Although the so-called super hard tools, diamond (PCD) tools are also easily damaged. The damage to PCD cutting tools is generally caused by the shape and material of the parts, tool shape and material processing conditions and grinding, etc.
The shape symmetry of the parts and good processing performance can reduce the damage to the tool. Factors that affect the severity of adhesion and wear, such as chemical composition and microscopic structure, mainly depend on hardness and cohesion.
When the cut material is strongly bonded to the tool surface and then cuts, the tool is easily damaged.
The basic properties of the processed material affecting tool wear and diffusion wear are high-temperature yield stress, the solubility of hard impurities and carbides in the material. Hard particles can cause surface abrasion.
Brittle tool materials are prone to blade breakage under the action of thermal and mechanical load cycles.
The breakage of PCD cutting tools mostly occurs at the end of the cutting. When the chips are discharged to the end of the tool and the workpiece material suddenly fractures, the stored elastic energy is suddenly released, which causes tool breakage.
Therefore, the size of the cutting angle for cutting the workpiece has a great influence on the tool damage. Using a cutting angle above 75 can prevent breakage.
In addition, tool wear and blade breakage are affected by tool vibration. When the rigidity of the machine and cutting system is not enough or the cutting depth is too large, it will cause tool vibration and increase the possibility of tool breakage. Overheating of the tool can cause burning.
To prevent tool damage, many manufacturers generally adopt the following measures:
Since PCD cutter blades, CBN tool blades, high-speed steel knives, hard alloy knives, metal ceramics, ceramics, and other coating tool materials all have their own characteristics, reasonable selection of appropriate tool materials should be based on factors such as workpiece material and cutting conditions. Materials with high strength and wear resistance should be used as much as possible.
As different PCD cutter blades have different characteristics in terms of shape and size, tip arc angle, chip breaking groove type, and tool bar type, suitable types of knives and tool bars should be selected according to the content of the processing, the material of the workpiece, the cutting conditions, rigidity, accuracy, operational performance, etc., in order to fully exert the cutting efficiency while ensuring that the shape and size and geometric parameters of the tool meet relevant standards and regulations, which is an important condition for ensuring processing accuracy.
The replacement cycle of PCD cutting tools due to wear should be clearly defined. This point is particularly important for turning tools.
Pay attention to the installation accuracy of PCD cutter tips, select a reasonable clamping method and clamping mechanism to ensure good operational processing performance and tip accuracy, and facilitate chip removal.
Consider comprehensive factors such as the nature of the processed material, PCD cutter shape and material, cutting conditions, and machine tool performance, and adopt the best measures for chip breaking, chip removal, and debris removal. For example, it is reasonable to add a chip breaking groove to a PCD turning tool to prevent chip entanglement with the tool and workpiece, affecting quality, increasing operator safety hazards, and rational chip breaking, which can ensure product quality and increase tool life.
Strengthen scientific management of PCD cutting tools. Firstly, the use of tools, such as the actual life of the tool, damage situation, and special tools with insufficient circulation or passability for other special purposes, should be statistically analyzed and processed to determine the reasons for the decline in tool cutting efficiency and adopt remedial measures. A tool file can be established, including tool number, production date, general cutting conditions, and usage, etc. Secondly, a reasonable tool purchase plan, consumption quota, and scrapping standards should be formulated and strictly implemented, and complete inspection regulations should be drawn up to strengthen inspection of tools upon purchase, after regrinding, and after installation.
In addition, PCD cutting tools must be protected by the tool tip and cleaned and maintained after use. Reasonable repair should be performed on damaged tools. The blade is not normally re-ground after wear and is worn smaller in size and then used. The damaged tool bar is usually repaired and then used.
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