Abstract: Single crystal silicon carbide (SiC) is a new semiconductor material that has a great potential to be widely used. However, SiC is a kind of difficult-to-machine material due to its extreme hardness and brittleness. The present study investigated the machinability of single crystal SiC using dry laser and three different water-laser co-machining processes. The results indicate that using the hybrid laser-waterjet micro-machining to micro-groove single crystal SiC can derive the clean and straight edges and thermal damage-free grooves.
Abstract: As a kind of commonly used tools, junior hacksaw plays an important role in our daily life. A new kind of bimetal band saw taken low carbon medium alloy steel X32 as the backing material and the high-speed steel M42 as the saw tooth material is developed. In this paper, a new method to machine the bimetal band saw with wire electrical discharge machining (WEDM) is introduced. The processing route for common tooth profile is calculated. The fixture with specific angles is designed with CAD software (proe5.0) and machined with 3D printing technology. The experiments show that bimetal band saw machined with WEDM method has better surface quality compared with that machined through the traditional grinding process. Without any burrs, the new bimetal band saw is more resistant to wear and has a longer service life.
Abstract: The high hardness of brittle materials always make it hard to machine with traditional grinding wheels. Conventionally a diamond grinding wheels was used to improve the poor processing capability. Usually the specific grinding energy had been used as an indicator of machinability. According to its definition, the specific grinding energy increases with the active contact area of the grinding wheel decreases. In other words, reducing the surface contact area of the grinding wheel can enhance the specific grinding energy effectively. Conditioning grooves on grinding wheels not only enhance the specific grinding energy, but also achieve the effect of reducing the heat dissipated during the grinding processes. With the proper selection parameters, the high cost of diamond grinding wheel may be replaced by less expensive conventional green carbon and aluminum oxide wheel. In this studies, the relationship between the surface topography of grinding wheels and the grinding capability of brittle materials was investigated. The results show that, the traditional grinding wheel dressing properly while the depth of cut less than 20μm with the rhombic pattern and the depth of cut more than 20μm with the groove-like pattern can grind the brittle materials as good as using diamond wheel.
Abstract: In this paper, experiments were conducted to investigate the effects of cylindrical electrode and helical electrode on the micro electrical discharge machining (EDM) performances during micro-hole machining of titanium alloy. The results show that the material removal rate (MRR) and the tool wear rate (TWR) increase with open circuit voltage, regardless of electrode shapes. Compared to the cylindrical electrode, helical electrode can result in higher MRR and lower relative tool wear ratio (RTWR). It can be concluded that the helical electrode is more suitable than cylindrical electrode for machining micro parts.
Abstract: The milling of AISI 321 stainless steel which has wide engineering applications particularly in automobile, aerospace and medicine is of great importance especially in the conditions where high surface quality is required. In this paper, L16 orthogonal array design of experiments was adopted to evaluate the machinability of AISI 321 stainless steel with coated cemented carbide tools under finish dry milling conditions, and the influence of cutting speed ( V ), feed rate ( f ) and depth of cut ( ap ) on cutting force, surface roughness and tool wear was analysed. The experimental results revealed that the cutting force decreased with an increase in the cutting speed and increased with an increase in the feed rate or the depth of cut. The tool wear was affected significantly by the cutting speed and the depth of cut, while the effect of the feed rate on the tool wear was insignificant. With the cutting speed increased up to 160 m/min, a decreasing tendency in the surface roughness was observed, but when the cutting speed was further increased, the surface roughness increased. The effect of the feed rate and the depth of cut on the surface roughness was slight.
Abstract: This article studies the forces and tool wear behavior in the milling process of Ni3Al-base superalloys with cemented carbide cutting tools. The effects of cutting parameters on the machinability of these superalloys are experimentally discussed. The results indicate that the forces increase with the increase of the axial depth of cut, the radial depth of cut and the feedrate per tooth. The cutting tools wear rapidly in the milling process of Ni/Al superalloys. The cemented carbide cutting tool with TX coating is more suitable for machining Ni/Al superalloys when compared with the tool with TiCN coating.
Abstract: The origin of drilling force in drilling with twist drill is quite complicated owning to the complex shape of the drill bit cutting edges. In this paper, the drilling experiments both with and without the ultrasonic were designed and conducted on aluminum alloy with pre-drilled hole. The drilling force was tested and the different effects between the cutting edges of the twist drill on the drilling force were analyzed under various drilling parameters including the spindle speed, feed rate and vibration amplitude. The drilling force of conventional drilling (CD) and ultrasonic assisted drilling (UAD) was characterized and the roles of the ultrasonic vibration in drilling were discussed.
Abstract: In order to study the complex groove inserts in the cutting process caused by temperature variation of cutting,Using multi factor cutting method and combined with finite element simulation technology, from cutting parameters and chip-breaking groove two aspects influence on cutting temperature and cutting force cutting tests were carried out and experimental study on the complex groove turning insert edge chamfering, rounded cutting edge radius on cutting temperature effects. Also tested the effects of temperature on the chip shape cutting and breaking, and analyzed the temperature on the Influence law of cutting tool wear, thus providing a theoretical basis for tool wear.
Abstract: The cutting edge radius and cutting thickness as well as feed rate are in the same order of magnitude in micro-cutting. So it will appear a situation that the chip cannot be formed when the cutting thickness is less than a certain value which is the minimum cutting thickness. It is possible to find a method that can determine the minimum cutting thickness in the finite element simulation of micro-cutting according. In this paper, a series of finite element simulations of different workpiece materials in micro-cutting are carried out and several different minimum cutting thicknesses are obtained. It is shown that the minimum cutting thickness is related to the workpiece material in micro-cutting. When the workpiece materials are different, the minimum cutting thicknesses obtained are also different in micro-cutting.
Abstract: Grinding force is an important indicator related to processing efficiency and residual strength in the progress of grinding SiC. With the method of ultrasonic assisted grinding (UAG), this paper studied the influence of four parameters on grinding force based on orthogonal experiment, namely vibration amplitude, depth of grinding, feed rate and spindle speed. A series of results with high efficiency and low grinding force were obtained. A regression empirical model under the condition of UAG was established and verified. It was also proved that ultrasonic vibration was conducive to improve the ground surface quality of workpiece.