Tool technology that makes effective use of new materials

The basic requirement for machining is the rapid and cost-effective production of high quality products. This requirement is closely related to achieving high precision, high efficiency, and low cost in cutting. In recent years, cutting technology has developed rapidly in the fields of high-speed milling and micro-shape cutting. With the development and application of new engineering materials and the further miniaturization and refinement of parts and components, tool makers are actively developing high-efficiency tools for various processing applications. Building a Rapid Production System With the traction of investment in manufacturing equipment and export growth centered on the automobile industry, the demand for cutting tool products is increasing day by day, and tool manufacturers are expanding their production capacity at home and abroad. With the continuous increase of global cost competition, users are demanding more and more high value-added and efficient production. In order to meet the short-term and low-cost rapid production development trend, the key is to use a minimum of production equipment to achieve long-term automatic operation and processing. An effective method to promote the rationalization of production sites is to introduce composite cutting technology that can integrate multiple processes and a high-speed milling machine capable of high-speed, high-precision cutting of workpiece materials including hardened steel. Advanced cutting technologies such as compound cutting and high-speed hard milling are the core of a production method that minimizes the production of parts that are efficient, fast, and flexible (accommodation of production of different varieties and different batch sizes). However, any cutting method can not be separated by selecting the right cutting tool and determining the proper tool using technology. In recent years, progress has been made in tool materials (ceramics, hard alloys, TiC/TiN-based cermets, coated cemented carbides, etc.) with the advancement of machine tools, advances in high-precision machining technologies, and the increase in the number of difficult-to-machine materials. Significantly, the ever-changing cutting tool material must meet the following conditions: high hardness, wear resistance, high strength that resists cutting resistance and vibration impact, good high-temperature red hardness, easy heat treatment, and forming. Cemented carbide is characterized by its low hardness at high temperatures, in which the coated cemented carbide consists of a tungsten carbide cemented carbide substrate coated with one or more layers of titanium carbide (TiC). TiN, Al2O3 film materials, etc. Because the coating material's resistance to fusion, wear and heat resistance is superior to that of the substrate, it can perform high-speed cutting at a cutting speed exceeding the substrate. Due to the low coefficient of friction of the coating, the tool life can be extended.The development of high-speed milling technology requires that the tool material has good wear resistance, heat resistance and toughness. There are many products such as coated end mills that coat multi-layered composite films on ultra-fine particle cemented carbide substrates to improve cutting performance, and some ultrafine-grained cemented carbide materials have an average particle size of 1 μm or less. The toughness and flexural strength of the tool matrix are significantly improved.The composite coating is a combination of a variety of coating materials, layer by layer multilayer coating, in order to improve the cutting performance of the tool. In addition to titanium carbide and titanium nitride for high-speed cutting of steel parts, diamond and cubic boron nitride are now used, and silicon-based nano-coated tools with nano-level fine-grained coating have recently appeared for high-hardness steels. High-speed cutting and high-performance machining of mild steels Diamond coatings are coated with diamond materials with high adhesion and high wear resistance on the surface of carbide cutting tools.The microstructure of diamond coating is characterized by low amorphous content and high purity. It is well-proportioned and subtle, suitable for processing non-ferrous metals such as aluminum and copper, and non-metallic materials such as graphite, and has a wide range of processing. The hardness is second only to diamond cubic boron nitride sintered body (CBN) (hard The degree of HV3200 ~ 4000, which is about twice as high as that of cemented carbide) has excellent high-temperature hardness stability. At high temperatures of 1200 to 1300°C, it does not react chemically with metals, especially steels, and is therefore very suitable for heat-resistant alloys. Hardened high-alloyed steels and other high-hardness workpieces with HRC40 and above are machined and hard-working workpiece materials such as nickel-chromium-iron alloys and tungsten-chromium-cobalt-alloys are processed at cutting speeds of 150 m/min or more (but not suitable for interrupted cutting). The cost of cutting tools is more expensive than other cutting tools, so many users reuse the used blades for re-grinding and then use them again, but the sharpening itself also requires cost.In order to reduce the processing cost, the use of a small CBN tip has been used in recent years. Once abandoned tool structures, the demand for such disposable tool products is increasing.

