Material Selection

Raw materials are a critical factor in determining the performance of graphite sheets, graphite rods, and graphite products. Most raw materials are chemical-based, while a smaller number are directly sourced from mineral materials. Generally, these materials can be purchased directly from the market, but some, such as refractory compounds, are not easily available and must be synthesized in-house. The raw materials used for graphite sheets, rods, and products typically have a high purity, such as for the production of magnesia-carbon bricks, where magnesium oxide content should be equal to or greater than 95%, and flake graphite content should not be less than 92%. From a material performance perspective, it may seem that the purer the material, the better, but that is not necessarily true. In fact, everything is not about being too pure; for instance, if the impurity of iron(III) oxide in magnesia-carbon bricks is below 0.35%, it is sufficient to ensure the material's performance. Requiring an overly high purity would only increase the price.

2. Raw Material Heat Treatment

Raw materials used for manufacturing graphite plates, graphite rods, and graphite products, especially oxide-based materials, require heat treatment at certain temperatures prior to use. The methods, properties, and significance of heat treatment are as follows: (1) Sintering, which involves pre-burning the raw materials once at a temperature below the firing temperature of the product. (2) Electrical fusion, where the raw materials are introduced into an electric arc furnace for melting, then cooled and crushed into particles of various sizes, selected as needed. This process reduces the reactivity of the raw materials, thereby minimizing shrinkage during the firing of the green bodies and enabling control over their dimensions.

3. Crush

In the manufacturing of graphite boards, rods, and products, crushing is a critical process. Its task is to alter the particle size of the raw materials, providing various particle-sized powders for subsequent processes. The fineness of the raw materials significantly affects the molding, firing, and performance of the products. Overly coarse particle sizes reduce the plasticity of the mud material, increase the firing temperature, and result in a rough surface on the products.
4. Ingredients

Mixed various raw materials that have passed the processing qualifications in proportion, then added binder, preparing for the shaping of the green ware.

5. Green Body Shaping

The mixed and uniformly shaped material is further processed into坯体 of specified shape and size. With the continuous development of the molding process, an increasing number of molding methods have emerged: the commonly used molding method involves adding a certain amount of binder to the powder material and then forming it under pressure in a metal mold. Additionally, there are methods such as tamping, casting, extrusion, hot-pressure injection, film coating, isostatic pressing, hot pressing, casting, and chemical vapor deposition, among others.

6. Dry

After molding, the green body must be naturally dried in the air for a certain period before being placed in an oven or drying room for thorough drying to remove free moisture. Only then can the final firing be conducted. Alternatively, the molded green body can be directly transported to a tunnel kiln, where it is first dried at 1401°C before proceeding to the final firing.

7. Green Body Pre-Firing and Rough Machining

Prior to the final firing of the green body, a preliminary firing at a temperature below the firing point (known as biscuit firing) is conducted to remove various organic binders added to the green body, particularly the wax in bodies that are injection molded under heat. After the preliminary firing, the green body achieves sufficient mechanical strength, allowing for rough machining, such as dimension trimming, cutting, and drilling. Further mechanical processing becomes very difficult due to the increased hardness of the products after the final firing.

8. Burnt to a crisp

Sintering is a critical step in the manufacturing process for graphite plates, rods, and other graphite products. It is through sintering that the desired product is obtained. Mismanagement of this stage can result in wasted efforts.

9 Cold Processing and Inspection

Manufacturing processes for graphite plates, rods, and products are complex and involve numerous steps. Throughout these steps, factors such as raw material quality, process conditions, and technical operations can influence the final product, often resulting in discrepancies from the design specifications. Special equipment and tools are required for post-processing of the fired products to meet the required shape and dimensional tolerances. This processing is carried out in a cold state, hence referred to as cold working, which includes operations such as cutting, turning, planing, drilling, milling, grinding, and polishing. After processing, the products undergo rigorous quality inspection before they can be shipped.