The production process of rotary files

Most domestic manufacturers, and even some foreign manufacturers, use the carbide blank brazing process with tail hole. Although the cemented carbide rotary file made by this process is cheaper because it can save a part of the cemented carbide raw materials, and the copper welding consumables are the cheapest. But most of the cemented carbide rotary files produced in this way are of poor quality and very unstable, because there are two key problems in such a process, one is welding temperature, and the other is the control of welding stress.

First of all, the cemented carbide rotary file adopts sandwich silver welding material, the temperature required for sandwich silver welding material is about 800 °C, and the temperature required for copper brazing material is about 1100 °C. According to relevant research reports and our experience, when the temperature exceeds about 900 °C, the surface of cemented carbide begins to oxidize rapidly, the cobalt in cemented carbide burrs begins to liquefy, and the metallographic structure inside cemented carbide begins to change. Therefore, in the copper brazing process, the properties of cemented carbide will be damaged to a certain extent, but in the sandwich silver welding process, its welding temperature is relatively low, and the damage to the properties of cemented carbide is very limited. Then the design of the interlayer silver solder lug, its two ends are silver, the middle sandwich is copper alloy, this welding material can significantly reduce the welding stress, low welding stress will not cause cemented carbide microcrack defects, at the same time, its welding strength is much better. Finally, we use automatic welding machine is also a very important factor, in the automatic welding process, carbide head and steel handle are automatic butt brazing, do not need manual participation, greatly ensure the stability of welding quality, and after welding, steel shank and carbide head between excellent coaxiality.