What is the reason for burrs on injection molding products?

Router Injection Molding Products flash is also called overflow, burr, etc. It mostly occurs at the parting position of the mold, such as the parting surface of the dynamic mold and the static mold, the sliding part of the slider, the gap of the insert, the hole of the ejector pin, etc. Flash is largely caused by the failure of the mold or machine clamping force. There may be the following reasons:

1. The maximum clamping force of the machine is not enough. A machine with sufficient clamping force should be selected. The clamping machine hinge is worn or the sealing element of the clamping cylinder is worn, resulting in oil dripping or backflow, causing the clamping force to decrease. The actual temperature is too high due to the loss of control of the heating system. Check whether there are problems with the thermocouple, heating coil, etc.

2. (1) The uneven distribution of the mold cavity or the lack of parallelism causes unbalanced force and causes local flash. Local dissatisfaction should be placed at the mass symmetry center as much as possible without affecting the integrity of the product. (2) Flash will be caused when the movable components and sliding cores in the mold are unbalanced. (3) When the mold is not well vented, the compressed air will cause the mold parting surface to expand and flash to appear. A good venting system should be opened, or a venting groove should be dug on the parting surface.

3. The fluidity of the plastic is too high, or too much lubricant is added. The pressure, speed, temperature, etc. should be appropriately reduced to reduce the amount of lubricant used. If necessary, plastic with low fluidity should be selected.

4. Processing and adjustment: (1) The set temperature, pressure, and speed are too high. Segmented injection should be used. Excessive injection time, holding time, and feed amount will cause flash. (2) When adjusting, the clamping machine hinge is not straightened, or the mold adjustment nut often moves when opening and clamping the mold, resulting in insufficient clamping force and flash. (3) The parallelism between the adjustment head and the diode is not enough or the pressure of the adjustment system is too high. 5. Reasons for repeated flash and part dissatisfaction: (1) When the particle size of the plastic raw material is very different, the amount of feed will be uncertain. (2) The wear of the screw’s rubber head, rubber ring and rubber gasket is too large, so that the molten material may slide and flow back between the screw and the barrel, causing flash or dissatisfaction. (3) The cooling system of the inlet fails, causing the feed adjustment. (4) The injection amount set by the barrel is insufficient, that is, the buffer pad is too small, which will cause the injection to be more or less, resulting in flash or dissatisfaction of the workpiece.