Designing the purpose of venting: The gas in the mold includes not only the air in the cavity but also the air in the flow path and the decomposition gas generated by the plastic melt. The design of the exhaust system on the mold is to make these gases smoothly excluded.
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The danger of insufficient venting
On the surface of the rubber parts, baking, air, and seams are formed to make the surface contour unclear. Difficulty in filling, or partial flashing. In severe cases, there is scorch on the surface. Reduce the filling speed and extend the molding cycle.
Venting system design
The commonly used exhaust methods are as follows: Partition surface open exhaust slot In order to make the molten plastic into the cavity, the exhaust is smooth, avoid the product from trapping and burning, and the exhaust groove should be processed on the parting surface.
1) When the parting surface is closed, it needs to be connected with an exhausted groove at the outer end of the exhaust groove to facilitate air-guiding.
Design of exhaust system for UG mold design
2) The venting groove is generally designed on the side that is easy to process. When you make the parting surface, you should consider the processing of the venting groove
The left part of the sub-shaped pillow is concave, which is not conducive to the processing of the grinding machine. The picture on the right is designed as a bump for easy processing.
Design of exhaust system
General specifications for the parting surface exhaust groove Design of venting system for mold design
1) The width of the exhaust groove: 3.0mm
2) The width of the sealing surface is 10.0mm; the distance from the edge of the product to the exhaust groove is 2.0 mm; Peripheral sealing surface width 3.0MM
3) Make corresponding support surfaces around the parting surface. The width of the four corner tubes is 6.0MM
The length of the intermediate support surface is 20MM; the width 15MM: the distance between the middle is subject to the advance of the knife;
4) The length and width of the mold kernel takes 20 digits, the screw spacing “D takes” multiples of 20, the tube size 23MM
5) For the relationship between the exhaust groove and the exhaust groove, please refer to the following page:
Venting steel
The material of the venting steel is generally the same as that of the mold core material and is generally formed on a large flat surface of the male mold with thin glue and a weld line.
Other venting methods
For parting surfaces with a certain roughness, the gas can be discharged from the parting surface. In the middle position of the rubber parts, a thimble may be added, and the clearance between the thimble and the core may be used, or the gap between the thimbles may be intentionally increased to exhaust. For combined cavities and cores, they can be vented with their clearance.
