The Importance of Feed Rate and Cutting Speed of CNC Machines

2022.9.30

There are two important parameters in the process of NC machine tool processing, namely feed rate and cutting speed. These two parameters affect the manufacturing efficiency of CNC machines, the quality of machined parts and the service life of tools in real time. Cutting speed measures power consumption and tool life. The feed rate controls the surface roughness and processing time of the finished product. This paper mainly introduces the importance of feed rate and cutting speed of CNC machines.


Parameters For CNC Machine

CNC machine processing is a kind of material reduction manufacturing process, which uses programming code to control the movement of tool axis. The programming code includes all necessary cutting parameters, such as tool movement, spindle speed and feed rate. These parameters must be considered when designing products for CNC machining operations.
These parameters will ensure the optimization of all parts of the CNC machining process. Tool life and power consumption will be optimized by cutting speed. The processing time and surface roughness of the finished product will be determined by the feed rate. Therefore, both the engineers and operators of CNC machines must understand the cutting speed and feed rate as well as their differences and how to obtain the cutting speed and feed rate.

 

Feed Rate and Cutting Speed of CNC Machines

In CNC machines, the feed rate is the speed at which the tool advances along the rotating workpiece, and the unit is usually the distance per spindle revolution. It can also be called the tool engagement speed, which is usually in inches/minute or millimeters/minute for milling operations. For boring and turning operations, measurements can be made in inches per revolution or millimeters per revolution.

 

The change of feed rate of CNC machines depends on the blank materials (steel, aluminum, stainless steel, etc.), tool materials (high-speed steel cutting tools, metal materials, etc.) and other cutting factors of the machined parts, such as surface finish and characteristics of CNC machines. The quality of processed products depends on the feed rate, so the optimization of feed rate is very important in the process of CNC machine processing.

 

The relative speed between the machining tool and the workpiece surface of CNC machines is generally called surface speed or cutting speed. It can also be defined as the linear distance (m/min or ft/min) that the cutting tool material moves on the workpiece surface during cutting. The main parameters of NC machine tools, such as power consumption, cutting temperature and tool life, are determined by cutting speed. The cutting speed value will vary according to different materials (such as high carbon steel, low carbon steel, aluminum and plastic). Some tools or processes, such as thread tools and knurling tools, will run at a cutting speed lower than the above speed.

 

The Importance of Feed Rate and Cutting Speed of CNC Machines

The feed rate and cutting speed of CNC machines are very important in their processing, because they determine the speed and quantity of materials to be removed, and affect the service life of machine tools. The difference between feed rate and cutting speed of CNC machines can be determined by the key factor called cutting temperature, because higher cutting temperature will affect the parameters such as tool life and surface roughness.

 

The inferior effects of speed and feed are not visible on softer materials (aluminum or resin) because there is enough error space. However, the inferior effects of speed and feed are visible on harder materials (titanium or Inconel) because of the limited error range. If there is a slight difference between speed and feed rate, the tool will break immediately. In order to obtain better surface roughness, speed and feed must be used. If the CNC machine runs at a higher tool speed and spindle speed, chatter marks will appear on the material surface.

 

The feed rate and cutting speed of CNC machines are different. Cutting speed is the speed at which the cutting tool passes through the material to be cut. Feed rate is the speed at which the material to be cut passes through the cutting tool. Engineers and machinists must consider the cutting speed and feed rate during the processing of CNC machines, because it directly affects the quality of finished products. If the cutting speed is too slow, the material will not be cut clean and there is a risk of burrs or other defects.

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