parts molding injection molding processing traces, injection molded parts in the molding injection molding process, in addition to the traces of mold structure molding, there are also traces of molding processing or traces of defects or traces of ills. Some defect marks are caused by improper design of injection molded parts; some are caused by improper mold structure design; some are caused by improper selection of gating system; some are caused by improper injection molding processing methods; Some are caused by the type and quality of materials used and improper additives; some are caused by improper pre-processing or post-processing; they may also be caused by equipment, processing environment and other reasons. Among them, the reason that has a great influence on the mold is caused by improper design of injection molded parts, mold structure design and gating system.
Injection molded parts have traces of injection molding processing, because in this case it is necessary to modify the mold or overthrow the existing mold structure scheme, and then re-design and manufacture the mold to get these defect traces. Sometimes it is not only necessary to redesign the injection mold, but even the injection molded part. In this way, it is necessary to modify the mold or redesign and manufacture the mold, which will inevitably cause a delay in the production time of the mold and injection molding products, economic losses, and even serious consequences of losing the market. Shanghai Mulan Injection Molding Factory, for the traces of defects caused by non-injection molded parts structure, mold structure and pouring system, as long as it passes the test mold, finds out the cause of the defect and then improves the plastic variety, quality, formula, process method, injection molding process, etc. parameters, equipment and injection molding processing environment, etc.
1. Flow marks
Flow marks refer to the appearance of some protruding rough plaques of different sizes on the surface of injection molded parts. Flow marks are defects of the type affected by material flow temperature and mold temperature. Flow marks are mainly formed by the condensed molecular clusters formed by the cooling of the plastic melt during the injection molding process of the injection molded parts, which are scattered in the process and gradually increase during the filling process. Steady flow of material loss and low temperature film front are the main factors that produce flow marks. In addition, the fluidity of the plastic is poor; the material particles are uneven or the material particles are too large; impurities and different types of materials are mixed in the material; the temperature of the mold is low and the temperature of the nozzle is low; the mold has no main runner or the main runner is too short; the mold has no Cold material cavity; nozzle temperature is low, melt temperature is too low, plastic plasticization is poor; plasticization is uneven, injection speed is low, and molding time is short; the capacity of the injection machine is close to the quality of the injection molded part, and the plasticization capacity of the injection machine is insufficient Causes of flow marks.
2. Weld marks
The weld line is also called the joint line, and the weld line belongs to the temperature-affected type of defect. The decrease of material temperature when the plastic melts flow together, the incompatibility of the resin and the attachments, etc. lead to irregular weld marks at the point of flow and fusion of the melts, that is, obvious and thin seams are produced along the surface or inside of the injection molded parts. Wire. The main reasons for weld marks are incompatible plastics and additives infiltrated into the material; improper use of release agents; presence of incompatible oils; use of aluminum foil flake colorants; excessive release agents; molten material inflated Too much; poor plastic fluidity; poor fiber filler distribution; low mold temperature, improper mold cooling system; too many gates; moisture and lubricant in the mold, poor mold exhaust; poor plastic fluidity, fast cooling speed; there are Condensed material, low material temperature; slow injection speed, low injection pressure; poor shape of injection molded parts, too thin wall thickness and uneven wall thickness; low temperature of inserts, too many inserts, poor shape of inserts, etc.
3. Sink marks
Irregular depressions on the surface of injection molded parts are called sink marks, which can also be called sinkholes, dents, depressions, and sags. It is a defect of the type affected by cooling shrinkage. The main reasons are: poor pressure-holding and plastic repair; uneven cooling of injection molded parts; insufficient feeding, insufficient supply, and insufficient remaining material; improper gate position, high or low mold temperature, and easy out of the pool; runners and pouring The gate is too small, the number of gates is not enough, the remaining material is not enough and the pressing time is short; the flow of molten material is poor or the overflow is too much; the material is high, the cooling time is short, and sink marks are easy to appear; the injection pressure and injection speed are slow; the wall is too thick or the wall Uneven thickness causes unequal shrinkage and excessive shrinkage of plastics.
4. Insufficient filling
The plastic melt is not enough to fill the cavity, making the injection molded parts incomplete, which is called insufficient filling or lack of material. Underfill Underfill is a defect of the starvation effect type. The main reasons are insufficient material supply, poor flow of molten material filling, excessive inflation and poor exhaust.
Five, silver streak
Injection molded parts molding injection molding processing traces, silver streaks can also be called water traces or cold traces. Due to the moisture or air in the material or too much volatile matter; the melt is too sheared; the melt and the mold surface are poorly bonded, or rapid cooling or mixed with foreign materials or decomposition and deterioration, Shanghai Mulan Injection Molding Processing Factory The phenomenon that silver-white shiny needle-like stripes or mica flake-like markings appear on the surface of injection molded parts along the flow direction is called silver streaks. The reasons for the occurrence of silver streaks are that the material contains high moisture content, low volatile matter, and the material is filled with gas; improper ingredients, mixed with foreign materials or incompatible materials; small runners and gates; molten material from thin injection molded parts The wall flows into the thick wall; poor exhaust; high mold temperature; moisture on the surface of the mold cavity, too much lubricating oil or release agent, improper selection of mold agent; low mold temperature, low injection pressure, low injection speed; plastic Melt temperature is too high; injection pressure is low, etc.
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