozzle tip during the cooling cooling phase of the injection cycle. It is designed to store cold slug  caused intermittently by the nozzle due to heat loss and low temperature. Cold slugs could clog or slow down the material flow in runner and cavity and cause cold scars or cold marks on plastic part. The cold slug well is usually placed at the end of primary runner. When the branch runner is too long, cold slug well should be designed as well to store the front plastic cooled by mold. Cold slug well is a very imporant part of gate system and it should not be neglected at mold design.   For molded plastic part made from flame-retardant PC, the design of cold well determines the the quality of…

    Mold design January 23, 2020
  • Two shot injection mold design consideration

    This article discusses basic consideration for designing two-shot injection molds, which is referred to also as dual-shot, dual-injection, double-shot, double-injection, multi-shot, 2k molding, and overmolding Before tool design, one should check machine injection unit Injection unit sometimes constrain the tooling type. Material shrinkages for each material should be considered. Shrinkage may cause warpage and flash if those are not made up properly in tooling phase. If there is big different in melt temperature between materials, toolheat balancing should be .studied Tooling should consider gate location, access, allowable gate vestige. Draft angle in 2K molding is very critical factor which deciding wheremolded part stuck and rotating. In 1st shot molding, molded part should be stuck on rotating core and 2nd shot molding, molded part should remain on the side of ejecting system employed.   If part design imposing creating shut-off surface with molded part after rotating,Draft angle on shut-off surface should be…

    Mold design January 13, 2020
  • Part design guidelines on double injection molding

    In this article, we will show you from three aspects to be taken into consideration when designing plastic parts for double injection molding so we can save our customers time and money in the long run.   Mechanical structure     Surface Contact Adhesion is depending on materials compatibility, process temperatures, surface contact area, molding sequence and designing of mechanical interlock systems. If design not allows enough contact surface area, Tooling can make up like Make-up 1 : Increase expose surface byincreasingroughness. Make-up 2 : Employ interlock Wall Thickness Utilize 2nd shot to get more uniform wallthickness  Reinforce the 1st  and 2nd shot(transparent) by structure design such as “H” section etc. Thin but high rib in 2nd short. First shot thicker than 2nd shot. 2nd shot should be as thin as possiblewhen flow and weld line is not a issue. In MP case, 1st shot 0.6mm, 2nd shot 0.6mm was made Avoid sharpcorner Make…

    Mold design January 10, 2020


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