The NC tool selection is based on a simple description of the selection factors of the machine tool.

2019-06-01 10:33:22

CNC machine tools have higher spindle speeds and larger spindle output power. Compared with traditional machining methods, they have stricter requirements on the machining tools used. They are strict in terms of precision, strength, rigidity and durability. The requirements also require dimensional stability, ease of installation and adjustment. These problems have imposed strict requirements on the structure of the tool, the standardization of geometric parameters, and serialization. For improving machining efficiency, CNC tools are a topic that cannot be avoided. Geometric shape, material state, fixture and machine tool selection rigidity have a decisive influence on tool selection. Therefore, for the choice of tools, the following is a brief introduction of what to consider.

The following aspects should be considered when selecting a tool:

1 Consider the cutting performance of the product material when selecting the tool. For example, when processing titanium alloys, high-strength steels, and stainless steel parts, Xiaobian recommends the selection of indexable carbide tools with good wear resistance.

2 Select the tool according to the machining stage of the part. For example, the roughing stage is the main purpose of removing the margin. Then we should choose large cutters with better rigidity and lower precision. In the semi-finishing and finishing stages, it is mainly to ensure the machining accuracy and product quality of the parts. Finishing tools with high durability and high precision should be used. If the rough and finishing tools are the same size, it is recommended to use the tools that have been eliminated during the finishing process, because the parts worn by the finishing process are mostly worn by the blade and the coating is slightly worn. It will affect the quality of the finishing process, but it will have little effect on the roughing with the main purpose of removing the allowance.

3 Select the tool and geometry parameters based on the characteristics of the area to be machined. When the parts are allowed to be processed, the tools with large diameter and long diameter ratio should be selected as much as possible. When processing thin-walled and ultra-thin wall parts, the end-cutting edge of the cutter should have sufficient centripetal angle to Reduce the cutting force of the tool and the cutting part. When processing soft materials such as aluminum and copper, an end mill with a slightly larger rake angle should be used. The number of teeth should not exceed 4 teeth.

When selecting the right tool, try to match the size of the tool to the surface size of the workpiece being machined. In actual production, for peripheral contour machining of flat parts, end mills are usually used; in milling planes, carbide milling cutters are preferred; in the processing of bosses and grooves, high-speed steel end mills are preferred; When milling the surface of the blank or roughing the hole, it is recommended to use a corn milling cutter with a carbide insert; for some three-dimensional and variable bevel contours, use ball-end milling cutters, ring milling cutters, tapered milling cutters and More disc cutters.

For free-form surface machining, because the cutting speed of the end of the ball-end tool is zero, in order to ensure the precision of the machining, the line spacing of the cutting will be small, so the ball-end milling cutter has a high degree of friendliness for surface finishing. The end mill has obvious advantages in terms of surface quality and processing efficiency compared to ball-end milling cutters. Therefore, when there is no overcut in the machining of parts, roughing and semi-finishing surfaces, try to choose end mills. . In addition, the durability and accuracy of the tool have a large impact on the tool price. In most cases, a good tool must increase the cost of the tool, but the processing quality and processing efficiency brought by the good tool can greatly reduce the processing cost of the entire product.

For the machining center, all the tools are pre-installed in the magazine, and the tool selection and tool change are performed by the NC program. Therefore, it is necessary to select the corresponding standard shank suitable for the tool system specification of the machine tool, so that the tool for CNC machining can be quickly and accurately mounted on the machine spindle or returned to the tool magazine. The programmer should have a good understanding of the structure size, adjustment method and adjustment range of the tool holder used in the machine tool to ensure that the radial and axial dimensions of the tool can be determined during programming, and the arrangement of the tools can be arranged more reasonably. order.