Injection compression molding technology

Injection compression molding (injection compression moulding / icm) is an advanced traditional form of injection molding. It increases the flow of injection molding parts length / thickness ratio; a smaller clamping force and injection pressure; reduce material stress; and improve processing productivity. Injection compression molding of thermoplastic engineering plastics for the production of various products, such as: large-size surface parts, thin wall, miniature components, optical lenses, and have good resistance to attack characteristics requirements of the parts. The main features of injection compression molding process compared to traditional injection molding, injection compression molding a significant feature is that the mold cavity space can be automatically adjusted according to different requirements. For example, it can be injected into the cavity before the material is not so oriented part of the mold has closed, and the cavity space is expanded to twice the wall thickness of parts completed. In addition, also according to different mode of operation, the material injected during or after the end of the injection cavity space the size of the corresponding control, so that compatible with the injection process, so that the pressure to maintain an appropriate state of the polymer, and to compensate for shrinkage effect. According to the geometry of injection molding parts, surface quality requirements, and different conditions of injection molding equipment, injection of contraction Protection Division Four to choose from. They are: sequential; were acting; breathing and partial pressure. Sequential icm (seq-icm) sequential injection compression molding process, the injection mold cavity of the push operation and cooperation is the order carried out. Initially, some slightly closed mold guide, and a part wall thickness is about twice the cavity space. When the resin into the mold cavity, the active portion of the drive until it closed mold and make the polymer in the cavity is compressed. In this process, due to begin from the completion of compression will be injected into the flow of a polymer suspension and static moment, which may be in part formed on the surface of a flow line traces, their visibility depends on the color of polymer materials, as well as forming part when the texture and material type. The ways of operation. Crank rod device can be used to carry out such icm. Were acting icm (sim-icm) with the same sequential icm, icm were acting started in part when the mold guided closed slightly different starting materials into the cavity at the same time, the mold began to push the co-Shi pressure. The extrusion feed screw and the mold cavity in the joint campaign period, there may be a delay of s2 or s2. Since the polymer flow front has maintained a steady flow state, it does not appear seq-icm processes, such as the suspension and the surface traces of the flow lines. Since these two ways are left in the beginning of the operation a large cavity space, and in the molten polymer into the direction of the cavity pressure has not yet met, it may be because of gravity and the first side into the lower cavity and can not be under pressure due to a temporary state in the emergence of unwanted foam. Moreover, the greater part wall thickness, the cavity space will be larger, while the streamer extension will increase the length of time the mold completely closed cycle, which may cause this phenomenon increased. Breathing icm (breath-icm) with breathing icm, the beginning of the injection mold is completely closed state. Therefore, once injected into the polymer will remain in the state of compression. This two ways to overcome the above potential problems that may arise. When the polymer into the cavity, the mold is gradually opened and the formation of a large cavity space, and the cavity of the polymer that is always maintained at a certain pressure. When the material close to the full cavity, the mold has begun to push back together until it is closed, the polymer further reduce the demand and achieve the completion of part thickness. The movement between the mold cavity expansion may aid the spread of polymer injected into the cavity pressure or pre-injection molding machine exercise program to achieve. Local pressurized icm (select-/com-icm) \ r \ n type or the use of local pressure, said line pressure type icm, the mold will be completely closed state. Has a built-in line pressure head in the polymer after injection or injection from a local location of the cavity pressure to the cavity, so that part of the larger entity and is part of local compression pressure thin. This partial pressure, injection equipment or through a separate line of the first hydraulic device default built-in procedures to control. Injection molded parts and injection mold design for injection compression molding of parts with surface appearance, such as portable computer casings, car tailgate, dashboard, and the relatively flat such as a car fender. To choose a good part of the entrance will be marked and live streaming channel location, so to fill the cavity with good results. Some commercial injection molding filling process can be used to detect pushing force and injection pressure. For the development of some of the standard rules of plastic can also be used, such as strengthening ribs / wall thickness ratio, and some combination of technologies. Note the orientation of the die out of orbit and the orientation of the core edge and the cavity. With a tight tolerance to prevent polymer leakage overflow cavity. Have a switch with a nozzle check to prevent the polymer back into the injection molding machine. Mold can also install a check valve with a nozzle instead of the hot injection nozzles. For through-hole parts, it should be so fixed in the mold side of the nail penetration of the other side of the slide die and have a good match, forcing the pin to prevent loosening of the mold cavity movement or stuck. In addition, because the icm injection molding process, the cavity pressure is lower than the traditional injection molding, so do not like a traditional injection mold structure when it was a solid heavy. Icm push of the injection molding equipment and feed screw clamping force of the movement of the corresponding conventional injection molding operation is different, it is necessary to add some software features injection molding machine. In order to obtain such sim-icm and breath-icm mold and screw the same time exercise, injection molding machine hydraulic fluid flow must be improved. In addition, the main hydraulic equipment for seq-icm injection, you can use for traditional injection locking of the hydraulic valve, push the movement to achieve die. \ R \ n most of the hydraulic injection molding equipment can be used for large parts of the injection compression molding. But for the closed cavity should use pre-programmed exercise program to control the pressure, otherwise they will experience difficulties. \ R \ n should pay attention to the movement of the mold cavity is linear, because the non-linear flow mold Games temporary effect of the polymer occurred, resulting in strange parts of the surface appears shiny appearance. As icm injection can have longer than the traditional streamer length and lower locking force and injection pressure, it can use a smaller than conventional injection molding equipment to produce large parts. Tests conducted on noryl gtx964 that wall thickness in the same conditions and part geometry, icm less than the traditional injection molding clamping force seventy-five percent, and reduce the thirty percent of the injection pressure. The use of sim-icm production of body panels of the test is that, when the casting mold by the Central Road and part wall thickness of 1.5mm, the length of the streamer growth of two hundred percent than traditional injection molding. In addition, the clamping force reduction to a large extent also depends on when the mold is closed, locked too fast or too slow it will increase the injection pressure and clamping force. Injection compression molding has been successfully applied for many years, and its operation is also relatively easy. With proper design specifications, and the use of appropriate materials and processes, it is entirely possible for the existing injection molding equipment with some adjustments to the software to achieve operation. icm compared with traditional injection molding, and its advantage is a larger proportion of streamer length of the wall thickness; clamping force and injection pressure can be reduced, and smaller on the production of large parts of injection molding equipment; it also lower the material within the stress, and refraction of light on the good results, so suitable for producing optical products such as cds, dvss and eye lenses and so on.