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This study focuses on the formation of a single-line track in selective laser melting (SLM), based on the powder morphology, size distribution, and characteristics. A chromium-molybdenum-vanadium steel, AISI H13, was used as a metal powder. The relationship between the powder morphology, size distribution, and the powder-bed layer characteristics, such as the thermal conductivity and laser absorption under a N2 or Ar atmosphere, was determined. Subsequently, its effect on the built width, height, and contact angle was investigated by observing the cross-sectional profile of the structure. Finally, the powder morphology, size distribution, and characteristics were linked to the processability in SLM and were found to be closely related to the powder-bed layer characteristics, which affects the first deposition layer of the SLM H13 steel. The effect of the atmosphere on the contact angle is notable. The use of the Ar atmosphere to fabricate the continuous and stable structure at the minimum volume specific energy density (VSED) is reasonable because of its thermal property. The powder morphology, which depends on the atomization method, yields a variation in the bulk density and thermal property of the powder bed layer. The powder bed layer with the irregular powder can be influenced by the atmospheric characteristics because of its low bulk density. The effect of the powder-size distribution on the contact angle depends on the powder morphology. The spherical powder can perform the low-contact angle for a lower VSED.

Tool flank temperature at various intervals after cutting ISO C45 steel through dry turn-milling is measured using a two-color pyrometer with an optical fiber in order to investigate the cutting characteristics. The complicated undeformed chip geometry, which depends on various parameters such as cutting tool diameter, nose radius of cutting tool, number of tooth, workpiece diameter, tool-work revolution speed ratio, depth of cut, feed per tooth, tool axis offset, and cutting distance, is analyzed and visualized by the 3D-CAD system. The effect of cutting parameters associated with material removal rate (MRR) such as workpiece diameter, revolution speed, and feed rate on tool flank temperature is investigated in this study. The analysis by the 3D-CAD system indicated that workpiece diameter affects tool flank temperature, and an increase in 10 mm in diameter results in approximately 40 °C higher temperature at any workpiece revolution speed due to the variation in undeformed chip geometry. The tool flank temperature increases as the feed rate and workpiece revolution speed increase because the cross-sectional cutting area of undeformed chip increases with workpiece revolution speed, and the cutting time during the engagement of each flute also increases with feed rate. Further, almost similar values are obtained between the tool flank temperature and MRR when both the workpiece revolution speed and feed rate are changed.

The quality of built parts by selective laser melting (SLM) relies on the comprehension of the phenomena that takes place during the melting and solidification of the metal powder. The scattering of spatter particle as liquid metal during SLM process affects the layer consolidation of powder bed in addition to the surface quality of built part. The present study is focused on the spatter particle behavior of maraging steel during SLM to achieve a thorough understanding of the phenomena that occur during the melting and fusing of the metal powder. The spatter particles are tracked using high speed imaging, and the effects of the process parameters on the spatter particle behavior are investigated. The spatter particles ejected from the melt pool are also physically and chemically evaluated. The results showed that the spatter particles were classified as being spherical or satellite types, according to their scattered volumes; some spatter particles were larger than the particles in the initial metal powder. Most spatter particles were ejected from the droplet formed around the melt pool and from the melted powder in front of the melt pool; the number of spatter particles ejected from the melt pool was relatively low. The surface roughness affected the generation locations and tracks of the spatter particles, and the substrate surface wettability was the principal factor affecting the spatter particle behavior.