Fig. Relationship between high temperature hardness and toughness of various tool materials

Solid carbide end mills refer to end mills made of hard alloys from the cutting edge to the tool shank. The machining targets include ordinary steels, high hardness steels, hard-to-cut materials, resins, and aluminum alloys. In addition, coated tool products coated with titanium nitride + aluminum (TiAlN, AlTiN) on ultra-fine grain cemented carbide substrates are also being developed. Gradient-function cutting edge tools are gradient-functionality tools that combine both cermet and coating properties. The 20 μm section below the surface of the cutting edge consists of a highly hardened titanium-based ceramic layer with excellent wear resistance, and the core is a hard alloy with a higher strength as it goes deeper. This material is constructed with a gradient structure and the material properties are constantly changing. It is worth expecting that this type of cutting tool has the same wear resistance and toughness comparable to that of ceramic coating, and the machined workpiece also has a cermet cutting tool (intermediate properties with carbide and ceramic). Processing similar precision surfaces. Therefore, ceramic-coated tools have so far been used for roughing, and the division of work for finishing with cermet tools may no longer be needed in the future. Development of cutting tools for difficult-to-machine materials New types of tools for various machining applications are constantly being developed. Here, we will examine only the latest developments in the cutting of difficult-to-cut materials, metal tooling tools, boring tools, and drilling tools. Efficient processing of difficult-to-machine materials can significantly reduce production costs and improve product quality. With advances in machine tool performance, tool materials, and tool edge design, cutting technologies for difficult-to-machine materials have also grown. There are three types of cutting edge for cutting hard-to-machine materials: 1 When machining hardened materials such as hardened steel and hard cast iron, the tool material is CBN and ceramic, and the tool cutting edge is designed as negative rake angle: 2 machining stainless steel In the case of titanium alloys, the cutting edge of the milling cutter uses a positive rake angle: 3 When machining soft metals such as aluminum alloys, the cutter blade shape uses an extra large rake angle and a large relief angle. Aircraft and power generation equipment components are mostly manufactured from difficult-to-machine materials such as heat-resistant superalloys and titanium alloys, and are often cut directly into a single block of metal. However, in many machining applications, due to the poor machinability of workpiece materials, the machining efficiency is low and the tool life is short, requiring a large amount of machining time and tools. For example, Ti6Al4V is a representative titanium alloy material, and is also a typical hard-to-machine material. It has a high specific strength and excellent heat resistance and corrosion resistance, and it has a strong chemical activity. It easily reacts with the tool during cutting, especially when cutting at high speeds, resulting in severe sticking. damage. Therefore, it is generally considered that it is appropriate to adjust the cutting speed to 150 m/min when high speed cutting is performed on Ti6Al4V. Other problems in the processing of refractory materials such as heat-resistant alloys include low thermal conductivity of the workpiece, the easy-to-focus cutting heat at the cutting edge of the cutting edge, and the easy adhesion of the tool to the workpiece. The solution to these problems is to improve the heat resistance and anti-adhesion of the tool by optimizing the helix angle, the cross-sectional shape, the cutting angle, and the optimal design of the cemented carbide material and the coating. For example, the 45° helical end mill can increase the sharpness of the cutting edge by increasing the helix angle, reduce the cutting resistance, and suppress the increase of the cutting temperature and the adhesion of the workpiece material. Taking into account the characteristics of heat-resistant super alloys and titanium alloys, the cutting edge is required to be sharp, easy to dissipate heat, and has good toughness and chip resistance. However, the processing properties of different types of heat-resistant super alloys and titanium alloys are different. In actual processing, the tool must be carefully selected according to the characteristics of the workpiece material, shape, clamping method, and mechanical rigidity. By selecting suitable cutting tools and processing conditions, high-speed, high-efficiency cutting of titanium alloys and other materials can be achieved and tool life can be extended. Development of high-performance tooling tools The use of metal molds for injection molding enables the rapid production of workpieces of the same shape at low cost and in large quantities. Recently, high-precision small or thin parts can also be processed by injection molding, but the prerequisite is the need to make high-precision metal molds. Tools for machining metal molds require high cutting performance. In order to adapt to the processing of high-precision molds, a variety of long-life, high-reliability solid carbide end mills have