What are the common problems of mold trial (2)

Update: 22-10-2021

9. Mica flake delamination and peeling: Due to the mixing of foreign materials or low mold temperature, the shearing effect of the molten material is too large when it flows along the surface of the mold, causing the material to peel off in a thin layer, and the physical properties are reduced
10. Gate sticking: Due to mechanical resistance in the sprue sleeve, insufficient cooling or failure of the pull rod, the gate sticks in the sprue sleeve
11. Poor transparency: due to poor contact between the molten material and the mold surface, small cavities on the surface of the plastic part cause random light emission or plastic decomposition, foreign matter impurities, or the mold surface is not bright, making the transparency of the transparent plastic poor or uneven
12. Silver wire markings: due to the presence of moisture or aeration in the material, and too much volatile matter, the molten material is subjected to excessive shearing, the molten material is not closely attached to the mold surface, or the molten material is rapidly cooled or mixed with foreign materials or decomposed and deteriorated. Make the surface of the plastic part appear silver-white glossy needle-like stripes or mica flake-like stripes along the material flow direction
13. Warpage and deformation: internal stress caused by residual stress, shear stress, cooling stress and uneven shrinkage during forming; poor demolding, insufficient cooling, insufficient strength of plastic parts, mold deformation, etc., make plastic parts occur Distortion of shape, uneven warpage or hole deviation, uneven wall thickness, etc.
14. Cracks: due to excessive internal stress of the plastic part, poor demolding, uneven cooling, poor plastic performance or poor design of the plastic part, and other maladies (such as deformation), fine cracks occur on the surface of the plastic part and near the inlet , Or cracking or no cracking occurs under the action of load and solvent
15. Black spots and black bars: Due to the decomposition of plastic or the flammable volatile matter in the material, air will decompose and burn under high temperature and high pressure. The surface of the plastic part is charcoal burned
16. Uneven color or discoloration: Due to poor distribution of pigments or fillers, the discoloration of plastics or pigments has uneven color on the surface of the plastic parts. Uneven color varies with the appearance of the phenomenon. The cause is also different. The pigment distribution near the feed inlet is mainly caused by the uneven color of the entire part. It is caused by poor thermal stability of the plastic. When the color of the welded part is uneven, it is related to the nature of the pigment. About these are the more common mold trial problems of injection molds

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