WANLONG
The polishing principle is mainly reflected in two aspects: the principle of micro-particle grinding and the physicochemical principle.
1. Micro-particle Grinding:
When using abrasive particles for rough grinding, fine grinding, and polishing, the grinding marks on the stone surface become progressively finer until they are invisible to the naked eye. The surface becomes smooth, flat, and delicate. When the grinding depth reaches 110 micrometers, the processed surface exhibits a mirror-like luster and bright, vibrant colors.
Micro-grinding includes the following steps:
① Rough grinding: Requires a large cutting depth of the abrasive tool, high grinding efficiency, and relatively coarse grinding marks. The resulting surface is relatively rough. The main purpose is to remove the saw marks left by the previous process and grind the product to the required flatness and shape;
② Semi-fine grinding: Removes rough grinding marks and forms new, finer marks. The processed surface is flat and smooth;
③ Fine grinding: After fine grinding, the texture, particles, and color of the product are clearly displayed. The surface is delicate and smooth, and begins to show a slight luster;
④ Precision grinding: The processed product surface has no visible marks. The surface becomes increasingly smooth, with a gloss of approximately 40-50 degrees;
⑤ Polishing: The surface is bright and mirror-like, and the stone polishing machine can achieve a certain degree of mirror gloss (85 degrees or higher).
2. Physicochemical Principle:
The polishing process involves two methods: “dry polishing” and “wet polishing.” During these processes, physical-chemical interactions occur between the polishing abrasive and the stone product. Dry polishing involves raising the surface temperature of the stone to evaporate moisture, thereby increasing the concentration of the polishing abrasive and achieving an intensifying effect. This process brings the product’s gloss to the desired level, typically reaching 85 degrees or higher.
When polishing stones are applied to the workpiece and the surface becomes hot to the touch, water should be applied to the slab to cool it down. Continuous or excessive water application is not permitted, as the lubricating effect of water will prevent achieving the desired polishing results. Additionally, dry polishing alone should not be used exclusively, as excessively high temperatures can burn the slab surface and cause cracking.
Typically, after precision grinding, the product’s gloss level ranges between 40 and 50. However, some stone types fail to achieve this gloss level after precision grinding, such as Shanxi Black, Black Gold Sand, and Jining Black. These products typically achieve only 20–30 gloss units post-grinding. The aforementioned micro-particle grinding principle alone cannot fully explain this. For such materials, the polishing process intensifies during the “dry-wet” transition, temperature elevation, and cooling phases, triggering physicochemical reactions. Through successive “dry polishing” and “wet polishing” stages, the gloss gradually increases, ultimately exceeding 85 gloss units.