A workpiece attitude during polishing process is known to affect material removal rate distribution, which is one of the most significant properties in polishing process. Though, the effect of the attitude in double-sided polishing process has not been discussed in the past literatures. Hence, a method for estimating the distribution in double-sided polishing of a thick square workpiece considering the attitude is developed, and the effect of the attitude to the material removal rate distribution is investigated utilizing the method in the present study. In the developed method, the attitude is identified based on the equilibrium of force and moment applied to the workpiece by the contact against upper and lower pads. And distribution of contact pressure between the workpiece and pads is calculated under the identified workpiece attitude. Then, the material removal rate distribution is estimated from the contact pressure distribution and relative velocity distribution, which is calculated from the conditions of geometry and rotational speed, based on Preston’s law. It is confirmed that the material removal rate increases as the position is closer to the leading edge of the workpiece because of the workpiece tilt. And this variation increases as the workpiece becomes thicker and smaller. Therefore, it is confirmed that the effect of the workpiece attitude to the material removal rate distribution is significant, and considering the workpiece attitude is significant for investigating the material removal rate distribution in double-sided polishing of a thick or small workpiece.

In an actively driven rotary tool, the principal cutting force and tool tangential force are measured based on the power consumption of the main spindle and the tool spindle, respectively. In rotary turning, the principal cutting force, extent of chip flow angle change, and chip thickness are typically independent of tool rotation direction either clockwise or counterclockwise. The high-efficiency reciprocating turning can be regulated such that the tool tangential force acts in direct opposition to that of the feed force. In addition, cutting scenarios where the continuous chip is broken by the chip breaker are investigated using high-speed cameras.

Machining characteristics of electrochemical machining with ultrashort pulses were investigated using numerical analysis considering the inductance of a power supply circuit. In a pulse power supply circuit of ECM, stray inductance occurs in the electric feeders. Because stray inductance influences the flow of the pulse current, the formation of the electric double layer is affected by the inductance. In order to investigate the influence of the inductance on the machining characteristics, numerical analysis was conducted considering the inductance of the power supply circuit. The electric field was analyzed by numerical simulation considering the electric double layer and faradaic current, and the circuit equation of the pulse power supply was solved considering stray inductance of the pulse power supply. Analytical results show that the inductance increases the rise time of electric current flowing through the machining gap when pulse voltage is applied. Therefore, longer pulse duration of pulse power supply is necessary to form the electric double layer when the inductance is larger. The voltage continues to be applied to the working gap even after the pulse voltage becomes low, limiting the effect of ultrashort voltage pulses due to inductance.

This study examined the wear characteristics of ceramic tools when turning BN free-machining steel based on AISI 1045. An experiment was conducted to investigate why the alumina TiC-based ceramic tool showed remarkably better cutting performance than a pure alumina ceramic tool. The tool flank temperature, cutting force, and element distribution on the wear part were investigated. The cutting force and tool flank temperature of the BN free-machining steel were lower than those of standard steel, and the alumina TiC-based ceramic tool allowed for a lower cutting force and tool flank temperature than the pure alumina ceramic tool. After cutting of the BN free-machining steel, on the rake face, a deposited layer containing Al and N was detected, and the amount of the deposited layer on the alumina TiC-based ceramic tool was more than that on the pure alumina ceramic tool. Therefore, using an alumina TiC-based ceramic tool suppresses the tool flank temperature and makes it easier for a protective nitride layer to stick on the wear part; as a result, it has a clearly superior tool wear resistance than an alumina ceramic tool.

This study investigates the residual stress and deformation induced in a consolidated structure obtained through a layered manufacturing process. In this research, temperature and dynamic stress induced in the substrate during a selective laser melting (SLM) process were measured to investigate the influence of laser irradiation conditions on the development of residual stress and deformation in the consolidated structure. The stress was measured using a strain gauge that was attached on the bottom face of the substrate, whereas the temperature was measured using a thermocouple inserted in the substrate. The influences of the substrate height, consolidated structure height, and laser scanning pattern on the deformation and residual stress also were investigated experimentally. Additionally, the effects of different materials used as the substrate on deformation were investigated. It was found that during the laser consolidation process, temperature changes in the substrate caused repeated thermal expansion and shrinkage within the substrate, producing internal stress at the completion of the laser consolidation process. The stress that was induced in the substrate corresponds to the deformation result. Residual stress at the top of the consolidated structure increased whereas residual stress at the bottom of substrate decreased as the height of the consolidated structure increased. However, less deformation occurred when using stainless steel as the substrate.

