The basic principle to determine the three elements: first determine the back cut according to the cutting requirements, then look up the table to get the feed, and then calculate the main cutting speed through the formula after looking up the table.
On many occasions, we can determine the values of these three elements through empirical data.
Practice has proved that the selection of reasonable cutting parameters is related to many factors such as machine tools, cutting tools, workpieces and processes. The method to reasonably select the processing amount is as follows:
① During rough machining, it is mainly to ensure high production efficiency, so it is necessary to select a large back cut, a large feed rate, and a medium low cutting speed U.
② During finishing, it is mainly to ensure the size and surface accuracy of the parts. Therefore, smaller back cut, smaller feed and higher cutting speed are selected.
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. During semi finishing and finishing in CNC lathe factory, we should focus on how to ensure the processing quality and try to improve the productivity on this basis. When selecting the cutting parameters, the CNC lathe factory shall ensure that the tool can process a part or ensure that the tool durability is not less than one working shift, and at least not less than half of the working shift. The specific numerical value of CNC lathe factory shall be selected according to the provisions in the machine tool manual, tool durability and practical experience.
Selection of back cutting amount: The selection of back cutting amount shall be determined according to the rigidity of machine tool, fixture and workpiece and the power of machine tool. If the process system allows, select a larger back cut as much as possible. In addition to the allowance left for subsequent processes, the remaining rough machining allowance shall be cut off at one time as far as possible to minimize the number of tool passes.
Generally, on medium power machine tools, the back cut of rough machining is 8-10 mm (single side). The back cut of semi finishing in CNC lathe factory is 0.5~5 mm; The back cut during finishing is 0 2~1.5 mm.
Determination of feed rate: When the quality requirements of the workpiece can be guaranteed, a higher feed rate can be selected to improve productivity. When cutting, turning deep holes or finishing, CNC lathe plants should choose a lower feed speed. The feed speed shall be compatible with the spindle speed and back feed. In rough machining, the selection of feed rate is limited by the cutting force.