When programming, it is important to select CNC milling tools correctly. The general requirements for CNC tools are easy installation and adjustment, good rigidity, high precision, and good durability. On this basis, the cutting performance of the workpiece material, the processing capacity of the machine tool, the type of CNC processing process, the cutting amount, and many factors related to the working range of the machine tool and CNC device are comprehensively considered.
Factors Affecting the Selection of CNC Cutting Tools
When selecting the type and specification of tools, the following factors should be considered.
Production Nature
Here, the production nature refers to the batch size of parts, and the impact on tool selection is mainly considered from the perspective of processing cost. For example, it may be cost-effective to use special tools in mass production. In single-piece or small-batch production, it is more appropriate to choose standard tools.
Machine Tool Type
The influence of the CNC machine tool used to complete the process on the selected tool type (drill bit, turning tool or milling cutter). Under the condition that the rigidity of the workpiece system and the tool system is good, high-productivity tools are allowed. For example, high-speed cutting turning tools and high-feed turning tools.
CNC Machining Plan
Different CNC machining plans can use different types of tools. For example, holes can be machined with drills and reamer drills, or with drills and boring tools.
Workpiece Size and Shape
The size and shape of the workpiece also affect the selection of tool type and specification. For example, special tools are used to machine special surfaces.
Processing Surface Roughness
The processing surface roughness affects the structural shape and cutting amount of the tool. For example, when rough milling a blank, a coarse-tooth milling cutter can be used, and when fine milling is performed, a fine-tooth milling cutter is preferably used.
Processing Accuracy
The processing accuracy affects the type and structural shape of the finishing tool. For example, the final processing of a hole can be processed by a drill bit , a reamer, a reamer or a boring tool according to the accuracy of the hole.
Workpiece Material
The workpiece material will determine the selection of tool material and geometric parameters of the cutting part. The tool material is related to the processing accuracy and material hardness of the workpiece.
Performance Requirements of CNC Cutting Tools
Due to the characteristics of high processing accuracy, high processing efficiency, concentrated processing procedures and fewer parts clamping times, higher requirements are placed on the CNC tools used. In terms of tool performance, CNC tools should be higher than those used by ordinary machine tools.
When selecting CNC tools, standard tools should be given priority first, and various high-efficiency composite tools and special special tools can be selected when necessary. When selecting standard CNC tools, various advanced tools should be selected as much as possible in combination with actual conditions, such as indexable tools, integral carbide tools, ceramic tools, etc.
When Selecting CNC Machine Tools, the Following Issues Should Also be Considered
The type, specification and accuracy level of CNC tools should be able to meet the processing requirements, and the tool material should be compatible with the workpiece material.
Good cutting performance. In order to adapt to the tool in rough processing or processing of workpieces of difficult-to-process materials, large back cutting amount and high feed rate can be used. The tool should have the performance to withstand high-speed cutting and strong cutting. At the same time, the same batch of tools must be stable in terms of cutting performance and tool life. In order to achieve tool change according to tool life or tool life management by the CNC system.
High precision. In order to meet the requirements of high precision and automatic tool change in CNC processing, the tool must have a high precision. For example, the radial dimension accuracy of some integral end mills is as high as
High reliability. To ensure that there will be no accidental damage to the tool and potential defects in CNC processing that affect the smooth progress of processing, the tool and its accessories must have good reliability and strong adaptability.
High durability. The tools used in CNC machining, whether in rough machining or fine machining, should have higher durability than those used in ordinary machine tool machining. This can minimize the number of tool replacement or grinding and tool setting, thereby improving the machining efficiency of CNC machine tools and ensuring machining quality.
Good chip breaking and chip removal performance. In CNC machining, chip breaking and chip removal cannot be handled manually in a timely manner like ordinary machine tool machining. Chips are easily entangled on the tool and the workpiece, which will damage the tool and scratch the machined surface of the workpiece, and even cause injuries and equipment accidents. This affects the machining quality and the safe operation of the machine tool, so the tool is required to have good chip breaking and chip removal performance.
Tool Selection Method
Tool selection is one of the important contents in CNC machining process, which not only affects the machining efficiency of machine tools, but also directly affects the machining quality of parts. Since the spindle speed and range of CNC machine tools are much higher than those of ordinary machine tools, and the spindle output power is relatively large. Therefore, compared with traditional machining methods, higher requirements are put forward for CNC machining tools, including high precision, high strength, good rigidity and high durability. And the size is stable and easy to install and adjust. This requires a reasonable structure, standardized geometric parameters and serialization of the tool. CNC tools are one of the prerequisites for improving machining efficiency. Its selection depends on the geometric shape of the machined parts, the material state, the fixture and the rigidity of the tool selected by the machine tool. The following aspects should be considered.
Choose tools according to the cutting performance of the part material. For example, when turning or milling high-strength steel, titanium alloy, and stainless steel parts, it is recommended to choose an indexable carbide end mill with good wear resistance.
Choose tools according to the machining stage of the part. That is, the rough machining stage is mainly to remove the excess. Tools with good rigidity and low precision should be selected, and the semi-finishing and finishing stages are mainly to ensure the machining accuracy and product quality of the parts. You should choose tools with high durability and high precision. The tools used in the roughing stage have the lowest precision, while the tools used in the finishing stage have the highest precision. If the same tool is used for roughing and finishing, it is recommended to use the tool eliminated from the finishing for roughing. Because the wear of the tools eliminated from the finishing is mostly slight wear on the blade, and the coating is worn and polished. Continued use will affect the quality of finishing, but the impact on roughing is small.
Choose tools and geometric parameters according to the characteristics of the processing area. If the part structure allows, tools with large diameter and small aspect ratio should be used. The end edge of the over-center milling cutter for cutting thin-walled and ultra-thin pendulum parts should have sufficient centripetal angle to reduce the cutting force of the tool and the cutting part. When processing parts made of softer materials such as aluminum and copper, you should choose an end mill with a slightly larger rake angle, and the number of teeth should not exceed 4.
