What Is a Core Pin?
A core pin is one of the parts of a mold. It is necessary when making shapes, such as “holes” and “bosses for screw fixation.” The core pin, however, is only a part of creating shapes and does not move, remaining fixed in place even when the mold is opened.
Uses of Core Pins
Core pins are used in molds for molding parts that have shapes, such as “holes” and “bosses for screw fixation”. Since the number of core pins required is equal to the number of “holes” and “bosses for screw fixation,” a large number of core pins are used in molds for parts used in products with many screw fixations. For small precision products, the core pins are also very thin, so care must be taken to avoid damage during molding.
Principle of Core Pins
A rod (pin) shaped part is made according to the diameter and depth of the shape that needs to be molded and is used as a part of the mold component. If the hole itself is deep or the hole itself is deep in the mold shape, the core pin itself needs to be long, making it more difficult to make. If a very long core pin is required, a thicker diameter may be used up to the middle of the pin to ensure strength and only the tip shape may be made to the required narrow diameter. Also, because there is a limit to the minimum distance between adjacent core pins, care must be taken when designing parts that require “holes” or “bosses” in close proximity to each other.
The core pin is a simple shape among mold parts, but due to the characteristics of the processing method of shaving metal, once the core pin is fabricated, “reducing the hole (boss) diameter” may be handled by shaving the core pin again to make it thinner, but “increasing the hole (boss) diameter” requires the core pin to be thickened, which is very difficult to do. However, “enlarging the hole (boss) diameter” is very difficult because the core pin needs to be thickened, and in the worst case, the core pin will need to be remade. Therefore, when designing a part for which “there is still a possibility of adjusting the hole or boss diameter,” it is often more cost and time efficient to first make a mold with a larger hole (boss) diameter and then make fine adjustments in the direction of a smaller diameter.