CNC Knowledge: Essential knowledge points about cutting tools in machining centers

1Basic classification of cutting tools

According to the end geometry, they are divided into flat bottom end mills, R angle flat bottom end mills, ball end mills and indexable embedded end mills.

2 Basic geometry of cutting tools

For cutting tools used for finishing, the cutting edges must have very good contour accuracy. Several possible tool contour deviations include:

① Accurate overview;

② Due to the imprecise grinding process, irregular chips are produced on the blade;

③ Radius deviation caused by inaccurate grinding process.

If the precision of the workpiece is very high, you should purchase a standard certified tool from the tool manufacturer.

Assuming that the maximum overhang length of the tool holder and tool system does not exceed the specified value, in order to ensure that the spindle can work accurately, the radial runout error of the tool should be detected at the tool holder and cutting edge respectively. If the radial runout error is too large, it will cause severe vibration of the spindle.

3How to choose the right cutting tool

1. Analyze the specific processing conditions, such as spindle and machine tool performance, tool clamping system and lubrication method, etc. ;

2. Analyze the material properties of the workpiece;

3. Analyze the processing surface quality, processing accuracy requirements, costs, etc. ;

4. Comprehensively consider various factors and make the optimal choice.

4 Methods for calculating high-speed cutting processing parameters

Three important formulas

5. Several important terms and processing parameters in high-speed cutting

(1) Cutting speed vc

vc refers to the appropriate cutting speed value suitable for high-speed processing of a certain workpiece material under the conditions of a specific tool. It refers to the linear speed of the tool.

How to correctly set the vc value of the cutting speed? Provided by tool suppliers; refer to existing experimental data; establish your own database through a large number of cutting experiments. The vc value provides an important basis for correctly setting other cutting parameters.

Effect of cutting speed on surface finish▼

Comparison of the color of iron shavings produced at different cutting speeds▼

(2) Effective diameter of the Deff tool

Effective tool diameter and calculation of effective tool diameter.

(3) Feed per blade fz

Definition of feed per edge.

How to correctly adjust the feed per edge of the tool? Supplied by cutting tool suppliers; refers to experimental data obtained by others through a large number of cutting experiments; Whether or not the edge feed is set correctly has an extremely important impact on the reasonable distribution of the cutting load on the tool.

(4) Axial and radial feed ap& ae

Calculation of axial feed

Depending on the spindle, tool and material, actual results will be affected.

The influence of ae and fz on softness▼

(5) Methods for calculating cutting parameters in high-speed machining

(6) Principles for defining processing parameters

In the high-speed machining process, the processing parameters need to be optimized and cannot be adjusted at will; the value of the cutting speed vc must be set correctly; the edge feed fz must be set correctly.

A reasonable value can maximize the cutting performance of the tool to the limit, make full use of the tool, and improve the quality and processing efficiency. This will not affect tool life, thereby reducing costs and enabling true high-speed machining;