Los plásticos de PC tienen excelentes propiedades, alta transparencia, buena tenacidad al impacto, resistencia a la fluencia, amplio rango de temperatura. Los plásticos de PC tienen las siguientes características de proceso
La sensibilidad de la viscosidad de la masa fundida a la velocidad de corte es pequeña., pero la temperatura es grande, no hay un punto de fusión obvio, the viscosity of melt is high, the resin is easy to hydrolyze at high temperature, and the product is easy to crack. En vista de estas características, special attention should be paid to differential treatment: para aumentar la fluidez de la masa fundida, it is not achieved by increasing the injection pressure but by increasing the injection temperature. The runner and gate of the mould are required to be short and thick, so as to reduce the pressure loss of the fluid and have a higher injection pressure. The resin shall be fully dried before forming and processing to control its moisture content below 0.02%. Además, insulation measures shall be taken for the resin during processing to prevent moisture absorption again. It is not only necessary to design the products reasonably, but also to master the forming process correctly, such as increasing the mold temperature, post-treatment of the products and so on, which can reduce or eliminate the internal stress. Adjust the process parameters in time according to the different conditions of the products.
Process characteristics of PC: PC viscosity is large, melt temperature is high, and fluidity is poor. En este caso, it must be injection molded at a higher temperature (270 ~ 320 ℃), relatively narrow range of material temperature adjustment, and the processibility is inferior to PMMA. The injection pressure has little effect on the fluidity, but because of the high viscosity, the injection pressure still needs to be higher. Para prevenir el estrés interno, el tiempo de mantenimiento de la presión debe ser lo más corto posible. La tasa de contracción es grande y el tamaño es estable., pero la tensión interna del producto es grande y fácil de romper, so it is better to improve the fluidity by increasing the temperature rather than the pressure, and reduce the possibility of cracking by increasing the temperature of the mold, improving the structure of the mold and post-treatment. Cuando la velocidad de inyección es baja, the gate is easy to produce corrugations and other defects. La temperatura de la boquilla radial debe controlarse por separado., la temperatura del molde debe ser alta, y la resistencia del corredor y la puerta debe ser pequeña.
Injection molding performance of PC: PC is a crystalline plastic with obvious melting point. It melts at 220 ℃ and decomposes at 350 ℃; the general processing temperature is 250-320 ℃; it absorbs water and a small amount of water can cause it to decompose at high temperature. Durante el moldeo por inyección, it must be dried, and the drying temperature can be used at 120 ℃ for 4-5h; the melting viscosity of PC material is large, so it needs a large pressure during injection molding; In the processing of PC plastics, if the conditions permit, the mold temperature can be increased by the mold temperature machine to reduce the residual stress of the product; if the product has inserts, the diameter of the inserts is less than 1-2mm, preheating can be ignored, and the larger inserts should be considered preheating, de lo contrario, stress cracking will occur; The shrinkage of PC has nothing to do with the processing conditions and the wall thickness of the products. Its longitudinal and transverse shrinkage are relatively close, so it can be processed into products with high precision. Its shrinkage is 5 ‰ and the overflow value is 0.05mm.
(1) Temperatura de inyección
It can only be made after considering the shape, Talla, estructura del molde, product performance, requirements and other aspects of the product. Generalmente, when the temperature is between 270 ℃ y 320 ℃, si la temperatura del material es superior a 340 ℃, PC se descompondrá, the color of products will become darker, and defects such as silver wire, franja oscura, punto negro, bubble will appear on the surface, and the physical and mechanical properties will also decline significantly.
(2) Presión de inyección
It has a certain influence on the physical and mechanical properties, tensión interna, molding shrinkage of PC plastic products, and has a great influence on the appearance and demoulding performance of products. Too low or too high injection pressure will cause some defects of products. Generalmente, the injection pressure is controlled between 80 ~ 120MPa for thin-walled, proceso largo, complex shape and small gate products, in order to overcome the melt flow Resistance, so that even if the mold cavity is full, a higher injection pressure (120-145mpa) can be selected to obtain a complete and smooth surface of the product.
