Selection principle

The basic principle for determining the three elements is to first determine the back feed according to the cutting requirements, then check the table to obtain the feed rate, and then calculate the main cutting speed through a formula after checking the table.

In many cases, we can determine the values of these three elements through empirical data.

Selection method

Practice has proven that the selection of reasonable cutting parameters is related to various factors such as machine tools, cutting tools, workpieces, and processes. The method for selecting processing dosage reasonably is as follows:

① During rough machining, the main goal is to ensure high production efficiency, so a larger back feed, larger feed rate, and a medium to low cutting speed U should be selected.

② During precision machining, the main requirement is to ensure the size and surface accuracy of the parts. Therefore, a smaller back feed, a smaller feed rate, and a higher cutting speed are selected.

③ During rough machining, it is generally necessary to fully utilize the potential of the machine tool and the cutting ability of the cutting tool. When semi precision machining and precision machining are carried out in CNC lathe factories, the focus should be on how to ensure machining quality and, on this basis, try to improve productivity as much as possible. When selecting the cutting amount, CNC lathe factories should ensure that the tool can process a part or ensure that the tool's durability is not less than one working shift, and at least not less than half a working shift. The specific values of the CNC lathe factory should be selected based on the provisions in the machine tool manual, tool durability, and practical experience.

Selection of back feed: The selection of back feed should be determined based on the stiffness of the machine tool, fixture, workpiece, and the power of the machine tool. If the process system allows, choose a larger back cut as much as possible. Except for the allowance left for future processes, the remaining rough machining allowance should be cut off as much as possible in one operation to minimize the number of tool passes.

Usually on medium power machine tools, the back feed for rough machining is 8-10 mm (single side). The CNC lathe factory has a semi precision machining back feed of 0.5-5 mm; The back cutting allowance during precision machining 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 precision turning in CNC lathe factories, it is advisable to choose a lower feed speed. The feed speed should be adapted to the spindle speed and back feed. During rough machining, the selection of feed rate is limited by the cutting force.