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Injection molding manufacturers talk about the definition of defects in injection molding products

by:Vowin Rapid Prototyping     2023-02-13
(1) Warpage deformation Injection molding plastic parts deformation caused by internal stress difference or poor cooling in the manufacture of injection molding plastic parts.

(2) Gate pattern There are discernible annular or arc-shaped air marks around the gate, which are in the middle circle if a Chinese gate is used, and concentric circles if a side gate is used.

(3) There are dark areas in the sharp edge material flow area. The surface of the product is very good, until the surface appears dark and rough after the sharp edge.

(4) Voids The voids inside the injection molded products are in the form of round or elongated air bubbles, and the voids often occur in products with relatively thick walls, and they are in very thick places.

(5) Bubbles A certain part of the plastic part is poorly exhausted, and the gas is wrapped in the part to produce circular protrusions on the surface.

(6) Spray pattern When the molten material enters the mold cavity, there is a curved serpentine pattern in the direction of the front end of the fluid. It often occurs in a mold with a large cavity and is formed when the molten material does not directly contact the mold wall or encounter obstacles when filling the mold.

(7) Record grooves Deep grooves can be seen in the entire material flow direction and even to the end of the runner.

(8) Weld line A linear trace on the surface of plastic parts during injection molding is formed by the diversion and convergence of several streams of material in the mold during injection or extrusion. The melts are not completely fused at the interface and cannot be welded together to form a Fusion marks affect the appearance quality and mechanical properties of injection molding plastic parts.

(9) Dark spots, dark lines, embrittlement, burn marks.

①Dark spots and black streaks are dark spots or dark stripes on the surface of injection molded plastic parts, and brown spots or brown streaks refer to the same type of defects.

② Embrittlement is the cracking of materials, which shortens the molecular chain and lowers the molecular weight, resulting in a decrease in the physical properties of injection molded plastic parts.

③ Burn marks are dark or black spots on injection molded parts near the end of the flow path or trapped air.

(10) Flash The sheet with a very thin parting line is the excess material left on the plastic product after the plastic overflows into the gap between the mold clamping surface and the insert during the injection molding process.

(11) Dents Dents are generally caused by a local increase in the shrinkage rate of the product due to the increase in the wall thickness of the injection-molded plastic product. It is the local internal shrinkage caused by gate sealing or lack of material injection;

(12) Lack of material During injection molding, a gap is formed on the surface of the part due to insufficient filling due to insufficient pressure or trapped air.

(13) The local whitening marks on the top white surface are caused by the local external force of the injection molded part, which causes some molecular structures to rearrange or break; it usually occurs at the other end of the ejector rod, which is produced when the product is ejected, by the mold Unsmooth demoulding or uneven product ejection force.

(14) Color difference means that the contrast between the actual product color and the sealed sample color or color plate exceeds the allowable value.

(15) Cold material spot refers to the foggy or bright streaks near the gate of the workpiece or the bend starting from the gate like an earthworm sticking to it.

(16) Cracks and whitening The relatively obvious micro-cracks on the surface of injection-molded plastic parts are called cracks, and the frost-like micro-cracks similar to cracks are called whitening. Both cracks and whitening are micro-cracks without cracks. Environmental stress cracking occurs when injection molded plastic parts are exposed to certain chemical environments or under stress conditions.

(17) Silver thread Injection molding processing plastic parts surface along the flow direction of the needle-shaped silver-white frost-like fine lines.

(18) White line: Under the action of tensile stress, the high polymer produces a whitening striped deformation area due to stress concentration. These striped plane areas strongly reflect visible light, making the surface of the material form a silvery white luster, commonly known as white line.
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