Tool wear is the friction surface of the tool material tool gradual loss phenomenon. Tool wear morphology generally have the following two cases are the two sometimes wear both:
When cutting plastic materials, cutting thickness and cutting speed than the larger, the chips will wear out the rake face concave depression, the concave depression known as "crater." Place "crater" is produced by cutting the highest temperature of the place.
As the blunt edge of the cutting edge radius machined surface extrusion and friction at the bottom of the cutting edge will wear out a rear corner of the grooves is equal to zero, which is the flank wear. At lower cutting speeds, the smaller the thickness of cutting, the cutting brittle materials, the flank wear will occur.
Several factors affecting the tool wear
1, the tool material
Tool cutting tool material is to determine the fundamental factors for the processing efficiency, processing quality, processing costs and tool life greatly. The more hard tool materials, better wear resistance, higher hardness, lower toughness ipi.sooq.cn Copyright, the more brittle materials. Hardness and toughness is a contradiction, but also a key tool material should be overcome. For graphite tool, Common TiAlN coating may be suitably selected in the selection point is relatively good toughness, that is, the higher cobalt content; graphite to diamond-coated cutting tool can be appropriately selected in the selection point is relatively good hardness , the cobalt content is a little lower;
2, the geometry of the tool
Graphite select the appropriate tool geometry, the tool helps to reduce vibration, in turn, is not easy to collapse graphite piece missing;
(1) rake angle, when using negative rake angle machining graphite, tool edge strength is good, good impact resistance and friction performance, with the decrease of the absolute value of the negative rake angle, flank wear area changed little, but the overall decreasing trend, with positive rake angle machining, as the rake angle increases, the tool edge strength is weakened, but later led to flank wear intensified. Negative rake angle machining, cutting resistance, increasing the cutting vibration when using a large positive rake angle machining, tool wear serious, cutting vibration as well.
(2) the angle, if the angle increases, the tool edge strength decreases ZAOCHE168.com Copyright flank wear area increases. After the tool angle is too large, the cutting vibration strengthened.
(3) the helix angle, helix angle is small, and cut on the same cutting edge blade length of the longest piece of graphite, cutting resistance largest cutting tool to withstand the impact of the largest, and therefore the tool wear, cutting forces and vibration milling are the largest . To a large extent when the helix angle is large, the direction of deviation from the milling force workpiece surface, cutting graphite material impact caused by chipping intensified, so the tool wear, cutting forces and vibration milling it has also increased. Thus, the tool angle change on tool wear, impact milling force and vibration before cutting angle, back angle and helix angle integrated generated, so selection must pay more attention.
Through the processing characteristics of the graphite material a lot of scientific tests, PARA tool to optimize the geometry-related tools, thus making the overall cutting tool is greatly increased.
3, the tool coating
Diamond-coated tools for high hardness, wear resistance, and low coefficient of friction, at this stage diamond-coated graphite machining tool is the best choice, but also the tool that best reflects the superior performance of graphite; diamond-coated hard advantages alloy tool is a combination of natural diamond hardness and strength and fracture toughness of cemented carbide; but in the domestic diamond coating technology is still in its infancy, there is the cost of the investment is very large, so in the near future diamond coating there is not much development, but we can on the basis of common tools to optimize the angle of the tool, selection and other aspects of the structure and improve the general coating, in a way which is in graphite machining applications.
Diamond coated tools and tool geometry conventional coatings are essentially different, so the design of diamond coated tools when machining graphite due to the particularity of its geometry may be appropriate to enlarge the slot cut capacity becomes larger, it will not reduce tool wear front opening; TiAlN coating for a general, although significantly improved wear resistance than the uncoated cutting tool, but compared to the diamond coating, in which the graphite machining geometry should appropriate to put small, to increase its wear resistance.
Diamond coating, the coating of the world's large companies have invested a lot of manpower and material resources to research and development related to coating technology, but so far, foreign companies mature and economical coating confined to Europe; PARA as a excellent models graphite machining tool, the same while the world's most advanced coating technology for surface treatment of the tool to ensure that the processing life, ensure the economical and practical tool.
4, the tool edge enhancement
Technology is a tool edge passivation is not widespread attention, but is a very important issue. Carbide blade diamond wheel after grinding, there are different degrees of micro-gap (ie, minimal chipping and saw cut). High-speed machining graphite tool performance and stability of the proposed higher requirements, particularly in the diamond-coated tools must be passivated before coating the blade in order to ensure the coating is firm and life. The purpose of the tool is to solve the above passivation after sharpening tool edge micro-gap defect to reduce or eliminate the peak value www.ZAOCHE168.com, reach sleek flat, both sharp and strong and durable purposes.
5, the tool machining conditions
Select the appropriate processing conditions have a considerable effect on the life of the tool.
(1) cutting mode (climb milling and milling), cutting vibration is smaller than climb milling the cutting vibration. Milling cutter along the cut when the thickness is reduced from maximum to zero, the tool will not be playing the knife phenomenon caused by cutting chips after less than cut into the workpiece, rigid process system is good, cutting vibration; during milling, the tool cut thickness from zero to maximum, due to the cutting tool cuts the initial thickness of the thin section of the path will scratch repairer Copyright in the surface, then the edge of the graphite material if you encounter hard particles or residue on the surface of the chip particles, will cause the bomb knife or tool chatter, so cutting vibration milling large;
(2) blower (or vacuum) and liquid immersion EDM machining, clean the surface of graphite dust, secondary tool help reduce wear and extend tool life, reduce graphite dust on the machine screw and guide rail impact;
(3) Select the appropriate high-speed and a correspondingly large amount of feed.
Summary of the above points, the tool material, geometry, coatings, edge enhancement and machining conditions, tool life of the actor in different roles, indispensable and complementary. A good graphite tool, graphite should have smooth flutes, long life, can be deep engraving process can save processing costs.