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Author: MULAN -Plastic Molding Manufacturer
Flash, also known as flash and overflow, occurs during the processing of injection molds, and usually occurs at the opening and closing positions of the mold. For example, the parting surface of the mold, the gap of the insert and the hole of the ejector pin. If the overflow cannot be eliminated in time, it will cause partial collapse of the mold injection molding, and even cause permanent damage in severe cases.
In addition, the overflow of the gap between the insert and the hole of the ejector pin will also cause the finished product to be stuck on the mold, which will affect the demoulding process. So why does the injection mold overflow during the processing? How to solve the overflow phenomenon? The following injection mold processing factory will answer for you. 1. Equipment 1. Improper adjustment of the clamping device of the injection molding machine or the unevenness of the toggle mechanism will cause the mold to fail to achieve the proper parallelism, and one side of the mold will be tightly closed while the other side is not tightly connected. It is easy to have spillage during injection.
2. There is a problem with the parallelism of the injection molding machine itself, and the uneven distribution of force on the tie rods will also cause the mold to fail to close tightly and cause overflow. 3. The check ring of the injection molding machine is severely worn, the screw is too worn, the injection volume set by the barrel is insufficient, and the cushion pad is too small, etc., which may cause overflow, so the operator must repair or replace it in time Component. 2. Mold aspects 1. Poor accuracy of the parting surface of the mold The movable template (for example, the middle plate) is deformed and warped, there are foreign objects on the parting surface, and there are prominent skid printing burrs on the periphery of the mold frame. material situation.
2. The mold design is unreasonable (1) If the opening position of the mold cavity is too biased, then during the injection process, the mold will have excessive unilateral tension, resulting in overflow. (2) Plastic materials such as polyethylene and polypropylene have good fluidity, and the viscosity is low in the molten state, which is easy to enter the gap of the mold, so when manufacturing high-precision molds, the operator should be as thick as possible in the mold Feed parts to prevent overflow and affect the integrity of mold products. (3) The poor matching accuracy of the sliding core of the mold or the offset between the installation position of the fixed core and the cavity will also lead to the occurrence of flashing.
(4) For multi-cavity molds, designers should pay attention to the reasonable design of runners and gates, otherwise it will lead to uneven filling force and overflow. 3. Process 1. Under the action of high pressure and high speed, the tension of the mold will increase and cause overflow, so the operator needs to adjust the injection speed and injection time according to the thickness of the mold product. For thin products, high-speed and fast filling is required, while for thick products, low-speed filling is required.
2. In order to prevent the injection mold from sinking, some operators often choose to inject more molten material, but this may not solve the problem, but will cause overflow. Therefore, when we encounter this situation, we should deal with it by prolonging the injection time or holding time. The above is the analysis of the reasons for the overflow of injection molds, mainly from the three aspects of equipment, molds and processes, and I hope it will be helpful to everyone.