Injection molding common problems - air marks

What causes air marks?

The surface of the plastic part has tree-shaped and wavy scratches centered on the gate. The temperature of the mold and the nozzle can be increased, the injection molding rate and filling speed can be increased, and the injection pressure, holding pressure and filling time can be increased. The following is a detailed introduction by Shanghai Ma Chitian Injection Mold Factory how to avoid air marks in injection molded parts.

An electric heating device can also be installed at the gate to increase the temperature of some gates. The area of ​​the gate and the runner can also be enlarged appropriately, and the cross-section of the gate and the runner is preferably circular.

In addition, a large cooling hole should be provided at the bottom of the gas port and at the end of the channel. Feedstock temperature is of particular importance to the detriment of solution flow characteristics. More attention should be paid to the specifications of the cold hole, and the position of the cold hole should be set in the solution as much as possible, and the tail of the flow direction is along the inlet. The flow of molten raw material in the flow safety outlet is unstable, causing helical wave flow scratches on the surface of plastic parts.

When the melt is introduced into a cavity with a very large cross-section from a narrow section of the flow-relative path, or the flow-relative path of the plastic injection mold is narrow and the gloss is poor, the flow is likely to cause stable seepage, which will cause waves on the surface of the spiral plastic prefabricated component flow. At this level, the introduction speed can be appropriately reduced, or the introduction speed can be controlled slowly, quickly, and slowly.

Volatile organic compound gases cause cloudy, wavy air marks on the surface of plastic parts. Use when using. ABS or other polymer epoxy resin raw materials, if the temperature is too high during injection molding, the volatile organic compound gas caused by epoxy resin glue and lubricant is likely to cause cloud wave gas traces on the surface of plastic prefabricated components. At this level, try to reduce the temperature of the plastic injection mold barrel, improve the exhaust pipe setting of the mold, reduce the temperature and filling rate of raw materials, and expand the gate cross section as much as possible.