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Ejection Systems in Injection Molds

    The ejection of plastic products is the last step in the plastic injection molding process. When the mold is opened, the plastic product must be held on the mold half (usually the core) by an ejector mechanism for releasing the plastic product. That is to say, the quality of the ejection determines the quality of the plastic product. Commonly used ejector mechanism ejector pin, ejector sleeve, stripping plate, ejector block

    When the ejector pin is designed, in order to prevent the plastic product from being deformed during ejection, the ejection force must be distributed as evenly as possible and as close as possible to the core or the part that is difficult to eject. For example, the slender column of the plastic product is Ejected with an ejector sleeve.

    The ejection force should be applied to the most rigid and strong part of the plastic product (avoid acting on thin sections), and the movable surface should also be as large as possible, such as protruding flanges, ribs, and walls of the shell, etc. Most barrel products are released using the top plate. At the same time, in order to prevent the ejection marks from affecting the appearance of plastic products, the ejection position should be set on the hidden surface or non-appearance surface of plastic products; for transparent plastic products, special attention should be paid to the selection of ejection position and ejection form.

    In addition, to avoid the ejection marks and deformation of plastic products caused by vacuum adsorption, a combined ejection method or ventilation with porous steel can be used. For example, the ejector pin is combined with the top plate, or the ejector pin is combined with the ejector block. The thimble gap should be appropriately increased for ventilation, and an air intake valve should be used if necessary. In addition, the ejector mechanism should be reliable and flexible, with sufficient strength and wear resistance


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