Preparations for BMC Material Products Before Compression Molding

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1. Overview of BMC materials and DMC materials

In fact, the main components of BMC and DMC are the same, but the names are different in different industries and regions. The United Kingdom is the first country to adopt the DMC abbreviation, and DMC is more popular in Europe. On the contrary, the BMC abbreviation is more popular in the United States. , according to the definition of American SPI; BMC material is chemically thickened DMC, which also shows that DMC material has a long history. DMC abbreviation is still relatively well-recognized in China, especially in the electrical appliance industry, but now the international development tends to BMC abbreviation. BMC abbreviation is used more frequently than DMC.

2. Preparations for BMC material products before pressing

The BMC material used as a wet premix contains volatile active monomers, so do not remove its package prematurely before use, otherwise, these active monomers will volatilize from the BMC material, reducing the fluidity of the material, and even cause performance degradation and scrapping. At the same time, for the materials that have been unpacked but not used up, they need to be re-sealed and packaged for the next pressing.

Usually, before use, it is necessary to determine the appropriate feeding amount according to the actual situation, and at this time, it is necessary to calculate and weigh first. The first is to know the volume and density of the pressed product, plus the loss of burrs, flashes, etc., and then calculate the amount of feed. The accurate calculation of the charging amount has a very direct relationship to ensuring the accuracy of the geometric dimensions of the product, preventing material shortage or waste and material waste caused by excessive material.

At the same time, this is a good way to save materials and reduce costs for some production operations. Secondly, before the operation, the mold needs to be preheated. In fact, BMC material is a kind of thermosetting reinforced plastic. For thermosetting plastics, the mold should be preheated to the required temperature before molding. This actual temperature is related to the type, formula, The shape and wall thickness of the product, the molding equipment used and the operating environment are all related.

At the same time, it should be noted that in order to improve the strength and quality of BMC material products, it is often necessary to install inserts in the products. When inserts need to be set, the inserts used should be placed in the cavity before charging and pressing. The insert should meet the design requirements, and if it is a metal insert, it needs to be cleaned before use. For larger metal inserts, they also need to be heated and preheated before placement to prevent defects such as cracks due to too much shrinkage difference between the material and the metal.

In addition, you must be cautious when loading the mold, because in the pressing and molding of BMC materials, whether the molding operation is proper and reasonable will not only affect the flow of the material in the mold cavity during pressing, but also affect the to the quality of the product.