About the quality control of the preparation process of cemented carbide ball mixture
Carbide balls, commonly known as tungsten steel balls, refer to balls and balls made of cemented carbide. The production process mainly includes the preparation, forming, sintering, grinding and quality inspection of the mixture. The quality control of each process will have an impact on the final product performance and quality stability. Today, let's learn about the quality control of the cemented carbide ball mixture preparation process.
1. Raw material control
Regarding the raw materials of tungsten carbide balls, the purity of WC powder is generally required to be greater than 99.7%, and the content of harmful impurity elements such as Ca, Si, Al, Na, S and oxygen content is strictly controlled. Impurity elements will affect the wettability; if the oxygen content is too high, decarburization will occur during the sintering process of tungsten steel balls. The quality control of the binder phase mainly includes composition, structure and particle size. Generally speaking, different grades of cobalt powder with different particle sizes are used, that is, fine cobalt powder is used for fine WC powder, and coarse cobalt powder is used for coarse WC powder. Control the particle size, particle size distribution, oxygen content and carbon content of the raw material powder to remain stable.
2. Mixing process
The mixing process mainly includes wet grinding, drying and granulation. First, the hard phase and the binder phase are mixed by ball milling in a ball mill. After adding a forming agent (usually paraffin or rubber), the wet abrasive slurry is dried by vacuum drying, steam drying, etc., and then mixed after drying. The material is sifted and granulated. Alternatively, the drying and granulation of the mixture can be achieved at one time by spray granulation.
Common quality defects in the mixing process are mainly fouling and uneven carbide grain size. The sources of contamination mainly include equipment, tooling, forming agents and personnel, etc., which may lead to irremovable pores in the product after sintering, which directly affects the surface quality and performance of cemented carbide balls. Therefore, in the production process of tungsten steel balls, the operating procedures should be strictly followed, and the operator must wear hats, special gloves, etc.; the workshop equipment should be wiped frequently to reduce dust residue; the mixing process should ensure the uniformity of the mixing, especially the forming agent. Addition, if local crystalline particles are present, is highly volatile during sintering and leaves large pores. The grain size of carbide is mainly determined by the particle size and particle size composition of the original W powder, WC powder and WC in wet grinding, and is also affected by process conditions such as reduction, carbonization, and wet grinding. Coarse carbides are one of the fracture sources of alloys, which directly affect the fracture strength of cemented carbide balls. Therefore, the quality and selection of raw materials must be strictly controlled.
Carbide balls have high hardness, high wear resistance, good chemical stability and thermal stability, and are mainly used as valve balls in the petrochemical industry, balls for special bearings, balls for probes of testing instruments, balls for power tools and molds It is widely used in precision machinery, aerospace, military defense, petrochemical and other fields. If you want to purchase or customize products such as tungsten steel balls, choose a company with strict quality control. Zhuzhou Jinxin is a manufacturer of cemented carbide raw materials. It has set up a custom factory for processing non-standard cemented carbide parts. The material standards are implemented in accordance with the national GB/T18376.3-2001, and are higher than the industry standards. All products are qualified according to the enterprise standard inspection. It can only leave the factory and can provide material proof. It is a trustworthy enterprise.
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