1、 Lack of material
Després que el material fosca entri a la cavitat del motlle, no s’omple completament, donant lloc a l’escassetat de peces de plàstic.
Causes i mesures de combinació:
(1)Improper selection of equipment: when selecting equipment, the amount of melt glue on the machine must be greater than the amount of melt glue on the products, and the weight of peces modelades per injecció can only account for 85% of the total amount of melt glue on the machine.
(2) Insufficient material supply: if there is bridging phenomenon at the feeding port, the screw injection stroke can be increased appropriately to increase the material supply.
(3) Poor fluidity of raw materials: improve the retention defects of the mold pouring system, reasonably set the pouring position, expand the gate, flow channel and the size of the injection gate, and use a larger nozzle to properly increase the temperature of raw materials.
(4) Unreasonable design of gating system: when designing gating system, attention should be paid to gate balance, which is proportional to the weight of plastic parts in the mold cavity and gate size. It is that each mold cavity can be filled at the same time. The gate position should be selected at the original wall position, or the design scheme of balanced layout of runner can be adopted.
(5) Mala escapament del motlle: comproveu si hi ha una cavitat de material fred o si la posició és correcta. Al motlle amb cavitat profunda, s'afegirà una ranura d'escapament i un forat de ventilació a la part inferior injectada. Es pot obrir la ranura de sortida amb una profunditat de 0. 02-0. 04 mm i ample de 5-11 mm a la superfície de tancament. El forat de ventilació s'ha de situar a la posició final d'ompliment de la cavitat del motlle.
(6) In the aspect of process operation, we can improve the mold temperature, reduce the injection speed, reduce the resistance of the gating system, and reduce the closing force.
(7) La temperatura del motlle és massa baixa: s'ha d'escalfar prèviament la temperatura requerida pel procés abans de començar -. Si la temperatura del motlle no augmenta, comproveu si el disseny del canal d’aigua del motlle és raonable.
(8) Insufficient injection pressure: the injection pressure and the length of the die are close to a positive proportion. The injection pressure is too small, the length of the die is short, and the cavity filling is not enough. Therefore, the injection pressure can be increased by slowing down the injection forward speed and extending the injection time appropriately.
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2、 Deformation
Com que la contracció interna del producte és inconsistent, l’estrès intern és diferent i es produeix la deformació.
Causes i mesures de combinació:
(1) Orientació molecular desequilibrada: per tal de minimitzar la guerra provocada per diferents orientacions moleculars, s'han de crear condicions per reduir la pàgina de guerra. Orientació de flux i relaxació de la tensió d’orientació: el mètode més eficaç és reduir la temperatura del plàstic i la temperatura del motlle. Quan s'utilitza aquest mètode, és millor combinar-se amb el tractament tèrmic de les peces de plàstic, si no, l'efecte de reduir la diferència d'orientació molecular sol ser curt -. El mètode de tractament és que la tensió d’orientació de la part de plàstic es pot eliminar en gran mesura quan la part de plàstic es desemmotlla i mantenir a alta temperatura durant un cert període de temps i després es refreda lentament a temperatura ambient.
(2) Improper cooling: when designing the structure of plastic parts, the section thickness of each part should be consistent as much as possible, and the plastic parts must be kept in the mold for sufficient cooling setting time. For the design of mold cooling system, it must be noted that the cooling pipe should be set in the position where the temperature is easy to rise and the heat is relatively concentrated. For those parts which are easy to cool, slow cooling should be carried out as far as possible to make the cooling of all parts of the plastic parts balanced.
(3) the first mock exam is not enough. The edges are not light. The plastic parts have a slope when designing the mold. If a product & #39;s uneven slope is distorted, the product will be rough and rough. In the design and acceptance of the mold, the angle of the supporting film and the smoothness of the edge should be considered.
(4) Cooling time: when the vulcanized plastic is filled into the mold cavity, there must be cooling time. The cooling time will cause the product ejection deformation. The product is not sufficiently cooled. When ejection, the product will also deform if it is relatively soft. If it is too slow, the product will completely cool in the mold cavity and ejection has no elasticity. The hardtop product will also deform, so the cooling time should be set appropriately.
(5) Injection process: injection process, pressure, speed, time, location, can make the product deformation. When setting the parameters, it should be considered repeatedly. When adjusting the machine, adjust the parameters slowly in 1 unit to obtain the best parameters.
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3、 Phimosis
Quan el fós de plàstic és forçat a sortir del motlle des de la superfície de separació. Es forma un flaix quan la cavitat produeix un full.
Causes i mesures de combinació:
(1) Insufficient clamping force: when the clamping force of the injection molding machine is too low to maintain the clamping force of the mold, the flashing will occur. It is necessary to adjust the area of the plastic part and the molding pressure to see whether they exceed the rated clamping force of the equipment and improve the clamping force. If they exceed the limit, the machine with large tonnage can be replaced, and the injection pressure, mold temperature, injection speed, time and position can also be adjusted from the process of adjusting the machine.
(2) Material temperature is too high: the plastic temperature is too high, resulting in the melt viscosity is too low and the material overflows between the templates. You can manually spray glue to observe the fluidity of the raw materials. You should properly reduce the material temperature, and at the same time, try to precisely process the mold to reduce the mold gap.
(3) Mold defect: mold defect is the main cause of overflow flash. Carefully check whether there are sundries in the mold closing surface and guide pillar hole, resulting in the mold not being closed. Whether there is balance between the mold templates, whether there is bending deformation, and whether the opening distance of the template is adjusted to the correct position according to the thickness of the mold. Whether the lock module surface is damaged, whether the pull rod is deformed unevenly, and whether the exhaust slot hole is too large and too deep. If the formwork deformation is caused during forming, the supporting formwork or thickened formwork shall be added to prevent the formwork deformation.
(4) Improper control of process conditions: the injection speed is too fast, the injection time is too long, the injection pressure is not evenly distributed in the mold cavity, the filling speed is not balanced, and the feeding amount is too much, resulting in flash and drape. Taking corresponding measures to reduce the filling speed, especially the speed close to the completion of filling, the injection pressure and the holding pressure, can reduce the required clamping force and avoid using too low
