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GRP tile is a new type of composite material, composed of glass fiber and resin. It not only has the high strength, hardness and transparency of glass, but also has some advantages of plastic, such as...
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BMC insulation is a thermoset composite material consisting of staple fiber reinforcements, fillers, resins, and additives. These components are blended to form a flowable mixture that can be processe...
With the rapid development of the industry, many products use BMC products, such as some parts, medical equipment, household appliances, etc. will use it. However, when the injection molded product is put into production, the brightness of its surface will affect the appearance of the product, so it is very important to improve the brightness of BMC injection molded products.
1. The key elements in the molding process of BMC products
In the molding process of BMC molded products, the three important factors are pressure, temperature and time, all of which are indispensable. Generally, a hydraulic press and an oil temperature machine are required to be used together. When the molding temperature and molding pressure are constant, the molding time becomes the key factor to determine the performance of BMC molding products. Appropriate preheating conditions can speed up the heating process of the material in the cavity and the process of filling the cavity, so it is beneficial to shorten the molding time. When the molding temperature is increased, the molding time is shortened and the thickness of the product wall is increased, and the molding time is correspondingly extended.
The molding temperature is controlled in stages. From the preheating and complete closing of the mold, until the product is formed, and the mold is opened, it is necessary to use an oil temperature machine to control the temperature. The temperature and time of this stage are determined according to different products, so the BMC molding temperature and time are basically controlled by the oil temperature machine. The molding temperature and time of BMC products are mainly to allow enough time for the molding to obtain the shape of the cavity to complete the curing. Molding temperature and time determine the cure rate of the BMC stock, as well as the shape and wall thickness of the article. Although these are related to the structure of the mold and many factors such as pre-pressing, preheating and whether to exhaust during molding, among these factors, the influence of molding temperature and molding time is more significant.
If the molding time is too short, the resin will not be fully cured, and the BMC molding product will be under-matured, resulting in poor mechanical properties, lack of luster in appearance, and warping and deformation after demolding. Properly extending the molding time can not only overcome the above shortcomings, but also reduce the molding shrinkage of the product and improve its heat resistance, strength properties and electrical insulation properties.
2. How to improve the brightness of BMC products
The injection mold can directly affect the brightness of the product. For example, the mold release slope is too small, the exhaust is not good, the surface is stained, the gate area is too small, and the mold processing is not good enough, etc., which can directly affect the brightness of the product. If the demolding slope of the mold is too small, the friction between the product and the mold will increase, which will lead to difficulty in demolding and affect the gloss of the product surface. This also directly affects its appearance.
If the mold itself is worn, not smooth or scratched, the BMC mold product will also have a corresponding situation. If the mold has many stains, the surface of the injection molded product will become very dark. Therefore, increasing the demolding slope, ensuring the normal exhaust of the mold, and maintaining the cleanliness and integrity of the mold will effectively improve the brightness of the injection molded products. Another reason that affects its brightness is that there are problems in the injection molding process. If the product cannot be fully cooled during the injection molding process, the brightness of its surface will be very dark, so the better the cooling system, the higher the brightness of the product. During smelting, if the temperature is too low, the fluidity of the BMC injection molding product production process will become poor, and the gloss of the product will not be good enough, so the temperature of the melt needs to be increased. As long as you master the skills, you can make better and more beautiful products.