This paper proposes a method for measuring the tool edge temperature during tapping. The infrared ray from the tool edge of the tapping tool was measured using a two-color pyrometer with an optical fiber. In addition, the vibration caused by contact between the first-act tool edge and the workpiece was sensed by an acceleration pickup. The outputs of the pyrometer from the tool edges and chips could be distinguished by analyzing the cutting behavior in the tapping process. The tool edge temperature was successfully measured for tapping of AISI 1045-based free-machining steel and stainless steels. The cross-sectional cutting area appears to control the tool edge temperature. The maximum tool edge temperatures with thee two steels at a cutting speed of 30 m/min reached almost 300 and 400°C, respectively. The cutting torque for stainless steel 303 was 3.4 N·m lower than when tapping stainless steel 304. The tool edge temperature for stainless steel 304 reached the maximum value of 510°C. The temperature for stainless steel 303 was about 100°C lower than of stainless steel 304.The tool edge temperature for stainless steel 304increased linearly with the cutting speed. The rate of increase in the tool edge temperature with increase in cutting speed from 25 m/min to 30 min was larger than that from 20m/min to 25min. Therefore, the tool edge surroundings apparently became harder with an increase of cutting speed.

This research deals with the hard turning of cemented carbide with CBN and diamond tools, and focuses on the tool performance, mainly tool wear with respect to cutting force and cutting temperature. The internal turning tests without cutting fluid are executed with the vertical machining center. Seven types of tool materials: SC, CVD-SC, two PCDs, BL-NPD (Binderless nano-polycrystalline diamond) and CBN: are selected for cutting three grades of cemented carbides WC having the different Co binder content (12%, 20% and 25%). Attrition has been found to be the main tool wear mechanism for all tools with slight adhesion of the workpiece binder on the tool face. In cutting of softest carbide WC-m (25% Co), the polycrystalline CBN tool has the lowest tool wear than any other PCD tools. In turning of harder carbides WC-d (20% Co) and WC-t (12% Co), both polycrystalline CBN and PCD cannot be used continuously due to their low hardness, and BL-NPD, SC and CVD-SC tools are applicable. And the BL-NPD tool has the best cutting performance with less flank wear. As for WC-d, extremely stable cutting can be done with BL-NPD where the principal cutting force is kept almost constant at 40 N. Only BL-NPD tool can continue to turn the hardest WC-t. In spite of turning hard materials, the tool temperatures measured are relatively low below 450°C due to the high thermal conductivities of tool materials. However, cutting temperature is directly related to the tool wear and cutting force rather than thermal conductivity of tool in turning of WC-m and WC-t.

In this paper, the measurement method of tool edge temperature using a two-color pyrometer with an optical fiber in wet cutting is proposed. Using the proposed method, the high pressure air supplied from the small hole where an optical fiber is inserted prevents coolant from adhering to the optical fiber edge and makes temperature measuring possible. The influence of this supplied air pressure on the tool edge temperature is negligible in the 0.05Mpa to 0.6MPa range. In this way, the temperature of CBN and PCD tool edge is measured in wet cutting of Ti-6Al-4V. As a result, the tool edge temperature increases rapidly with the increase of cutting speed. In dry cutting, PCD tool edge temperature is almost 100 °C lower compared with CBN tool edge temperature. By coolant supply, PCD tool edge temperature decreases greatly. For example, when cutting speed is set at 300m/min, PCD tool edge temperature decreases by 350°C, while CBN tool edge temperature decreases by only 70°C.

