A, because BMC material contains a lot of glass fiber and filler, it will block the gap and exhaust slot between workpieces during molding. Exhaust is equivalent to discharging, and the exhaust tank should be easy to clean. In places that cannot be cleaned, the parting surface structure and cold material chute should be considered in the design.
B, because the resin and filler will block the gap between the workpieces during molding, it is difficult to disassemble after long-term use and cooling. In addition, the thermal expansion of metal and product accuracy requirements should be fully considered when processing.
C, because the BMC material contains high glass fiber, the fluidity is poor, and the hardness of the material itself is high, which causes great wear on the mold. When designing, different materials should be used in different places, and there are high requirements on the quenching hardness (vacuum heat treatment HRC50 or above), tempering temperature and surface treatment of the die material (it is suggested that the die core should adopt Japanese Datong H 13 or Swedish 8407), so as to effectively ensure the utilization rate of the die.
D, the distribution pattern of cavities should be reasonable: the balance of each cavity in a set of molds is very important, because it is the direct killer of the qualified rate. It also affects the appearance of the product, because when the balance is not good, when the A mold cavity is satisfied, there is a problem with the B mold, and conversely, when the B mold is satisfied, there is a problem with the A mold, which is technically difficult to satisfy.
E.BMC materials are very sensitive to temperature. When the temperature difference is large, the product will be deformed, cracked and the size will be out of tolerance. Therefore, the mold temperature should be detected at multiple points, and the balance of mold temperature should be fully considered when designing the heating rod.
F when designing the runner, the runner should be molded at low pressure and low speed as far as possible, and the position and angle of the runner should avoid directly impacting the easily deformable workpiece and effectively exhausting the gas in the die cavity.