Shanxi Black Stone is a high-quality black stone known for its hardness and corrosion resistance. The ultra-thin slabs, also known as centimeter boards, have poor bending and are particularly brittle. During the fire surface processing, they can heat up, bend, and arch, leading to cracking and a high rate of damage. Additionally, the surface bending often does not return to its original straightness. Ultra-thin slabs are generally for export, and the quality standards are particularly stringent.
1. Small-scale board (Circular Saws) stone thickness is less than or equal to 15mm.
2. Large-scale slabs (sand sawn) have a thickness less than 20mm or equal to 20mm.
Shanxi Black Stone Ultra-thin Plate Processing: Precautions to Take
One, select the front and back sides
Why so? The thick face burn has better flatness, won't arch in the middle when cut, but it burns slowly and is prone to cracking after prolonged heating, which also increases the material cost of the burn and reduces efficiency. I believe that based on the principle of minimizing cracked boards, good-burnt stone should be set with a thick face burn, while difficult-to-burn stone should be cut with a burn machine face.
Prevention First
Problems often arise when the project is nearly complete, and it's often too late to make amends. Therefore, we should continuously inspect the finished products for cracks as soon as they are completed or during the process. The workers' skills are not the issue; it's their mindset. The inspection method is simple: stand the fired boards upright, sprinkle some water on the back of the fire-side, ensuring not to get water on the fire-side itself. After waiting a few minutes, if there are watermarks, it indicates that the board has cracks. Then identify the problem, whether it's an issue with the stones, improper heat, or techniques.
Strategically dissipate heat
Overcoming the bottleneck of cracking in ultra-thin plates involves dispersing the heat on the sheets as much as possible. When firing, stack multiple sheets instead of a single one, and use a staggered firing pattern, pulling a line (this is also true in normal cases, though some stones may not be suitable for this method). It's crucial to first fire the ends before the middle to ensure heat dissipation, especially for difficult-to-fire stones. Otherwise, the ends might burn well, but the middle will not.
IV. Proper Laying Technique
Before lighting the fire, find a wooden frame and place a thick board at the bottom first. Clean the area thoroughly before laying down the ultra-thin board for burning. After burning, the fire-side should be placed face-to-face to force the boards to straighten, but do not place too many.
V. Tool Selection
Nowadays, most welders use large-sized welding torches, which have strong power, rapid speed, large flames, and consume gas excessively. Small-sized welding torches have less power, burn slowly, and struggle to melt hard stones. The ideal tool is a modified large cutting torch, which burns cleanly and has a large flame as well. However, if not used to it, gas consumption is also significant.
Six: Boil in a pond
If the method is to burn Shanxi black stone slabs, which are one centimeter thick and crack upon burning, it involves adhering a stone basin and filling it with water. Place a flat base in each corner of the basin, then insert the to-be-burnt slabs. Ensure the top surface is above the water level; if it gets wet, the burning process will slow down, so it should not be submerged. If possible, use recirculating water to lower the water temperature.
Seven: Precautions for sand saw ultra-thin plates
The fire-burning technique for sand saw ultra-thin plates is more challenging than for smaller-sized plates. To minimize cracking in the ultra-thin plates, they must be burned upright and not flat on the ground. However, burning them standing is difficult for most people and often not done well. The same principle applies: burn the edges first, then the center, spacing the jumps further apart, and the joints should have a tooth-like appearance. The flame should be smaller and not too intense. When placing the plates, ensure that all four corners are snug against each other, otherwise, they may also crack.
Above is an introduction to the precautions in the processing of ultra-thin black marble slabs in Shanxi. Those interested in purchasing Shanxi black marble can inquire with Ling Shou Han Teng Stone Factory.
