cutting

Selection of cutting tools in NC machining

CNC machine tools are very common in pump production workshops, and cutting tools are related to the accuracy of processing workpieces and determining the quality of products. Today, I’d like to talk about the matters needing attention in the selection of cutting tools.

When selecting the type and specification of cutting tools, the following factors are mainly considered:

(1) Nature of production

Here, the production nature refers to the batch size of parts, mainly considering the impact on tool selection from the perspective of processing cost.

For example, it may be cost-effective to use special tools in mass production, while it is more suitable to choose standard tools in single piece or small batch production.

(2) Machine type

The influence of the NC machine tool used to complete the process on the selected tool type (drilling, turning or milling). Under the condition that the rigidity of workpiece system and tool system can be guaranteed, high productivity tools, such as high-speed cutting turning tools and large feed turning tools, are allowed.

(3) CNC grinding service

Different types of cutting tools can be used in different NC machining schemes. For example, the hole can be processed with drill and reamer, or with drill and boring cutter.

(4) Dimension and shape of workpiece

The size and shape of the workpiece also affect the selection of tool type and specification. For example, special tools should be used to process the special surface.

(5) Machined surface roughness

The machined surface roughness affects the structural shape and cutting parameters of the tool. For example, during rough milling, coarse tooth milling cutter can be used, and fine tooth milling cutter is best used during finish milling.

(6) Machining accuracy

Machining accuracy affects the type and structural shape of finishing tools. For example, the final machining of holes can be processed by drilling, reaming drilling, reamer or boring cutter according to the accuracy of holes.

(7) Workpiece material

The workpiece material will determine the choice of tool material and geometric parameters of cutting part. The tool material is related to the machining accuracy and material hardness of the workpiece.

Because the NC machine tool has the characteristics of high machining precision, high machining efficiency, centralized machining processes and less parts clamping times, higher requirements are put forward for the NC cutting tools used. In terms of tool performance, NC tools should be higher than those used by ordinary machine tools.

When selecting NC tools, we should first give priority to standard tools, and select various high-efficiency composite tools and special tools when necessary. When selecting standard NC tools, various advanced tools should be selected as far as possible in combination with the actual situation, such as indexable tools, integral cemented carbide tools, ceramic tools, etc.

When selecting NC machine tools, the following aspects should also be considered:

(1) The type, specification and accuracy grade of NC cutting tools shall meet the processing requirements, and the cutting tool material shall adapt to the workpiece material.

(2) Good cutting performance. In order to adapt to the large back feed and high feed when the tool is used for rough machining or machining workpieces with difficult machining materials, the tool should be able to withstand high-speed cutting and strong cutting. At the same time, the cutting performance and tool life of the same batch of tools must be stable in order to change tools according to tool life or manage tool life by NC system.

(3) High precision. In order to meet the requirements of high precision of NC machining and automatic tool change, the tool must have high precision. For example, the radial dimension accuracy of some integral end mills is as high as 0.005mm.

(4) High reliability. In order to ensure that accidental damage and potential defects of tools will not occur in NC machining, which will affect the smooth progress of machining, the tools and their combined accessories must have good reliability and strong adaptability.

(5) High durability. NC machining tools, whether in rough machining or finish machining, should have higher durability than those used in ordinary machine tools, so as to minimize the number of tool replacement or grinding and tool setting, so as to improve the machining efficiency of NC machine tools and ensure the machining quality.

(6) Good chip breaking and chip removal performance. In NC machining, chip breaking and chip removal can not be handled manually in time like ordinary machine tool machining. Chips are easy to wrap around the tool and workpiece, which will damage the tool and scratch the machined surface of the workpiece, and even hurt people and equipment accidents, affecting the machining quality and the safe operation of the machine tool. Therefore, the tool is required to have good chip breaking and chip removal performance.

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Christophe Rude

Christophe Rude

Articles: 15889

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