been developed. Improvements in tool performance include the use of (Ti, Al)N coatings and chip-rejection designs. The wavy three-wire groove adjusts the contact surface between the chip and the front edge of the blade edge to improve the chip flow performance. In addition, high-efficiency tools for mold processing such as ball-end mills with low cutting resistance and high sharpness have also been developed. In general, CBN tools are used for high hardness materials (such as hardened steel) with HRC60 or higher, because the greater the difference between the hardness of the tool and the workpiece, the longer the tool life. When cutting high hardness workpieces such as hardened steel, use Harder CBN tools are more advantageous than ceramic tools. Coated carbide end mills have long been considered to be difficult to machine workpiece materials with hardness above HRC60. For high precision machining of mechanical parts and metal molds, due to the high hardness of the hardened material and the large cutting resistance, the cutting speed and cutting depth of the end mill have to be affected. Anti-vibration boring bar for machining small parts is an indispensable tool for deep hole boring. Recently, in order to adapt to the processing needs of thin and light workpieces such as parts and components of IT products, the relevant anti-vibration masts have been vigorously developed. The increase in demand for home appliances and IT-related equipment such as computers, mobile phones, digital cameras, and DVD recorders has greatly changed the industrial structure of developed countries. The demand for cutting machining of small components assembled in these products is also increasing. For cutting of small components, even if the number of spindle rotations is set to high speed, the cutting speed can only stay in the low speed range due to the small workpiece diameter. Many manufacturers still use high-speed steel tools or brazed carbide tools for cutting. However, with the aging of sharpening equipment and the aging of technicians, it is increasingly difficult to make brazing tools and regrind. In addition, the cost of re-grinding further increases the cost of cutting tools. With the development of high-precision, high-efficiency, and low-cost development of parts and components, there is a growing demand for the use of non-reground carbide tools to efficiently process small parts. For boring this type of tool with a large amount of overhang, the anti-vibration performance of the tool is a big problem that cannot be ignored. Compared with traditional masts, vibration-proof masts are not prone to vibrations and can decay quickly even if vibrations occur. Currently developed tools have designed the shank to have a high-rigidity structure, installed a disposable blade, and designed the chip flutes to have a structure that retains only a minimum space, in order to prevent the rigidity of the tool from decreasing. Significantly reduced processing cycle The drilling process is often subjected to the severe test of high speed and high precision required by users. This is because drilling processing occupies a large proportion in the entire machining process, and its processing level is directly related to the improvement of product quality and production. The cost is reduced. In addition, how to reduce the environmental burden on the processing site, the drill also plays an exemplary role. In recent years, the development has attracted the attention of solid carbide drills, whose processing capability can be improved by more than 5 times than that of high-speed steel drills, and the tool life is about 10 times that of high-speed steel drills. Solid carbide drills using ultra-fine-grain carbides can be used for ordinary steels such as carbon steels and alloy steels, special steels such as stainless steels, high hardness steels such as die steels and hardened steels, grey cast irons, ductile irons, and aluminum alloys. Drilling of workpieces such as copper alloys. Many drill bits are treated with TiN, (Ti, Al)N and other coatings using a PVD (Physical Vapor Deposition) process. Due to the improvement of the toughness and reliability of the tool, even in the unstable cutting state where the cutting edge such as interrupted cutting is subject to mechanical impact and high heat, the drill bit is less susceptible to chipping and chipping. Solid carbide drills are also suitable for drilling hard-to-machine materials such as high hardness steels, stainless steels, and heat-resistant super alloys. At present, semi-dry cutting of aluminum has been practically used by some users. In order to further improve the tool life, tool makers and coating companies are exploring how to apply DLC (Diamond Like Carbon, diamond-like carbon) on the tool surface in PVD. It can be expected that the use of aluminum parts will further increase in the future in order to achieve lighter weight of products. In order to protect the environment and reduce costs, the demand for dry and semi-dry cutting operations will also continue to increase. In order to meet these needs, the most suitable tool will be continuously developed. In order to meet the ever-increasing user demand for cutting tools, tool manufacturers will aim to increase machining efficiency and further strengthen research and development in tool materials, coatings, and blade design.