The injection molding machine manufacturer tells you how to deal with the overflow of the horizontal injection molding machine

    1. Equipment

    (1) Lack of machine clamping force. When choosing an injection molding machine, the rated clamping force of the machine should be higher than the longitudinal projection area of the injection molded product, otherwise it will cause mold shrinkage and flash.

    (2) Poor installation and adjustment of the mold clamping, the toggle mechanism is not straight, the left and right or upper and lower molds are not balanced, and the mold parallelism cannot be reached. The mold is tight on one side and not tight on the other side, and injection burrs appear at this time.

    (3) The mold itself is poor in parallelism, or the device is not parallel, or the template is not parallel, or the tie rods are unevenly distributed, and the deformation is uneven, which will cause the mold to be not tight and cause flashing.

    (4) The non-return ring is worn seriously, the spring nozzle spring is invalid, the barrel or screw is worn too much, the cooling system of the feed inlet is faulty, bridging is formed, the injection volume of the barrel is insufficient, the cushion is too small, etc., if the flash point is repeated , Please repair or change parts in time.

    2. Mold

    (1) The accuracy of the mold parting surface is poor. The movable template (such as the middle plate) is deformed and warped; the parting surface is stained with foreign matter or there are protruding slip burrs around the mold frame; due to the early flash extrusion, the old mold becomes tired and collapsed around the cavity.

    (2) The mold design is unreasonable. The opening position of the cavity is too large, and one side of the cavity will be stretched during injection, forming a flash.

    Plastics have good mobility, such as polyethylene, polypropylene, nylon, etc. They have low viscosity in the molten state and are easy to enter the movable or fixed gap, requiring high mold manufacturing accuracy.

    On the premise of not affecting the integrity of the product, the quality should be placed as symmetrically as possible, and the material should be fed in the thicker part of the product to avoid material shortage and flash. When there is a molded hole in or near the product, a side gate is usually opened on the hole.

    Due to the high injection pressure, if the clamping force is lacking, the supporting force of the mold at this part is lacking, and it will warp slightly and produce flash. If there are moving parts on the side of the mold, the projected area of the side will also be affected by the molding pressure. If the support is lacking, flash will also occur.

    The sliding core has poor matching accuracy, and the deviation of the fixed core and the position of the cavity device will also form flash. Poor venting of the cavity, no venting groove on the parting surface of the mold, or the venting groove is too shallow or deep, or blocked by foreign objects, will form flash. Regarding the multi-cavity mold, pay attention to the reasonable design of each runner and gate, otherwise it will cause uneven filling force and flash.

 3. Process

    (1) The injection pressure is too high or the injection speed is too fast. Due to the high pressure and fast speed, the mold opening force increases, forming a flash. The injection speed and injection time should be adjusted according to the thickness of the product. Thin products should be filled quickly at high speed, and no injection after filling; thicker products should be filled at low speed, and the skin should be fixed before reaching the final pressure.

    (2) The feed speed is too fast to cause burrs. It is worth noting that in order to avoid dents, do not inject too much molten material, so that the dents may not be filled, but flash edges will appear. This situation should be dealt with by prolonging the injection time or holding pressure time.

    Higher barrel and nozzle temperature or mold temperature will reduce the viscosity of the plastic, increase mobility, and flash when it enters the mold smoothly.

    Four, raw materials

    (1) If the viscosity of plastic is too high or too low, it may show burrs. Low-viscosity plastics such as nylon, polyethylene, polypropylene, etc. should increase the clamping force; plastics with strong water absorption or water-sensitive plastics will greatly reduce the active viscosity at high temperatures and increase the possibility of flashing. These plastics should be complete and dry. The viscosity of the plastic that participates in too much recycled material will also decrease, and if necessary, replenish the remaining components. If the plastic viscosity is too high, the movement resistance will increase, and the back pressure will increase the cavity pressure, resulting in a lack of clamping force and flashing.

    (2) When the particle size of the plastic raw materials is uneven, the quality of the feed material changes, the parts are not full, or appear burrs.