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Hardware Interpretation: Reasons for the wear of graphite tools and solutions?
Graphite is a very easy to cut material, but the graphite material used as the EDM electrode must have sufficient strength to avoid damage during handling and EDM processing, as well as electrode shape (thin wall, small rounded corners, sharp changes), etc. High requirements are also placed on the grain size and strength of the graphite electrode, which causes the graphite workpiece to be easily broken during processing and the tool to be easily worn. The cost of processing is high, the efficiency is low, and the workpieces are often scrapped. How to better process graphite electrodes?
The technical backbone of the Nyster Technology Department has finally found the cause and solution after repeated improvement for half a year. From then, the reporter will solve the mystery for you.
Points affecting tool wear
1. Tool material: For the special tool for processing graphite, the ordinary TiAlN coating can choose a relatively better toughness in the material selection, that is, the cobalt content is slightly higher; for the diamond coated graphite tool, it can be appropriately selected in the material selection. Choose a hardness that is relatively better, that is, the cobalt content is slightly lower;
2, the geometric angle of the tool: graphite tool selection of the appropriate geometric angle, help to reduce the vibration of the tool, in turn, the graphite workpiece is not easy to collapse; 1 front angle, using the negative rake angle to process graphite, the tool edge The strength is good, the impact resistance and friction performance are good. With the decrease of the negative rake angle* value, the wear area of the flank face does not change much, but the overall trend is decreasing. When the positive rake angle is used, the front angle is used. As the diameter increases, the tool edge strength is weakened, which in turn leads to increased wear on the flank. When the negative rake angle is processed, the cutting resistance is large, and the cutting vibration is increased. When the large positive rake angle is used, the tool wear is severe and the cutting vibration is also large. 2 Back angle, if the back angle increases, the tool edge strength decreases, and the flank wear area gradually increases. When the back angle of the tool is too large, the cutting vibration is strengthened. 3 helix angle, when the helix angle is small, the blade length of the graphite workpiece cut on the same cutting edge is long, the cutting resistance is large, and the cutting impact force* of the tool is large, so the tool wear, milling force and cutting vibration are *large of. When the helix angle is large, the direction of the milling force is larger than the surface of the workpiece, and the cutting impact caused by the collapse of the graphite material is intensified, so that the tool wear, the milling force and the cutting vibration are also increased. Therefore, the influence of tool angle change on tool wear, milling force and cutting vibration is the combination of front angle, back angle and spiral angle, so we must pay more attention to the selection. Through a large number of scientific tests on the processing characteristics of graphite materials, PARA tools optimize the geometric angle of the relevant tools, so that the overall cutting performance of the tool is greatly improved.
3, the coating of the tool: processing graphite tool should choose diamond coating, it has high hardness, good wear resistance, low friction coefficient, etc. At this stage, diamond coating is the best choice for graphite processing tools, and * can reflect The superior performance of graphite tools; the advantages of diamond-coated carbide tools are the combination of the hardness of natural diamond and the strength and fracture toughness of cemented carbide; it can increase the service life of nearly 10-20 times.
4, the cutting edge of the tool: the cutting edge passivation technology is a problem that has not been universally recognized, but also very important. The edge of the cemented carbide tool after the grinding of the diamond wheel has a microscopic notch of different degrees (ie, micro chipping and sawing). Graphite high-speed cutting tool performance and stability put forward higher requirements, especially diamond coating tools must be passivated by the knife edge before coating to ensure the firmness and service life of the coating.
5. Machining conditions of the tool: Selecting the appropriate machining conditions has a considerable impact on the life of the tool. 1 cutting method: down milling. 2 blowing (or vacuuming) and impregnating electric spark fluid processing, timely cleaning the graphite dust on the surface of the workpiece, which is beneficial to reduce the secondary wear of the tool and prolong the service life of the tool. 3 Choose the appropriate high speed and the corresponding large feed. In summary of the above points, the tool material, geometric angle, coating, edge reinforcement and machining conditions play different roles in the life of the tool, and they are indispensable and complementary. A good graphite tool should have a smooth graphite powder chip flute, long service life, deep engraving processing, and can save processing costs.
The technical backbone of the Nyster Technology Department has finally found the cause and solution after repeated improvement for half a year. From then, the reporter will solve the mystery for you.
Points affecting tool wear
1. Tool material: For the special tool for processing graphite, the ordinary TiAlN coating can choose a relatively better toughness in the material selection, that is, the cobalt content is slightly higher; for the diamond coated graphite tool, it can be appropriately selected in the material selection. Choose a hardness that is relatively better, that is, the cobalt content is slightly lower;
2, the geometric angle of the tool: graphite tool selection of the appropriate geometric angle, help to reduce the vibration of the tool, in turn, the graphite workpiece is not easy to collapse; 1 front angle, using the negative rake angle to process graphite, the tool edge The strength is good, the impact resistance and friction performance are good. With the decrease of the negative rake angle* value, the wear area of the flank face does not change much, but the overall trend is decreasing. When the positive rake angle is used, the front angle is used. As the diameter increases, the tool edge strength is weakened, which in turn leads to increased wear on the flank. When the negative rake angle is processed, the cutting resistance is large, and the cutting vibration is increased. When the large positive rake angle is used, the tool wear is severe and the cutting vibration is also large. 2 Back angle, if the back angle increases, the tool edge strength decreases, and the flank wear area gradually increases. When the back angle of the tool is too large, the cutting vibration is strengthened. 3 helix angle, when the helix angle is small, the blade length of the graphite workpiece cut on the same cutting edge is long, the cutting resistance is large, and the cutting impact force* of the tool is large, so the tool wear, milling force and cutting vibration are *large of. When the helix angle is large, the direction of the milling force is larger than the surface of the workpiece, and the cutting impact caused by the collapse of the graphite material is intensified, so that the tool wear, the milling force and the cutting vibration are also increased. Therefore, the influence of tool angle change on tool wear, milling force and cutting vibration is the combination of front angle, back angle and spiral angle, so we must pay more attention to the selection. Through a large number of scientific tests on the processing characteristics of graphite materials, PARA tools optimize the geometric angle of the relevant tools, so that the overall cutting performance of the tool is greatly improved.
3, the coating of the tool: processing graphite tool should choose diamond coating, it has high hardness, good wear resistance, low friction coefficient, etc. At this stage, diamond coating is the best choice for graphite processing tools, and * can reflect The superior performance of graphite tools; the advantages of diamond-coated carbide tools are the combination of the hardness of natural diamond and the strength and fracture toughness of cemented carbide; it can increase the service life of nearly 10-20 times.
4, the cutting edge of the tool: the cutting edge passivation technology is a problem that has not been universally recognized, but also very important. The edge of the cemented carbide tool after the grinding of the diamond wheel has a microscopic notch of different degrees (ie, micro chipping and sawing). Graphite high-speed cutting tool performance and stability put forward higher requirements, especially diamond coating tools must be passivated by the knife edge before coating to ensure the firmness and service life of the coating.
5. Machining conditions of the tool: Selecting the appropriate machining conditions has a considerable impact on the life of the tool. 1 cutting method: down milling. 2 blowing (or vacuuming) and impregnating electric spark fluid processing, timely cleaning the graphite dust on the surface of the workpiece, which is beneficial to reduce the secondary wear of the tool and prolong the service life of the tool. 3 Choose the appropriate high speed and the corresponding large feed. In summary of the above points, the tool material, geometric angle, coating, edge reinforcement and machining conditions play different roles in the life of the tool, and they are indispensable and complementary. A good graphite tool should have a smooth graphite powder chip flute, long service life, deep engraving processing, and can save processing costs.