This trial version can use only a part of item.Function of Major PartsYou will learn about the names and functions of major parts used for an ejection system.A push back pin and a coil spring are used for regular molds, whereas a push back pin and a gas spring are sometimes used for large size molds.This figure illustrates an example of a large mold. Ejector Stopper (Stroke End Pin) A block that stops an ejector plate from going forward [ stop pin]Sprue Lock PinsA pin has the edge of which is undercut to pull a part in mold opening and remove a sprue from a sprue bush.After mold opening, this pin will function as an ejector pin and ejects the sprue from a aprue bush. Also it releases gas contained in molten plastic.Ejector PlateAlso called a push plate. A plate that supports an edge of an ejector pin or a push back pin to eject a part from a mold.It is ejected by an ejector device of a molding machine, and returned to the original position when the edge of a push back pin collides with a cavity plate during mold clamping.Stop PinsA stopper installed to keep an ejector plate horizontal or prevent the ejector plate from retreating too far and damaging a core adaptor plate.Ejector Guide Pins / Ejector Guide BushAn ejector guide pin is also called a push plate guide pin and functions as a guide for sliding of an ejector plate.Because an ejector guide bush slides, a hard material is used.An ejector guide bush is also called a push plate guide bush. It is a cylindrical part used to determine the position by matching the ejector guide pin.Push RodsA shaft linked to the force (hydraulic or mechanical) of the molding machine in order to get the ejector plate to work.Gas Spring / Gas Spring HolderA gas spring forcibly pushes back an ejector plate. The strength of the spring is adjusted by adjusting the filling pressure.When using a gas spring, make sure to avoid high temperature (heat may expand gas, deteriorating the original functions of a gas spring).Calculating Filling PressureTo figure out filling pressure (P) from early load (Wo): P = 100 * Wo /C (C: constant)To figure out corresponding spring constant (K) from filling pressure (P) and gas spring constant (G):K =G * P / 100To figure out force by displacement (x) from the top D.C. of the piston rod (W):W = P (Gx + C)* See the catalog of each manufacturer for constant (C) and gas spring constant (G). A gas spring holder is a block used to fix a gas spring to an ejector plate.Counter bore process for a bolt installation hole, for it also functions as an push rod.
