Common plastic product defects
Cracking is a hair-like crack in the finished product, which seriously affects the strength of the product. The main result is as follows:
(1) The mold is not smooth.
(2) Over-saturation of injection molding.
(3) The mold temperature is too low.
(4) The finished product structure is defective.
The flow mark is a trace of the flow of the molten material, and the stripe shape is centered on the gate. The flow pattern is caused by the material injected into the cavity first cooling too fast, and the boundary between the material flowing into the cavity. In order to prevent the occurrence of flow lines, the injection temperature of the material should be increased, the fluidity of the material should be improved, and the injection speed should be adjusted.
Black grain is a phenomenon in which black streaks are produced in the finished product. The main reason for the occurrence is thermal decomposition of the material, which is common in materials with poor heat stability.
The surface of the finished product loses its original luster, and the formation of a milky white film or a blurred state is a phenomenon in which the surface gloss is poor.
The bonding line is a thin line formed by the joining of two or more molten materials, and the reason for the occurrence is as follows:
(1) The mold construction causes the material to flow.
(2) The molten material has poor fluidity.
(3) Foreign matter such as air, volatiles or release agents are entrapped in the junction of molten materials.
(4) The temperature at the junction of the molten material is too low to allow sufficient fusion at the time of joining.
The reasons for insufficient filling are mainly due to inadequate processing conditions, poor mold design, and too thin a finished product.
When the pressure of the plastic in the cavity is too large, the parting force is greater than the clamping force, and thus the die is forced to open, and a burr is generated.
The formation of the ray is generally caused by the rapid start of the rate of fire, so that the air in the cavity can not be pressed out by the molten rubber, and the air is mixed in the rubber, so that the surface gloss and color of the product are uneven, thus affecting the appearance and reducing the mechanical strength. .
There are quite a few reasons for the deformation of the finished product, such as too fast mold, high mold temperature, uneven mold temperature and asymmetry of the sprue system.
When the mold is applied during the processing, the first consideration is whether the injection pressure or the holding pressure is too high. If the injection pressure is too high, the product will be oversaturated and the plastic will be filled into other voids to cause mold release.
The surface of the plastic finished product has depressions and voids, which are called “shrinkage”, thus affecting the appearance of the finished product and reducing the quality and strength. The main reasons for the formation are plastics, processing technology and molds.
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