We are a professional Injection mold maker, let's introduce the principle of core pin perforation.
The core pin used to perforate the part should be hardened rather than nitrided. Most of the ejector pins and pins are nitrided, with a surface hardness of 65 to 74 Rockwell C (Rc), and a core hardness ranging from 40 to 55 Rockwell hardness, depending on the supplier and the type of pin. The surface hardening is usually only 0.001 inches. 0.007. Deep and fragile. This may result in chips on the edge of the pin during the production process.
However, some thimbles can be cured under a through-hardening condition, typically 58 to 62 Rc, but a lower hardness of 50 to 55 Rc can also be found. You might consider using one of these penetration hardened ejector pins in a core pin application because the ejector pin diameter tolerance is approximately -0.0003 to -0.0005 inches. In the case of wear or corrosion in the future, the ejector pin can be replaced with a core pin with a tolerance of +0.0003 to +0.0008 inches
The core pin is usually made of H-13 or M-2 tool steel. The standard hardness of H-13 pins is 30 to 35 reinforced concrete. The higher hardness H-13 core pin is also available in the market with a hardness of 50 to 55 Rc, and the M-2 pin has a hardness of 60 to 63 Rc. In this case, the core pin butts in the cavity or another pin.
Here, two opposite core pins collide with each other. For this type of application, the use of a through-hardened core pin is necessary. Spring loading one of the pins will greatly extend the life of both pins. I want to know how many of you realize that this painting is wrong. (Yes, this is a test.) Since the core pin on the core side of the mold is spring-loaded and the hole is back-bored, the spring-loaded pin will try to push the molded part away from the core-possibly causing it to get stuck in the cavity.
When the hole on the part is quite long and the hole diameter is quite small, two opposite core pins are usually used to reduce the length. If two pins have the same diameter, one of them should be intentionally slightly larger than the required hole diameter. If one of the pins deflects due to the flow of molten material, a screw, pin, or another object can pass through the hole unimpeded.
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