-
Injection Molding Defects and Solutions -- Unmelted Lumps
2025-10-20
Cold Slugs / Unmelted Lumps: Unmelted or insufficiently plasticized material enters the mold cavity along with the melt flow, causing hard plastic lumps to become embedded inside or on the surface of the molded part. 20.1 Causes 20.2 Solutions 20.1.1 Material temperature, mold temperature, and nozzle temperature are too low, or injection speed is too slow. 20.2.1 Properly increase the material, mo...
view more
-
Injection Molding Defects and Solutions -- Gate Sticking
2025-10-20
Gate Sticking: The gate sticks in the gate sleeve due to mechanical resistance inside the sleeve, insufficient cooling, or a malfunction of the pull pin. 19.1 Causes 19.2 Solutions 19.1.1 Insufficient runner draft angle, no mold release agent used. 19.2.1 Increase the runner draft angle and apply mold release agent appropriately. 19.1.2 Cooling time too short, nozzle and fixed mold temperatures to...
view more
-
Injection Molding Defects and Solutions -- Plastic Brittleness
2025-10-20
Plastic Brittleness: Due to poor plastic properties, obvious orientation, high internal stress, and poor structural design of the plastic part, the strength decreases, making it prone to cracking (especially along the flow direction of the material). 18.1 Causes 18.2 Solutions 18.1.1 Material degradation, depolymerization, hydrolysis, or poor-quality pigment (e.g. deterioration). 18.2.1 Replace ra...
view more
-
Injection Molding Defects and Solutions -- Uneven Color or Discoloration
2025-10-17
Uneven Color or Discoloration: Uneven color on the surface of a plastic part may result from poor dispersion of pigments or fillers, or from discoloration of the plastic or pigments. If the entire plastic part shows uneven color, it is usually caused by poor thermal stability of the plastic. When the color is uneven at weld lines, it is related to the nature of the pigment. Causes Solutions ...
view more
-
Injection Molding Defects and Solutions -- Ejection Defects
2025-10-17
Poor Demolding / Ejection Defects: Poor demolding occurs when the mold structure is unreasonable, manufacturing precision is insufficient, or overfilling makes it difficult to eject the part. It can also cause the part to be scratched, stretched, or deformed after ejection. 16.1 Causes 16.2 Solutions 16.1.1 Mold surface not smooth. 16.2.1 Polish the mold to meet surface finish requirements; reduce...
view more
-
Injection Molding Defects and Solutions -- Cracks
2025-10-17
Cracks: Cracks occur when poor part design or inferior plastic material properties cause high internal stress, uneven cooling, poor demolding, or other defects. These stresses lead to cracks forming at stress concentration points or near the gate. Under overload or the influence of solvents, these cracks may propagate, resulting in part failure. No. Causes Solutions 15.1.1 Low material temperature...
view more
-
Injection Molding Defects and Solutions -- Black Spots
2025-10-17
Black Spots / Black Streaks: These defects occur when the plastic decomposes or contains volatile substances, air, or other gases that carbonize under high pressure. The carbonized particles are carried by the molten resin into the mold cavity, appearing on the surface of the molded part as black spots, black streaks, or burnt-like marks along the surface. 14.1 Causes 14.2 Solutions 14.1.1 Plastic...
view more
-
Injection Molding Defects and Solutions -- Wrinkles
2025-10-17
Wrinkles / Halo at Gate: When molten resin enters the mold cavity, it suddenly cools near the gate, increasing in viscosity and slowing its flow. Subsequent resin with lower viscosity and higher flow rate quickly fills the cavity. The difference in viscosity between the first-cooled and later-flowing resin causes visible marks where they meet near the gate. 13.1 Causes 13.2 Solutions 13.1.1 Low mo...
view more
-
Injection Molding Defects and Solutions -- S-shaped Flow Marks
2025-10-17
S-shaped Flow Marks (Snake Marks / Jetting): This defect occurs when the molten resin injected from the gate into the mold cavity solidifies on the surface of the molded part in a serpentine, snake-like pattern. 12.1 Causes 12.2 Solutions 12.1.1 Improper gate location, e.g., a direct gate allows molten resin to enter the cavity in a snake-like pattern and solidify quickly without resistance. 12.2....
view more
e-mail
English
français
Deutsch
русский
italiano
español
português
العربية
日本語
한국의
中文