At present, the grinding burn detection methods generally adopted by enterprises are as follows:
1. The visual method, also known as the visual method. When there is grinding burn on the surface of the part, an oxide film will be formed, and the color and thickness of the oxide film are related to the degree of burn. As the temperature of the part increases due to the cutting heat, no matter whether the material of the part is cast iron or steel, the color of the oxide film is yellow, brown, purple, cyan, and gray in the worst case. Therefore, the inspector can make a rough judgment on the degree of burn only by carefully observing and identifying the color of the grinding surface of the part.
2. Pickling method, also known as acid etching method. That is, coat the surface of the inspected parts with acid solution or immerse them in a tank containing acid solution prepared according to regulations (typically, the ratio is 5mL concentrated nitric acid and 100mL ethanol). According to the change of the color depth on the surface of the part, make a corresponding judgment on the degree of grinding burn. In general, as the surface of the part becomes darker and darker, the grinding burn caused by the increase in temperature is more serious.
3. Metallographic testing method. The metallographic structure of the parts is detected by a metallographic microscope, and then the degree of burns is judged.
4. Hardness test method. When grinding burn occurs, the surface hardness of the workpiece decreases, so it can be verified by hardness testing.
Among the above methods, although the first two are intuitive and easy to implement, they have great limitations, mainly because both of them are qualitative inspections, which cannot quantitatively explain the degree of burns, and it is more difficult to determine the boundaries more accurately. , to distinguish whether the parts are qualified or not. When the pickling method is applied, the surface of the workpiece is etched by acid solution, and even if it is a non-problematic part, it cannot be used again. It is actually a destructive inspection, and it will also bring some environmental protection to the enterprise question. Although metallographic testing is relatively accurate, special instruments must be used in the laboratory, and complex sample preparation is required before testing, so it cannot be used as a routine monitoring method.
To sum up, with the increasing attention and emphasis on product manufacturing quality, enterprises are looking forward to a practical detection method that can quickly and effectively quantitatively judge the degree of wear and burn of grinding parts.
