Today is the day of the end of the month of March 29, and it will take a few days to go to the Ching Ming Holiday. The friends of the vast majority of plastic mold factories can take a break soon. Today, we did not introduce the design of the main channel and positioning ring in the plastic mold manufacturing process. This step is also very critical in the design. If the design is not ideal, it will bring many problems to the following processes.
The gating system consists of four parts: the main channel, the runner, the gate, and the cold material pocket. Taking into account the high appearance requirements of plastic parts, the outer surface does not allow the formation of spots and weld marks, as well as a two-cavity arrangement, ABS is sensitive to the shear rate, etc., the gate is easy to process and trim, easy removal of aggregates and The side gates that will not leave traces on the outer wall of the plastic part will be used, and the mold will use a two-plate mold with a single part surface structure. The mold manufacturing cost is relatively easy to control within a reasonable range.
The main channel is a section of the flow path where the molten material enters the mold first, directly affecting the filling time and the flow speed. The main road is too small, the cooling surface is relatively large during the flow of molten material, the heat consumption is large, and the injection pressure loss is large. However, if the main flow path is too large, plastic loss will occur, the cooling time will be long, vortices and turbulence will occur, and the ability to increase the plasticity of the machine tool will increase. Big. You must choose the right size flow path.
Check the "Concise plastic mold design manual", from the empirical formula, can calculate the main channel is the size, as follows: the relationship between the mainstream channel and the nozzle: SR = R + (1 ~ 2) mm, d = d + 1 mm, the mainstream The radius of the spherical surface is SR=12+2=14mm, and the diameter of the small diameter of the main path is d=3+1=4mm. In order to facilitate the removal of the suspect material from the main channel, the main channel is designed to have a conical shape with a slope of 3 to 6° and a large section of the main flow path of about D=8 mm. In order to allow the melt to smoothly enter the runner, the main flow path Material end design R2 arc transition; To compensate for the deformation of the sprue under the impact force of the nozzle of the injection molding machine, the length of the sprue bushing is designed to be 0.02 mm shorter than the template thickness; the outer radius of the sprue bush shaft shoulder radius R should be larger, take R = 3 mm, in order to avoid quench cracking and stress concentration. The positioning ring is used for positioning when installing the mold. The diameter of the positioning ring of the SYS-30 injection molding machine is 55 mm. The general positioning ring is 5 to 10 mm above the surface of the fixed mold.
Note: The above information from the Jiezheng mold finishing on the Internet, welcome reproduced, indicate the source!