(3) Pressure maintaining pressure and time
The magnitude and duration of holding pressure have great influence on the internal stress of PC products. Too small holding pressure, small feeding effect, easy to appear vacuum bubble or surface shrinkage; too large holding pressure, easy to produce large internal stress around the gate. In actual processing, the method of high material temperature and low holding pressure is often used to solve this problem. The selection of holding time depends on the thickness of products, tamaño de la puerta, temperatura del molde, etc. generalmente, small and thin products do not need a long holding time; on the contrary, large and thick products should have a long holding time. The length of holding time can be determined by the test of gate sealing time.
(4) Velocidad de inyeccion
There is no obvious effect on the performance of PC products. Excepto para paredes delgadas, puerta pequeña, productos de pozo profundo y proceso largo, generalmente se adopta un procesamiento de velocidad media o lento, multi-level injection is preferred, and slow fast slow multi-level injection is generally adopted.
(5) Temperatura del molde
Generalmente, it can be controlled at 80-100 ℃, and it can also be increased to 100-120 ℃ for products with complex shape, thinner and higher requirements, pero no puede exceder la temperatura de deformación en caliente del molde.
(6) Velocidad del tornillo y contrapresión
Due to the high viscosity of PC melt, the requirement of screw speed should not be too high to prevent the screw from being overloaded, which is favorable for the maintenance of plasticizing, exhausting and injection molding machine. It is generally suitable to control the screw speed at 30 ~ 60R / min, while the back pressure should be controlled at 10% ~ 15% de la presión de inyección.
(7) release agent
En el proceso de moldeo por inyección., the use of release agent should be strictly controlled, and the use of recycled material should not exceed three times, and the use amount should be about 20%.
(8) It is required that the maximum injection volume (including flow channel, portón, etc.) of PC products should be no more than 70% ~ 80% of the nominal injection volume
The length diameter ratio (L / D) of the screw is 15 ~ 20, and the set compression ratio is 15 ~ 20
Acerca de JasonMould Industrial Company Limited
Jasonmould es un Fabricante de moldes de China de moldes de plástico- molde de inyección, moldes de fundición a presión, moldeo por soplado de plástico, moldeo rotacional, médico moldeo por inyección de plástico, dos disparos moldeo por inyección de plástico, moldeado de inserción, sobremoldeo, moldeo por inyección de metal, micro moldeo por inyección, moldeo por inyección de polvo, moldeo por inyección de cerámica, moldeo por inyección de líquido, moldeo por inyección husky, molde del hogar, molde de fundición, morir herramienta de molde, moldes personalizados, moldes de porcelana, herramientas de creación rápida de prototipos, herramientas de creación de prototipos de plástico, herramientas de punzonadora, matriz y herramientas para piezas de teléfonos móviles / celulares, piezas de automóviles, aspiradoras, herramientas recargables, telefonos, fotocopiadoras, ordenadores, altavoces multimedia, y muchos otros productos electrónicos y electrodomésticos.. Y también un fabricante de productos de plástico., fabricante de moldes China- Partes plásticas, tanque de agua de plástico, bolas de plastico, contenedores de plástico, hebilla de plastico, ancla de plastico, percha de plastico, cuchara de plástico, accesorio de tubería de plástico, caída de plástico, vajilla de plastico, copas de plástico, botellas de plástico, bandeja de plástico, envase cosmético de plástico, Contendor de plastico, recipiente de plástico para alimentos, sillas de plastico, Tapas de plástico, cierre de tapa de plástico, tubos de plastico, tuberías de agua de plástico, perillas de plástico, tubo de plastico, cajas de plástico para uso general, rejillas de plástico, etc..
Contacto:
Persona: James Yuan
Empresa: JasonMould Industrial Company Limited
Agregar: Pueblo LongGang,Ciudad de LongXi,Condado de BoLuo,Ciudad de HuiZhou,La provincia de Guangdong, porcelana
Tel: 86-752-6682869
Correo electrónico: [email protected]
Sitio: https://www.jasonmolding.com/custom-injection-molding/
