Because plastics with high fluidity, such as polyethylene, polypropylene, nylon, and others, have a low viscosity in the molten state and are easy to enter the moveable or fixed gap, the mold’s manufacturing accuracy must be high. It should be situated as close to the center of quality symmetry as feasible to avoid compromising the integrity of the product. To avoid the condition of missing material and a flying edge, the thick portion of the product is fed. When there are creating holes in the middle or near the product, the side gate on the hole is normally opened. Because if the mold closure force is inadequate at high injection pressure, the supporting force of the mold in this section is inadequate, resulting in mild warping and the formation of a flying edge. If the side of the mold contains moveable elements, the forming pressure affects the projection area of the side as well, and if the support is insufficient, the flying edge will result. The sliding core’s accuracy is poor, and the offset of the fixed core and cavity installation location will also result in the flying edge. The cavity’s exhaust is insufficient, and there is no exhaust ditch on the mold’s separating surface, or the exhaust ditch is too shallow, too deep, or obstructed by foreign matter, causing the edge to fly. For a multi-cavity mold, the suitable design of each shunt channel’s gate should be taken into consideration; otherwise, the filling mold’s force would be unequal, and a flying edge would result.

Molding materials that aren’t chosen correctly

Raw material shrinkage has a significant impact on the dimensional accuracy of plastic products. Common Injection Wave Lines are difficult to assure dimensional accuracy of plastic components when the precision of the molding equipment and mold is extremely high yet the shrinkage of raw materials is quite significant. In general, the greater the shrinkage of raw materials, the more difficult it is to guarantee that plastic components are dimensionally accurate. As a result, while choosing a molding resin, we must take into account the impact of raw material shrinkage on the dimensional accuracy of plastic components. The shrinkage fluctuation range for the specified raw materials should not exceed the dimensional accuracy criteria for plastic components.

It should be noted that the shrinkage of various resins varies greatly, and the degree of crystallization of the resin should be considered while analyzing the shrinkage. In general, crystalline and semi-crystalline resin shrinkage is more than non-crystalline resin shrinkage, and the range of shrinkage is also greater, resulting in a bigger shrinkage fluctuation of plastic components. The crystallinity of crystalline resin is high, the molecular volume is small, and the shrinkage of plastic components is significant. The size of resin spherulites has an effect on shrinking as well. Plastic components have little spherulites, a tiny intermolecular gap, and little shrinking, but their impact strength is rather strong.

Overflowing Injection Molding Machine Head: What Causes It

The machine’s actual mold closure force is inadequate. When selecting an injection molding machine, the rated mold closure force must be greater than the tension created by the longitudinal projection area of injection molding goods during injection, otherwise the mold will expand and a flying edge would result. The mold closing device is not adjusted properly, the elbow bar mechanism is not straightened, the left and right or upper and lower closing molds are not balanced, and the mold parallelism cannot be achieved, resulting in one side of the mold being tightly closed while the other side is not tightly attached. During the injection, the flying edge will appear. The mold’s inadequate parallelism, or the mold’s non-parallel installation, or the formwork’s non-parallel formwork, or the pull rod’s uneven force distribution and deformation, will result in the mold not closing and generating the flying edge.

The check ring is severely worn, the spring of the spring nozzle fails, the wear of the material barrel or screw is excessive, the failure of the cooling system at the feed port causes the phenomenon of “bridging,” insufficient barrel adjustment charging quantity and a too small buffer pad can cause the flying edge to occur repeatedly, and the parts must be repaired or replaced as soon as possible. The mold’s separating surface has a low degree of accuracy. Warping and deformation of moveable formwork. The separating surface is discolored with foreign materials, and a projecting skid printing burr may be detected around the mold frame. Due to the early extrusion of the flying edge, the previous mold was fatigue collapsed around the void. The design of the mold is irrational. The mold cavity’s opening position is overly biased, resulting in strain on one side of the mold during injection, resulting in a flying edge.