2021.4.26
Tool setting in CNC machining is an important skill and main operation. The machining accuracy of parts depends on the accuracy of tool setting. In addition, the efficiency of tool setting will also affect the efficiency of CNC machining. So it is important to be familiar with the types of CNC machining. This guide covers top 7 tool setting methods of CNC machining.
Tool setting in CNC machining is to establish the workpiece coordinate system, that is to determine the position of the workpiece in the machine tool workbench. To put it simply, it is to find the coordinate of the tool setting point in the machine tool coordinate system. The tool setting point in CNC machining refers to the starting point of the tool movement relative to the workpiece. CNC machining tool setting point can be set on the workpiece, can also be set on the CNC machine tool or fixture. If it is set at a certain point on the fixture or CNC machine tool, the point must maintain a certain precision dimensional relationship with the positioning datum of the workpiece.
In tool setting, the tool location should coincide with the tool setting point. The tool location refers to the positioning reference point of the tool. For turning tools, the tool location is the tool tip. CNC machining tool setting is to determine the absolute coordinate value of tool setting point in the machine coordinate system and measure the tool position deviation value. The accuracy of tool point alignment will affect the machining accuracy. In the actual processing of workpiece, one tool often can not meet the needs of processing, so multiple tools are needed at the same time. When using multiple tools, the geometric position of the tool tip will be different when the tool change position is unchanged, which requires different tools to start processing at different starting positions to ensure the normal operation of the program. The CNC machine tool system is equipped with the function of tool geometric position compensation. By using the function of tool geometric position compensation, as long as the position deviation of each tool relative to a pre selected reference tool is measured and input into the CNC system.
In the group number specified in the tool parameter correction column, the tool position deviation can be automatically compensated in the tool path by using t instruction in the machining program. The measurement of tool position deviation also needs tool setting operation.
The basic methods of tool setting in CNC machining include trial cutting method, tool setting instrument and automatic tool setting. Now take a look at below common ways of CNC tool setting.
1. Trial cutting and knife alignment
This CNC tool setting method will leave cutting traces on the surface of the workpiece, and the tool setting accuracy is relatively low, but this method is simple and convenient.
2. Tool alignment of feeler gauge, standard mandrel and block gauge
This CNC tool setting method does not rotate the spindle during tool setting, which is similar to the trial cutting tool setting method. A feeler gauge is set between the tool and the workpiece, and the feeler gauge can’t move freely. When calculating the coordinates, the thickness of the feeler gauge should be subtracted. The spindle does not need to rotate to cut, this tool setting method will not leave traces on the surface of the workpiece, but the accuracy is not high enough.
3. Tool alignment with edge finder, eccentric bar and shaft setter
It is similar to the trial cutting method, except that the tool is replaced by an edge finder or an eccentric bar. This method is very common and has high accuracy and efficiency. However, when using the edge finder, care should be taken to make the steel ball part slightly contact with the workpiece. At the same time, the workpiece to be processed must be a good conductor, and the positioning reference surface has a good surface roughness. Z-axis setter is generally used to transfer (indirect) tool alignment.
4. Transfer (indirect) knife alignment
CNC machining a workpiece can not only use one tool, the length of the second tool is inconsistent with the length of the first tool, so it is necessary to re zero, sometimes the zero point will be processed out and can not be directly recovered, it is not allowed to damage the machined surface, some tools or occasions can not be directly set, then indirect zero method can be used.
5. Tool alignment with special tool aligner
The traditional method of tool setting in CNC machining has poor security, takes up many opportunities and large random error, which can not adapt to the rhythm of CNC machining and is not conducive to the function of CNC machine tool. Using the special tool setting device, the tool setting accuracy is high efficient and safe, which simplifies the work and ensures the high efficiency and high accuracy of CNC machine tools. It has become an indispensable special tool to solve the problem of tool setting in CNC machining.
Other tool setting methods for CNC machining: Tool alignment of dial indicator, the top of the knife.
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