The terms “CNC feed rate” and “cutting speed” are two of the most important parameters when machining a workpiece on a CNC (Computer Numerical Control) machine. While they are related, they are not the same and understanding the differences between them is critical for successful and efficient machining.
What is CNC Feed Rate?
The CNC feed rate is the speed at which the cutting tool moves over the surface of the workpiece to cut the material. In other words, it is the rate at which the tool is fed into the workpiece. The feed rate is typically expressed in units of length per minute, such as inches per minute (IPM). The feed rate can also be expressed as a ratio between the cutting speed and the feed rate. For example, a ratio of 4:1 would mean that the tool is fed into the workpiece at four times the speed of the cutting speed.
CNC Cutting Speed
The cutting speed, on the other hand, is the speed at which the cutting tool rotates. This is usually expressed in terms of revolutions per minute (RPM). The cutting speed is determined by the material being machined and the type of tool being used. For example, a high-speed steel (HSS) tool will typically require a higher cutting speed than a carbide tool.
Relation of Feed Rate and Cutting Speed
The relationship between the CNC feed rate and the cutting speed is a balancing act. The feed rate needs to be high enough to efficiently remove material, but low enough to avoid excessive wear on the tool. The cutting speed needs to be slow enough to avoid excessive heat buildup and tool breakage, but fast enough to achieve an acceptable finish. The optimal balance of feed rate and cutting speed will depend on the material being machined, the type of tool being used, and the desired finish.
When setting up the CNC machine, the operator will need to consider both the feed rate and the cutting speed.
Generally speaking, the feed rate should be set to a value that is slightly slower than the cutting speed.
This will ensure that the tool does not cut too deeply into the workpiece and helps to extend the life of the tool. It also helps to reduce the amount of heat generated during the machining process.
Conclusion
The feed rate and the cutting speed both play an important role in the machining process. It is important to understand the differences between the two, and to set them up properly in order to achieve optimal results. By understanding the relationship between the two, and setting them up properly, the machining process can be optimized for maximum efficiency and profitability.
