The tool is hard, but as the use time is delayed, the tool will also wear to a certain extent. What are the causes that affect tool wear? Several reasons were summarized.

1. Tool materials

CNC tool material is the fundamental factor that determines the cutting performance of the tool, and has a great impact on processing efficiency, processing quality, 

processing cost and tool durability. The harder the tool material, the better its wear resistance, the higher the hardness, the lower the impact toughness, and the brittle the 

material. Hardness and toughness are a pair of contradictions, and it is also a key factor that tool materials should overcome. For graphite tools, for ordinary TiAlN coatings, 

you can choose materials with relatively better toughness, that is, with a slightly higher cobalt content; for diamond-coated graphite tools, you can choose materials with 

relatively better hardness. , that is, the cobalt content is slightly lower;

2. The geometric angle of the tool

Choosing the appropriate geometric angle of the graphite tool will help reduce the vibration of the tool. In turn, the graphite workpiece will not be easily chipped;

1. Rake angle. When using a negative rake angle to process graphite, the tool edge has better strength and good impact and friction resistance. As the absolute value of the 

negative rake angle decreases, the wear area of the flank face does not change much, but overall It shows a decreasing trend. When using positive rake angle machining, as 

the rake angle increases, the strength of the tool edge is weakened, which in turn leads to increased flank wear. When machining with a negative rake angle, the cutting 

resistance is large and the cutting vibration is increased. When machining with a large positive rake angle, the tool wear is serious and the cutting vibration is also large.

2. Relief angle. If the relief angle increases, the strength of the tool edge decreases and the wear area of the flank surface gradually increases. When the tool clearance angle 

is too large, the cutting vibration is enhanced.

3. Helix angle. When the helix angle is small, the blade length of the same cutting edge that cuts into the graphite workpiece at the same time is the longest, the cutting 

resistance is the largest, and the cutting impact force endured by the tool is the largest, so the tool wear, milling force and cutting vibration are the largest. When the helix 

angle is larger, the direction of the resultant milling force deviates from the workpiece surface to a greater extent, and the cutting impact caused by the collapse of the 

graphite material is intensified, so the tool wear, milling force and cutting vibration also increase. Therefore, the impact of tool angle changes on tool wear, milling force and 

cutting vibration is caused by the combination of rake angle, relief angle and helix angle, so more attention must be paid to the selection.

Through a large number of scientific tests on the processing characteristics of graphite materials, PARA tools have optimized the geometric angles of relevant tools, thereby 

greatly improving the overall cutting performance of the tools.

3. Tool coating

Diamond-coated tools have the advantages of high hardness, good wear resistance, and low friction coefficient. At this stage, diamond coating is the best choice for graphite 

processing tools, and it also best reflects the superior performance of graphite tools; the hardness of diamond coating The advantage of alloy cutting tools is that it combines

 the hardness of natural diamond with the strength and fracture toughness of cemented carbide; however, domestic diamond coating technology is still in its infancy, and the 

cost investment is very large, so diamond coating is in the near future There will not be much development, but we can optimize the angle of the tool, material selection, etc. 

and improve the structure of the ordinary coating on the basis of ordinary tools. To some extent, it can be applied in graphite processing.

Diamond coated cutting tools

There is an essential difference in the geometric angle between diamond-coated tools and ordinary coated tools. Therefore, when designing diamond-coated tools, due to 

the particularity of graphite processing, the geometric angle can be appropriately enlarged, and the cutting groove can also become larger, and it will not Reduce the wear 

resistance of the tool edge; for ordinary TiAlN coatings, although its wear resistance is significantly improved compared to uncoated tools, compared with diamond coatings, 

its geometric angle should not be used when processing graphite. Make it smaller appropriately to increase its wear resistance.

For diamond coatings, many coating companies in the world currently invest a lot of manpower and material resources to research and develop related coating technologies. 

However, so far, foreign mature and economical coating companies are only limited to Europe; PARA, as a This excellent graphite processing tool also uses the world's most 

advanced coating technology for surface treatment to ensure the processing life and the economy and practicality of the tool.

4. Strengthening of tool edge

Tool edge passivation technology is a very important issue that is not generally taken seriously by people. The cutting edge of a cemented carbide tool after grinding with a 

diamond grinding wheel has microscopic gaps of varying degrees (i.e. micro chipping and saw edges). The performance and stability of graphite high-speed cutting tools 

have put forward higher requirements. In particular, diamond-coated tools must pass the passivation treatment of the cutting edge before coating to ensure the firmness and 

service life of the coating. The purpose of tool passivation is to solve the above-mentioned micro-notch defects of the sharpened tool edge, reduce or eliminate the sharpness, 

and achieve the purpose of being smooth, smooth, sharp, strong and durable.

5. Mechanical processing conditions of cutting tools

Choosing appropriate machining conditions has a considerable impact on tool life.

1. Cutting mode (climb milling and up-cut milling), the cutting vibration during down-milling is smaller than the cutting vibration during up-cut milling. During down milling, 

the cutting thickness of the tool is reduced from the maximum to zero. After the tool cuts into the workpiece, there will be no flicking phenomenon caused by failure to cut 

chips. The process system has good rigidity and low cutting vibration; during up milling, the cutting thickness of the tool From zero to maximum, the tool will scratch a path 

on the workpiece surface due to the thin cutting thickness in the early stage of cutting. At this time, if the cutting edge encounters hard points in the graphite material or chip 

particles remaining on the workpiece surface, it will cause the tool to fail. Knife flick or chatter, so the cutting vibration of up milling is large;

2. Blowing (or vacuuming) and immersing in EDM fluid processing to promptly clean the graphite dust on the surface of the workpiece will help reduce secondary wear of the 

tool, extend the service life of the tool, and reduce the impact of graphite dust on the machine tool screw and guide rail. ;

3. Select the appropriate high speed and corresponding large feed.

Summarizing the above points, the material, geometric angle, coating, edge strengthening and machining conditions of the tool play different roles in the service life of the 

tool. Each one is indispensable and complementary to each other. A good graphite tool should have smooth graphite powder chip removal grooves, long service life, the 

ability to perform deep engraving processes, and save processing costs.