Burnishing Characteristics of Sliding Burnishing Process With Active Rotary Tool Targeting Stainless Steel

This paper investigates the burnishing characteristics of a developed sliding burnishing method with active rotary tool targeting a martensitic stainless steel. Two types of martensitic stainless steel, annealing (AN) stainless steel and quenching and tempering (QT) stainless steel, were targeted. The burnishing characteristics evaluated included surface roughness, profile, microstructure, subsurface hardness, bending property, and corrosion resistance. A sufficiently smooth surface, approximately Ra = 0.1 μm and Ra = 0.025 μm in both materials, respectively, was obtained using the developed burnishing method; irregular profile smoothing occurred due to the material flow of the subsurface. The subsurface hardness increased at a depth of 40 μm or more when using the developed burnishing method on the AN material, but no effect was observed for the QT material. Moreover, the bending yield point and strength of the sheet shape workpiece increased by applying the burnishing process to the AN material. The influence of the burnishing process on the bending properties was also observed for the QT material. Corrosion resistance can be improved through the burnishing process.

Error Analysis by Square 3 x 3 Machining Method for Five-Axis Machining Centers

The establishment of international standards for 5-axis control machining centers has been supported by the high interest of each country. Internationally, various accuracy inspection methods have been proposed and widely discussed. Accuracy measuring devices for these purposes have also been proposed. In 2014, inspection methods for 5-axis machines were published in ISO 10791-6 and 10791-7. In this research, we propose a test method to process 9 square faces as a new accuracy evaluation method. We simulate the influence of assembly error by the proposed square 3 × 3 machining method on the machined surface. By processing 9 square faces with different tool angle on the same plane, it was possible to evaluate the influence of assembly errors in the 5-axis machining center on the machined surface. Nine surfaces machined by the square 3 × 3 processing method cause differences in surface height due to alignment errors. In addition, nine machined surfaces become all diagonal not parallelism. The alignment errors of the 5-axis machining center is identified by evaluating the orientation of the machined surfaces. Specifically, we propose a newly method to measure the height difference of nine surfaces. Then, the possibility of identifying the alignment error of the 5-axis machining center using the measurement results is shown.

Development of an Optical Angle Sensor With a Mode-Locked Femtosecond Laser Source for Surface Profile Measurement

Angle sensors based on the laser autocollimation are often employed to evaluate surface profiles of a target of interest. The authors have developed a femtosecond laser angle sensor, in which a spectrometer or an optical spectrum analyzer with a single-mode fiber is employed as the photodetector for simultaneous capturing of the multiple optical modes. In this paper, the concept of the femtosecond laser angle sensor is applied to evaluate the surface profile of a target of interest. An optical setup is designed in such a way that each mode in the spectrum of the mode-locked femtosecond is utilized as the laser beam to measure the local slope of a measurement target at each different point to evaluate the surface profile. Some basic experiments are carried out by using the developed optical setup with a mode-locked femtosecond laser source to evaluate basic performances of the developed optical setup as an optical angle sensor.

Chatter Stability Prediction of Cutting Process With Process Damping Utilizing Finite Element Analysis

This paper presents a new approach to predict chatter stability in cutting considering process damping. Traditional chatter stability analysis methods enable to predict stable or unstable conditions. Under unstable conditions, the chatter vibration can increase theoretically infinitely. However, chatter vibration is damped at a certain amplitude in real process due to process damping, i.e., the cutting process is stabilized by means of tool flank face contact to the machined surface. In order to consider the influence of the process damping, a simple process damping force model is introduced. The process damping force is assumed to be proportional to the structural displacement. The process damping coefficient is a function of the vibration amplitude and the wavelength. In order to identify the coefficients, a series of finite element analysis is conducted in the present study. Identified coefficients are introduced into the conventional zero-order-solution in frequency domain. The proposed model calculates chatter stability limit assuming process damping with finite amplitude. Hence, this analysis enables to estimate the amplitude-dependent quasi-stable conditions. Analytical results for thee face turning operation demonstrated influence of process damping effect on resultant vibration amplitude quantitatively.

Twin Roll Casting of Copper Alloy C19210 Using Commercial Scale Machine

Copper alloy C19210 have excellent corrosion resistance, heat resistance, and conductivity, and is used for precision electronic parts such as lead frame materials. Conventionally, copper alloy strips are manufactured by repeating heat treatment and cold rolling, and have a problem that it is multi-process and production cost is expensive. On the other hand, twin roll casting can improve the above problems because strips are made directly from molten metals. In this study, twin roll strip casting of copper alloy C19210 using commercial scale machine was operated. The aims of this study is to investigate the possibility of strip casting for copper alloy. The effect of the side dam and release agent was researched. The effect of rolls speed on the strip surface condition was researched. The improved side dam prevented molten metal leakage. The release agent prevented sticking of the manufactured strip to the roll surface. The strip produced at roll speed of 7 m/min and 10 m/min had a lot of metallic luster. Moreover, the strip produced at roll speed of 7 m/min had more metallic luster than the strip produced at roll speed of 10 m/min. The lower the roll speed is, the greater the rolling load is. At a roll speed of 7 m / min, the rolling load became the maximum rolling load of the equipment. For producing strips with copper alloy C19210, higher rolling loads are preferred.

