Graphite is a very easy to cut material, but because the graphite material used as EDM electrode must have sufficient strength to avoid damage during operation and EDM processing, while the electrode shape (thin-walled, small rounded, sharp change), etc. It also puts higher requirements on the grain size and the strength of the graphite electrode, which results in the graphite workpiece being easily disintegrated during the processing and the tool being easily worn. The high cost, low efficiency, and often scrapped workpieces are the cause of the processing of the company. How to better process graphite electrodes?
One: Several things that affect the tool wear 1. Tool material: For the processing of graphite special tools, the ordinary TiAlN coating can be selected on the appropriate material to select a relatively good toughness, that is, a little higher cobalt content; for diamond coating Layer graphite tool, the appropriate choice of hardness is relatively good, that is, a little lower cobalt content;
2, the geometry of the tool: graphite tool to choose the right geometric angle, help reduce the tool vibration, in turn, graphite workpiece is not easy to collapse; 1 front corner, when the negative front angle processing graphite, the tool edge Good strength, good resistance to impact and friction, as the absolute value of the negative rake angle decreases, the flank wear area does not change much, but it tends to decrease overall. When positive rake machining is used, along with the rake angle With the increase, the cutting edge strength is weakened, which in turn leads to increased flank wear. When the negative rake angle is processed, the cutting resistance is large and the cutting vibration is increased. When the rake angle is used for machining, the tool wear is severe and the cutting vibration is also large. 2 In the rear corner, if the relief angle increases, the tool edge strength decreases, and the flank wear area gradually increases. When the tool clearance angle is too large, the cutting vibration increases. (3) When the helix angle is small, when the helix angle is small, the longest blade length of the same workpiece cutting into the graphite workpiece at the same time is the longest, the maximum cutting resistance, and the maximum cutting impact force that the tool bears. Therefore, the tool wear, the milling force, and the cutting vibration are the largest. When the helix angle is larger, the direction of the resultant force of the milling deviates from the surface of the workpiece, and the cutting impact caused by the disintegration of the graphite material is intensified, so that the tool wear, the milling force and the cutting vibration also increase. Therefore, the effect of tool angle change on tool wear, milling force, and cutting vibration is a combination of rake angle, relief angle, and helix angle. Therefore, attention must be paid to the selection. Through a large number of scientific tests on the processing characteristics of graphite materials, PARA cutters optimize the geometric angle of the relevant tools, thereby greatly improving the overall cutting performance of the tool.
3, the tool coating: processing of graphite tools should choose diamond coating, it's high hardness, good wear resistance, low friction coefficient and other advantages, at this stage diamond coating is the best choice for graphite processing tools, but also the most able to reflect The superior performance of the graphite tool; The advantage of the diamond coated carbide tool is that it combines the hardness of the natural diamond and the strength and fracture toughness of the cemented carbide; it can improve the tool life of nearly 10-20 times.
4. Reinforcement of tool edges: The tool edge passivation technology is a problem that has not been generally considered by people and is a very important issue. There are microscopic gaps (ie, micro-disintegration and sawing) with varying degrees of difference in the edge of the hard alloy tool after diamond grinding. High-speed cutting tool performance and stability of graphite put forward higher requirements, in particular, diamond-coated tools in the coating before the knife must be passivation treatment in order to ensure the coating's robustness and service life.
5, the tool machining conditions: Select the appropriate processing conditions for the life of the tool has a considerable impact. 1 Cutting method: Down milling. 2 Insufflation (or vacuuming) and impregnation of electrospark liquids to remove the graphite dust on the surface of the workpiece in time will reduce the secondary wear of the tool and prolong the service life of the tool. 3 Select the appropriate high speed and the corresponding large feed. To sum up the above points, the material, geometrical angle, coating, cutting edge strengthening, and machining conditions of the cutting tool play different roles in the service life of the tool. They are indispensable and complementary. A good graphite tool should have a smooth graphite powder flutes, a long service life, be able to deepen the engraving process, and save processing costs.
One: Several things that affect the tool wear 1. Tool material: For the processing of graphite special tools, the ordinary TiAlN coating can be selected on the appropriate material to select a relatively good toughness, that is, a little higher cobalt content; for diamond coating Layer graphite tool, the appropriate choice of hardness is relatively good, that is, a little lower cobalt content;
2, the geometry of the tool: graphite tool to choose the right geometric angle, help reduce the tool vibration, in turn, graphite workpiece is not easy to collapse; 1 front corner, when the negative front angle processing graphite, the tool edge Good strength, good resistance to impact and friction, as the absolute value of the negative rake angle decreases, the flank wear area does not change much, but it tends to decrease overall. When positive rake machining is used, along with the rake angle With the increase, the cutting edge strength is weakened, which in turn leads to increased flank wear. When the negative rake angle is processed, the cutting resistance is large and the cutting vibration is increased. When the rake angle is used for machining, the tool wear is severe and the cutting vibration is also large. 2 In the rear corner, if the relief angle increases, the tool edge strength decreases, and the flank wear area gradually increases. When the tool clearance angle is too large, the cutting vibration increases. (3) When the helix angle is small, when the helix angle is small, the longest blade length of the same workpiece cutting into the graphite workpiece at the same time is the longest, the maximum cutting resistance, and the maximum cutting impact force that the tool bears. Therefore, the tool wear, the milling force, and the cutting vibration are the largest. When the helix angle is larger, the direction of the resultant force of the milling deviates from the surface of the workpiece, and the cutting impact caused by the disintegration of the graphite material is intensified, so that the tool wear, the milling force and the cutting vibration also increase. Therefore, the effect of tool angle change on tool wear, milling force, and cutting vibration is a combination of rake angle, relief angle, and helix angle. Therefore, attention must be paid to the selection. Through a large number of scientific tests on the processing characteristics of graphite materials, PARA cutters optimize the geometric angle of the relevant tools, thereby greatly improving the overall cutting performance of the tool.
3, the tool coating: processing of graphite tools should choose diamond coating, it's high hardness, good wear resistance, low friction coefficient and other advantages, at this stage diamond coating is the best choice for graphite processing tools, but also the most able to reflect The superior performance of the graphite tool; The advantage of the diamond coated carbide tool is that it combines the hardness of the natural diamond and the strength and fracture toughness of the cemented carbide; it can improve the tool life of nearly 10-20 times.
4. Reinforcement of tool edges: The tool edge passivation technology is a problem that has not been generally considered by people and is a very important issue. There are microscopic gaps (ie, micro-disintegration and sawing) with varying degrees of difference in the edge of the hard alloy tool after diamond grinding. High-speed cutting tool performance and stability of graphite put forward higher requirements, in particular, diamond-coated tools in the coating before the knife must be passivation treatment in order to ensure the coating's robustness and service life.
5, the tool machining conditions: Select the appropriate processing conditions for the life of the tool has a considerable impact. 1 Cutting method: Down milling. 2 Insufflation (or vacuuming) and impregnation of electrospark liquids to remove the graphite dust on the surface of the workpiece in time will reduce the secondary wear of the tool and prolong the service life of the tool. 3 Select the appropriate high speed and the corresponding large feed. To sum up the above points, the material, geometrical angle, coating, cutting edge strengthening, and machining conditions of the cutting tool play different roles in the service life of the tool. They are indispensable and complementary. A good graphite tool should have a smooth graphite powder flutes, a long service life, be able to deepen the engraving process, and save processing costs.
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