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The design of the venting groove in the Syringe Moul […]
Insufficient filling often occurs in the production of syringe core molds. Compressed air burns, high internal stresses inside the product, surface flow lines and fusion lines. In addition to these phenomena, in addition to the first adjustment of the injection molding process, it is also necessary to consider whether the mold gate is reasonable. When both the injection molding process and the gate are eliminated, the exhaust of the mold is the main problem. The main means to solve this problem is to open the exhaust vent.
1 The role and design of the nozzle of the syringe core mold
1.1 The role of the syringe core mold venting groove
There are two main functions of the syringe core mold venting groove.
First, when the molten material is injected, the air in the cavity is excluded;
The second is to exclude various gases generated during the heating process. The thinner the wall product, the farther away from the gate, the opening of the venting groove is particularly important. In addition, attention should be paid to the opening of the venting groove for small parts or precision parts, because it can avoid the surface burn of the product and the insufficient injection volume, and can also eliminate various defects of the product and reduce mold contamination. So, how is the exhaust of the cavity sufficient? In general, if the melt is injected at the highest injection rate without leaving a focal spot on the article, it can be considered that the exhaust in the cavity is sufficient.
1.2 Syringe core rod mold exhaust method
There are many methods for exhausting the mold cavity of the syringe core mold, but each method must ensure that the exhaust groove is designed to prevent the material from overflowing into the groove while the exhaust gas is being exhausted; secondly, it is also prevented from being blocked. Therefore, from the inner surface of the cavity to the outer edge of the cavity, the length of the groove of 6~12mm or more should be about 0.25-0.4mm. In addition, too many exhaust vents are harmful. This is because if the clamping pressure applied to the portion of the cavity part that is not opened is large, it is easy to cause cold flow or cracking of the cavity material, which is very dangerous. In addition to venting the cavity on the parting surface, it is also possible to achieve the purpose of venting by providing a venting groove at the end of the flow of the casting system and leaving a gap around the ejector pin. Because of the depth, width and position of the venting groove; if not, the resulting flash burrs will affect the aesthetics and precision of the product. Therefore, the above gap is limited in size to prevent flashing around the ejector rod. Special attention should be paid here to the fact that parts such as gears may be undesirably even the smallest flashes when venting. This type of part is best vented in the following ways:
1 thoroughly remove the gas in the flow channel;
2 The blasting treatment was carried out on the surface of the parting surface with a silicon carbide abrasive having a particle size of 200#. In addition, the opening of the venting groove at the end of the pouring system flow mainly refers to the venting groove at the end position of the branching passage, and the width thereof should be equal to the width of the dividing passage, and the height varies depending on the material.
1.3 syringe core mold design method
Based on years of experience in syringe core mold design and product trial testing; we briefly introduce the design of several exhaust slots. For product molds with complex geometries, the opening of the venting groove; it is best to determine it after several trials. The biggest shortcoming of the overall structural form of the mold structure design is poor exhaust. There are several exhaust methods for the integral cavity core:
1 using the groove or insert of the cavity to be part of the person;
2 using side insert seams;
3 partially made spiral shape
4. Mounting the grooved slat heart opening process hole in the longitudinal position;
5 When the exhaust is extremely difficult, the insert structure is used. If some die's dead angle is not easy to open the exhaust groove, the mold should be appropriately changed into the insert without affecting the appearance and precision of the product, which is not only beneficial for processing. Exhaust gas can sometimes improve the original processing difficulty and facilitate maintenance.
Shengjiu Mould Co , Ltd is one of the leaders in disposable medical equipment in the mold industry. Specializing in the manufacture and supply of high quality syringe molds in China, product details visit: http://www.medicalmould.net