Control of Material Flow During Friction Stir Welding Between Aluminum and Steel by Welding Tool Shape

For the Friction stir welding (FSW) between aluminum and steel is important to fabricate vehicles with light weight and high strength for safety at low cost. For the fabrication of sound weld, it is necessary to control the material flow during FSW. In this study, the material flow during FSW was elucidated by numerical simulation by computational fluid dynamics (CFD) analysis and simulation experiment by transparent Poly-vinyle chloride (PVC) as simulant of aluminum and tracer material. Based on this material flow analysis, several shapes of welding tool were examined for control of material flow during FSW. Scroll shoulder is effective for enhancement of stirring zone by increasing material velocity around the probe. Flute and fine screw probe promote the material flow in depth and horizontal direction. The welding tool with scroll shoulder and flute and fine screw probe achieved sound weld with highest tensile strength of 120.4 MPa.

Development of High-Performance Polycrystalline CVD Diamond Coated Cutting Tool Edge With Femtosecond Laser

To realize the high performance of CVD diamond coated tools, a tool edge shaping process named pulse laser grinding (PLG) was developed with short pulse laser in our group previously. In this study, femtosecond laser was innovatively to be used to conduct the PLG process, since femtosecond laser is famous for its less thermal impact and some newly reported surface modification effect. The results show that PLG processing under high laser fluence of femtosecond laser could achieve roundness around 1 μm, which is similar to that of conventional PLG process with nanosecond laser, although the roughness of processed surface has been worse due to the redeposited debris. Furthermore, an interesting phenomenon has been confirmed again that under low laser fluence irradiation of femtosecond laser, the CVD diamond surface shows improved crystallinity of diamond structure. Based on this, a two-step tool edge processing method was proposed, which could realize the edge shaping and surface modification together with one laser processor. And the results show that the processed tool edge with much less edge roundness and surface roughness, and the tip part with better diamond crystallinity, indicating that sharper and hardness tool edge could be possibly to be realized with femtosecond laser.

Removal Machining Performances by Using Inert Gas Filled Micro Bubble Coolant

The authors have proposed a micro bubble coolant in which micro bubbles (20∼50μm in diameter) are included in water soluble coolant. In the previous study, it was confirmed that the tool life was improved by applying the micro bubble coolant to various machining operations such as drilling, turning and grinding. Also, purification effects of the micro bubble coolant were found. In this study, micro bubble coolant in which inert gases (N2 and CO2) were mixed was proposed to be applied to grinding processes for further improvement in grinding performances. When nitrogen gas (2L/min) was mixed with the micro bubble in the water soluble coolant (70L), amount of the dissolved oxygen in coolant decreased to 0.5mg/L. And concentration of the carbon dioxide gas in the coolant increased to 100mg/L when carbon dioxide gas (2L/min) was mixed in. From the result of grinding test on high speed steel, it was found that grinding performances improved when the micro bubble coolant with any of air, N2 and CO2 gases was used. The grinding force decreased by a factor of about 15% and the tool life increased by 20∼30%. When nitrogen gas was mixed in, the surface roughness improved by about 15%. In grinding stainless steels, performances such as grinding force, tool life and surface roughness improved by 10% when nitrogen gas was mixed in. In addition, a tendency of flank wear reduction and improvement in the surface roughness were observed when air micro bubble was mixed into the coolant in the turning of high carbon steel and Inconel 718 as well. When N2 micro bubble was generated in the coolant, a flank wear was reduced by 20% and surface roughness was improved by 30 to 40%. These effects were higher than the coolant with air micro bubble.

Materials Evaluation and Environmental Monitoring Utilizing an Acoustic Resonance

This paper presents the materials evaluation and environmental monitoring techniques utilizing the acoustic resonance, which have been developed by the authors. When the ultrasound passes through thin layer, the transmission and reflection coefficients take their maximum and the minimum values at the resonant frequency. We call this acoustic resonance. The acoustic properties of a polymer film, e.g., the acoustic impedance, ultrasonic velocity, and density, can be determined by observing the acoustic resonance, which occurs at the water/film/reflection plate interface. Acoustic resonance occurs at the reflection plate/film/outer environment interface sensitively changes depending on the outer environment. With use of this, the temperature of the water as an outer environment is tried to be monitored.

Micro Grooving of Cemented Carbide Using PCD Blade

Ultra–Agile Advanced Manufacturing System (U–AMS) has been proposed for an agile prototyping system of research and development, and Super Processing Center (SPC) has been developing as a core machine tool of U–AMS. SPC has high accuracy and rigidity by double column structure based on a vertical precision machining center, hydrostatic oil guides and hydro static/dynamic hybrid oil bearing. In addition, SPC can perform various processing functions by mounting various processing units. Micro grooving by grinding has been researching for one of the SPC unit. PCD blade was developed for micro grooving using SPC. PCD blade was made from PCD disc using wire electrical discharge machining. This paper describes the fabrication method of PCD blade, and the machining characteristics of cemented carbide using PCD blade. In the fabrication method of PCD blade, it was clarified that the cross-sectional shape of PCD blade depended on the feed speed of wire electrode. Micro grooving on cemented carbide surface was performed using developed PCD blade and SPC. As a result, it was confirmed that the micro grooves can be machined using PCD blade, and the width of groove was almost same value as the width of PCD blade. The wear of PCD blade after grooving with 200 grooves was estimated by the depth of grooves. As a result, it was clarified that the wear of PCD blade is approximately 5 μm.