1. Injection temperature: Including the barrel temperature (which can be divided into three sections: back, middle and front), nozzle temperature and mold temperature. Although ABS melt viscosity is less affected by temperature than injection pressure, it is advantageous for thin-walled Silicon Carbide Ceramics molds under high temperature conditions. The decomposition temperature of ABS is theoretically as high as 270t. Above, but in the actual injection molding process, due to the influence of time and other process conditions, the resin often begins to change color at around 2501, and the rubber phase contained in ABS does not adapt to too high temperature, otherwise it will affect the product performance . The molding temperature of ABS requires a slightly higher temperature (at 210-250°C) for resins such as heat-resistance and electroplating grades in order to improve the difficulty of filling the melt or benefit the electroplating performance. For general-purpose, flame-retardant The temperature of ABS resin such as grade and impact grade should be lower to prevent decomposition or unfavorable physical and mechanical properties. The temperature of the plug type injection machine is slightly higher than that of the screw type injection machine. For general products, the temperature range of the plunger type selection is between 180~230℃, while the screw type injection machine is 160~220X: it can be molded . In the molding process, the general barrel temperature (150~1701℃ in the rear, 170~180℃ in the middle, 180~210℃ in the front) The temperature of the nozzle is generally 170~180°C. Special attention should be paid to any changes in the temperature of the homogenization section and the nozzle, which will be reflected on the product, causing flashing, silver wire, discoloration, poor gloss, and obvious weld marks.
2. Mold temperature: Mold temperature has an important effect on the surface roughness of ABS products and reduce the internal stress of the products. The mold temperature is high, the melt is easy to fill the mold, the appearance of the product is good, the internal stress is small, and the electroplatability of the product is also improved or improved, but there are also large product shrinkage rates, long molding cycles, and easy demolding. Variations and other issues. For products with general requirements, the mold temperature can be controlled at 40~50°C; for products with high appearance and performance requirements, the mold temperature can be controlled at 60~70°C. Moreover, the mold temperature must be uniform, and the temperature difference between the mold cavity and the mold core should not exceed 10. For deep-hole products or products with more complex shapes, the mold cavity temperature is required to be slightly higher than the mold core temperature to facilitate Silicon Carbide Ceramics the smooth release of the product. mold.
3. Injection pressure: Compared with polyethylene, polystyrene, nylon and other plastics, the fluidity of ABS is slightly worse, so the required injection pressure is higher. However, excessive injection pressure is likely to cause difficulty in demoulding or damage to the product, and may also bring greater internal stress to the product. The injection pressure of ABS is not only related to the wall thickness of the product and the type of equipment, but also related to the grade of the resin. For thin-walled, long-flow, and small-gate products, the required injection pressure should be high, as high as 130~150MPa, while thick-walled and large-gate products only need 100MPa. In the actual production process, the injection pressure of the screw injection machine is usually below 100MPa, (we use 50~70MPa), and the plunger injection machine is generally above 100MPa. The holding pressure should not be too high. The screw injection machine generally uses 30-50MPa, while the plunger type requires 60-70MPa or more. If the holding pressure is too high, the internal stress of the product will increase.
4. Injection speed. The injection speed has a certain effect on the change of the fluidity of the ABS culture body. If the injection speed is slow, the appearance of the product will appear ripples, poor welding, etc.; if the injection speed is fast, the mold can be filled quickly, but poor exhaust is likely to occur. Poor apparent roughness, etc., will also reduce the tensile strength and elongation of the product, and the adhesion of the coating will also decrease due to the excessively fast injection speed. For this reason, in the production process, in addition to the difficulty of filling the mold, a higher injection speed must be used. Generally, medium and low continuous degrees are appropriate.
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2020 12/29