Thermal stress cleaving is a prospective technique for separating thin plates of brittle materials such as silicon, ceramic and glass. This study, deals with a new method which provide the initial fracture on the edge of workpiece. The initial fracture such as crack, scratch and groove is the starting point of crack propagation in laser cleaving and the crack propagates along laser scanning path from the initial fracture. In previous study, the initial fracture is created by Vickers indenter. Since shape of Vickers indenter is pyramid, the unnecessary cracks propagate. In addition, lateral cracks are created at the surface. Because of cracks, the quality of thermal stress cleaving is poor. In this study, a pre-groove is used as the initial fracture. The pre-groove is formed on the workpiece surface by pulsed Nd:YAG laser irradiation through a cylindrical micro-lens. The cylindrical micro-lens is made by the irradiation of Er:YAG laser to the surface of acrylic board. Silicon wafer is used as a workpiece. Continuous Nd:YAG laser is used for laser cleaving. By using this method, there is no unnecessary cracks happen, and subsequently improve the quality of thermal stress cleaving.

In this research, Milling combined Laser Sintering System (MLSS) is used to make a sintered material. MLSS is a rapid tooling system using a fine metallic powder integrated with machining process whereby it can do laser sintering of fine metallic powder and also high-speed milling. This paper deals with the investigation of sintered material machinability by measuring its specific cutting energy and tool flank temperature. Carbon steel (JIS S55C) is selected as a standard steel. The effects of cutting conditions, laser consolidation energy density, powder consolidation mechanisms and unsintered powder on its machinability are measured. It is demonstrated that tool flank temperatures for all sintered materials are higher than JIS S55C. Low energy density for consolidation of metal powder increases the machinability of sintered materials. Cutting at the partially molten powder decreases the machinability of sintered material. Cutting with the existence of unsintered metallic powder surrounding the sintered material diminishes its machinability.

This study investigates the influence of cutting fluid on the cutting temperature in end milling of a titanium alloy. As the cutting temperature, the tool edge temperature was measured using a two-color pyrometer with an optical fiber. A helical cutter with an indexable insert of 50-mm diameter was used. The cutting speed was set at 100 m/min. The feed rate was set at 0.1 mm/tooth. The radial and the axial depth of cut were set at 12 and 5 mm, respectively. Under this cutting condition, a method for measuring the transitional tool edge temperature in one cut was established. One cut took ～15.22 ms under this cutting condition. In the case of up cut, the temperature under dry conditions increased rapidly at the start of cutting and then converged. The temperature under wet conditions increased slowly until 7 ms and then converged. In the case of down cut, the temperature under dry conditions increased rapidly at the start of one cut and then remained almost constant, before increasing slightly at the end of one cut. The temperature under wet condition increased rapidly at the start of one cut and then decreased slowly until the end of one cut. The larger tool edge temperature reduction effect caused by the cutting fluid was obtained near the end of one cut, where the uncut chip thickness was smaller. Due to the small uncut chip thickness, the cutting fluid is effective at the end of each contact between tool and workpiece and then the cutting edge temperature decreases considerably.

Selective Laser Sintering/Selective Laser Melting (SLS/SLM) is one of the most promising additive manufacturing (AM) techniques that are widely accepted by the industrial community. This is due to its high flexibility in processing different types of material under various conditions. However, the capability of the end product to have a desirable quality comparable to traditional processing techniques is still not achievable. Consolidation characteristics and the influence of processing parameters are important in determining the SLS/SLM part quality. In this paper, the consolidation process of ferrous-based metal powder is examined by monitoring the real-time consolidation process. A high-speed camera was utilized with telescopic lenses in order to monitor the interaction of laser and material within the powder fusion zone (PFZ). Based on the study, the line consolidation can be classified into five different consolidation types. The line consolidation characteristics were analyzed according to the line consolidation width, PFZ, consolidated agglomerate diameter and metal particle splattering behavior. The influence of laser power and scan speed on these characteristics was analyzed. It was also found that the line consolidation width, PFZ, consolidated agglomerate diameter and splattering were increasing with the increase of laser power. In contrast, with the increase of scan speed the result was vice versa. These phenomena can be explained with respect to the heat transfer behavior that took place during the interaction between the laser beam, metal powder and substrate surface. The consolidation mechanism that occurred during consolidation is also reported.