Molds used in injection molding have various structures and are selected according to the shape and material of the resin molded product to be made. In this issue, we will introduce the structure of a 2-plate mold, which can be called the basic form of a mold, as well as the names and roles of the parts used in the mold.
First, in a 2-plate mold, resin is poured inside two plates, the cavity (fixed side) and the core (movable side), for molding. The sprue, runner, and gate for pouring the resin are integrated with the molded resin product.
The structure of a 2-plate mold is shown above.
Names and roles of each component
Sprue Bush: The first path for the resin coming out of the molding machine. The nozzle of the molding machine repeatedly touches it and wears it out, so it is not carved directly into the mold and can be replaced.
Locating ring: Locates the center of the mold and the center of the molding machine. It is ring-shaped and more convex than the fixed side mounting plate. It is also replaceable.
Guide pins and guide bushings: These guide pins and guide bushings position the cavities and the core. They are made of highly abrasion-resistant materials to withstand mass production.
Cooling water tube: This tube is used to maintain the mold temperature at a constant level. Water is generally used, but oil may be used if the mold temperature is high.
Ejector pin: A pin used to eject the molded product from the mold. It is fixed to the ejector plate.
Return spring: Returns the mounting plate to its original position after the molded product has been ejected.
Return pin: A pin that prevents damage to the cavity side when the ejector pin is left ejected due to some trouble. It also serves to maintain the balance of the ejector.
Fixed-side mounting plate: A plate used to attach to the molding machine. It is connected to the cavity (fixed side mold plate).
Fixed-side mold plate: A plate engraved with the shape of the cavity side of the molded product. It may be nested.
Movable side mold plate: A plate engraved with the shape of the core side of the molded product. It may be nested.
Receiving plate: Supplements the rigidity of the movable side mold plate. The core side may be difficult to cool due to its shape. and...cooling water pipe may be passed through.
Spacer block: A plate that maintains the space for the ejector plate to move.
Ejector plate: A plate to fix the ejector pin and return pin.
Movable side mounting plate: A plate used to mount the molding machine. It is connected to the core (movable side mold plate).
The 2-plate mold has the advantage of low manufacturing cost due to its simple structure. However, since the runner and gate are molded together, there is additional work to be done to cut them. Depending on the molding quantity, it may be necessary to consider hot runners, etc.
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