What are the main defects of common plastic products?
Warpage, deformation: due to forming residual stress, shear stress, cooling stress force and uneven shrinkage caused by insufficient cooling, demoulding; bad, plastic products, insufficient strength, mold deformation and other reasons, the plastic products shape distortion and warpage from Kong Pian, such as the phenomenon of uneven wall thickness.Crack: due to plastic stress is too large, poor cooling, demoulding unevenness, poor performance of plastic or plastic products of poor design and other ills (such as deformation) and other reasons, make plastic products surface and feeding additional fine cracks, or cracking or in the load and the effect of solvent cracking phenomenon.Black spot, a plastic material or due to decomposition of combustible volatiles and air combustion decomposition under high temperature and high pressure combustion with the melt into the cavity, showing black spots, black stripes on the surface of plastic products, plastic products, or along the surface is like carbon burn phenomenon.
Poor welding: due to the melting of material, the drop of the material temperature at the confluence, the failure of the resin and the inclusion compound, etc., causes the welding material to flow into the confluence and the welding is bad and produces a fine fine seam along the surface or inside of the plastic product.Because of the melt along the surface of the mold surface is not smooth flow to fill the cavity, but into a semi solidified state of fluctuation along the cavity surface of the melt flow or a stagnation phenomenon.Silver markings: as the material in water or air, and volatile matter too much, the melt shear effect is too large, the melt and mold surface sealing side, or rapid cooling or mixing of different materials or decomposition of metamorphism, and make plastic products surface appearance of silver white luster along the direction of flow of the needle like stripes or mica makeup markings (water traces).
Plastic products: mainly due to insufficient feeding, the melt filling flow is bad, too much inflation and bad exhaust causes to fill the cavity with plastic products shape incomplete or multi cavity individual cavity filled with.Dimensional instability: mainly due to poor strength of the die, poor precision, unstable injection molding machine and unstable forming conditions, the size of plastic products is unstable.Bubble: residual gas in plastic products due to melt inflated excessive or bad exhaust, and a small hole or clusters (note and vacuum bubble difference).Collapse (dent) or vacuum bubble: due to poor packing, poor cooling of plastic products, uneven wall thickness and high shrinkage of plastics.Flying too large: due to poor mold, the gap is too large, plastic flow is too good, too much feeding, plastic products along the edge of the thin thin wings.
Uneven color or discoloration: discoloration of plastic or pigment due to improper distribution of pigments or fillers; uneven color on the surface of plastic products. Uneven color varies with the appearance of the reasons. Near the inlet is mainly uneven distribution of pigments, such as when the whole plastic products uneven color is caused by poor thermal stability of plastic, and the uneven color of the weld site is related to the nature of the pigment.Plastic products are fragile: because of bad plastics, obvious directionality, internal stress and plastic structure is not good, so that the strength of plastic products decreased, brittle, easy to crack (especially in the direction of material flow easier to crack).Bad mold release: because of excessive filling effect, bad mold release performance and other reasons, make plastic products difficult to release or after the release of plastic deformation and rupture, or plastic products residual direction does not meet the design requirements.
