The manufacturing process of graphite electrodes is a complex and meticulous procedure involving multiple critical steps, each significantly influencing the quality and performance of the final product. Below are the key steps in the manufacturing process of graphite electrodes:
Raw Material Selection and Pretreatment:
- Raw Material Selection: The primary raw materials for graphite electrodes include petroleum coke, needle coke, and coal tar pitch. Petroleum coke, derived from the coking of petroleum residue and asphalt, possesses low ash content; needle coke, characterized by its fibrous texture and low coefficient of thermal expansion, is crucial for manufacturing high-power or ultra-high-power graphite electrodes; coal tar pitch serves as a binder.
- Pretreatment: The raw materials undergo calcination to eliminate moisture and volatile substances, enhancing their physicochemical properties. The calcination temperature is generally controlled between 1250-1350°C to ensure the raw materials meet high-quality standards.
Crushing, Grinding, and Screening:
The calcined raw materials are crushed, ground, and screened to obtain bone particles and powder with the desired particle size. This step is crucial for subsequent blending and mixing processes, ensuring uniformity and consistency of the raw materials.
Blending and Mixing:
- Blending: Based on product requirements, the selected raw materials are mixed in specific proportions to achieve the desired performance. Precise measurement and control during blending are essential to ensure consistent quality in the final product.
- Mixing: The blended raw materials are thoroughly mixed and kneaded to form a homogeneous mixture. Temperature and time are controlled during mixing to ensure proper blending and the desired plasticity of the raw materials.
Molding:
The kneaded material is pressed to form the preliminary shape of the graphite electrode. Precise control of pressure and temperature during molding is necessary to ensure the shape and dimensional accuracy of the product. Molding methods include die pressing, extrusion, and vibration molding, selected based on the product type and specifications.
Baking:
The molded graphite electrode undergoes high-temperature heat treatment to stabilize its structure. During baking, the coal tar pitch in the green body cokes, expelling volatiles while experiencing volume shrinkage and mass loss. The baked electrode exhibits significantly improved physicochemical properties, such as reduced bulk density, decreased electrical resistivity, and enhanced mechanical strength.
Impregnation (Optional):
For electrodes with high bulk density requirements, impregnation treatment is necessary. Impregnation aims to reduce the porosity of the product, increase its bulk density and mechanical strength, and improve its electrical and thermal conductivity. Parameters such as preheating temperature, vacuum time, asphalt injection temperature, and pressure are controlled during impregnation.
Graphitization:
The electrode is treated at even higher temperatures to transform the carbon material’s structure into a graphite crystal structure, enhancing its electrical conductivity and heat resistance. Temperature and time are controlled during graphitization to ensure the electrode reaches the desired graphitization degree. The graphitized electrode exhibits significantly reduced electrical resistivity and substantially improved conductivity.
Machining:
The graphitized electrode undergoes machining, including boring, turning, end-face finishing, thread milling, and steps such as cutting, end-face flattening, taper turning, and drilling for connectors. Strict control of machining accuracy and surface quality is necessary during machining to ensure the electrode’s dimensional accuracy and performance.
Inspection and Packaging:
The finished electrode undergoes comprehensive inspection, including parameters such as accuracy, weight, length, diameter, bulk density, electrical resistivity, and pre-assembly fit precision. After passing inspection, the electrode is packaged for transportation and storage.
Post time: Jul-14-2025