You know the PCD cutting tool high frequency induction welding process? Currently, there are many people in the mechanical industry who are using PCD cutting tools but not enough understanding of their welding process. They often cannot determine which industries or fields PCD cutting tools are specifically used for. Now, we will explain the high frequency induction welding process of PCD cutting tools.
High frequency induction heating technology is a heating technology that developed in the early 20th century. It has the advantages of fast heating speed, internal heating of materials, high thermal efficiency, uniform and selective heating, good product quality, almost no environmental pollution, and easy automation production. It has been widely used in the field of superhard tool manufacturing.
High-frequency induction brazing refers to using the principle of electromagnetic induction to convert electromagnetic energy into heat energy in brazing filler metal and workpiece, heating the brazing filler metal to a molten state, and then welding the workpieces together. The heating speed of this process is fast, with a power density of 10-100 kW/cm2. The heating process can usually be completed in a few seconds, ensuring dimensional accuracy of parts, and the joint shear strength can reach 300-400 MPa.
Selection of the solder and filler metal is one of the main factors determining the brazing strength of PCD cutting tools. Their reasonable combination can ensure that the molten brazing filler metal has good fluidity, fully wets the base metal, reduces defects such as pores and slag inclusions, and obtains a beautiful appearance and excellent performance of the brazed joint. Silver-based filler metal is considered the current ideal filler metal, and the shear strength of brazed hard alloy joints is generally around 200 MPa. When using high-frequency induction brazing, its shear strength can reach 300-400 MPa.
Influenced by the cobalt-based binder inside PCD, a temperature of more than 700℃ will cause thermal damage to the tool material, affecting the cutting performance. Therefore, its welding cannot use high-temperature brazing technology as hard alloy. On the other hand, if the welding temperature is too low, it will affect the wetting of the filler metal, and the subsequent processing and use process will easily result in overflow. The welding time refers to the time of maintaining the welding temperature. If the holding time is not enough, the brazing material is difficult to melt fully and uniformly, which may cause poor brazing. If the holding time is too long, the cutting edge of the PCD cutting tool will be affected by high temperature, which affects its cutting performance. When high-frequency induction brazing the PCD composite sheet, the best constant temperature holding time is 15-20 seconds.
When using steel as the base material, cooling measures should be taken after welding, which can help reduce or eliminate the welding stress caused by the inconsistent thermal expansion coefficient of the tool material and the base material, and effectively prevent cracks. Common measures include artificial air cooling, placement on asbestos board at intervals, embedding in insulating powder such as quicklime or alumina, and placing in insulation furnace. After welding, the tool should be kept away from natural cooling in the air and not immersed in water or oil.
The excess brazing filler metal and surface oxide skin should be cleaned in time after welding. The filler metal can be removed by soaking it in hot water, but the best method for removing oxide skin is sandblasting. Sandblasting can be directly carried out after the welding is cooled, and the brazing seam should be inspected with a magnifying glass after cleaning. The ideal brazing seam should be smooth, smooth, without pores, cracks, and arc-shaped. Production experience shows that fine shot peening has a good effect of passivating surface defects.
The above is the introduction of the high frequency induction welding process of PCD cutting tools, mainly from the five aspects of high frequency welding principle, selection of high frequency welding welding materials and filler metals, welding temperature and holding time, cooling measures, and post-welding treatment. It helps everyone further understand them.
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