In many cases, we can use empirical data to determine the value of these three elements.

Selection method

Practice has proved that the selection of reasonable cutting parameters is related to many factors such as machine tool, cutting tool, workpiece and technology. The method of reasonable selection of processing amount is as follows:

  • ① In rough machining, it is necessary to ensure high production efficiency, so it is necessary to select larger back feed, larger feed rate and low cutting speed U.
  • ② When finishing, it is mainly to ensure the size and surface accuracy of the parts, so it is necessary to select smaller back feed, smaller feed and higher cutting speed.
  • ③ In rough machining, it is generally necessary to give full play to the potential of the machine tool and the cutting ability of the tool. In the process of semi finish machining and finish machining in CNC lathe factory, we should focus on how to ensure the machining quality and improve the productivity as much as possible. When selecting the cutting parameters, the CNC lathe factory should ensure that the cutting tool can complete a part or ensure that the durability of the cutting tool is not less than one working class, and less than half a working class. The specific value of CNC lathe factory should be selected according to the provisions in the machine tool manual, tool durability and practical experience.

The selection of back cutting amount: the selection of back cutting amount should be determined according to the rigidity of machine tool, fixture and workpiece, as well as the power of machine tool. In the case of the process system allows, as far as possible to choose a larger amount of back knife. In addition to the allowance left for the subsequent process, the rest of the rough machining allowance should be cut off as far as possible, so as to reduce the number of tool runs.

Generally, on medium power machine tools, the back draft of rough machining is 8 ~ 10 mm (one side). CNC lathe factory semi finishing back feed is 0.5 ~ 5 mm; finishing back feed is 0.2 ~ 1.5 mm.

Feed rate determination: when the quality requirements of the workpiece can be guaranteed, in order to improve productivity, higher feed rate can be selected. When cutting, turning deep hole or finishing lathe, the CNC lathe factory should choose a lower feed speed. The feed speed should be adapted to the spindle speed and back feed. In rough machining, the selection of feed rate is limited by cutting force.