Some suggestions for bmc injection molding machine to see if they can help you
BMC is also known as "bulk molding compound". The high-precision bmc injection molding machine is made of unsaturated polyester resin, low shrinkage/low profile additives, initiators, internal release agents and mineral fillers, which are premixed into a paste, then added with thickeners and colorants, and mixed with glass fibers of different lengths in a special kettle. After thickening, it forms a bulk intermediate material.
The main molding methods of BMC are compression molding, transfer molding and injection molding.
In recent years, with the continuous progress of injection molding technology, BMC's injection molding is increasing. Because BMC is a thermosetting plastic, based on the material characteristics, it is required that the barrel temperature of the injection molding machine should not be too high to facilitate the material flow. Therefore, in the injection molding process of BMC, it is very important to control the barrel temperature. A set of control system must be established to ensure the suitability of temperature, so that the temperature from the feeding section to the nozzle can reach a good state.
Generally, the injection molding machine used for molding BMC has a set of hydraulic system in the feeding part to force the lump material into the barrel when the screw pushes the material.
Based on experience, the following suggestions are put forward for BMC's injection molding machine selection and molding:
★ According to the viscosity of the raw material of the bmc injection molding machine, select the appropriate screw to push the material.
★ BMC is difficult to feed due to its lumpy form, so the forced feeding device (feeding extrusion) shall be used for material supply. When feeding, BMC can be regarded as a premix that has been plasticized. The screw does not play the role of plasticizing, but only mixing, conveying and metering.
★ The counterflow ring of screw device shall be made of wear-resistant material to avoid screw wear.
★ The nozzle shall be a long nozzle with cooling cover.
★ The forward and backward feeding device of the nozzle is preferably driven by the hydraulic cylinder, which corresponds to the movable sprue plug, improves the pressure stability of the nozzle top and reduces the maintenance cost.
★ Because BMC contains glass fiber and dust, in order to avoid dust adhering to the ball screw and belt, special sheet metal design and closed servo motor are required.
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★ According to the characteristics of easy curing of materials, the injection and metering high load servo motor is adopted.