bluuebunny/crossref_metadata_2025 huggingface dataset:
Now You SCC Me, Now You Don’t: Using Machine Learning to Find Stress Corrosion Cracking
Authors: Smith Michael , Blenkinsop Aidan , Capewell Matthew , Kerrigan Brian
Published: January 2021

Electromagnetic Acoustic Transducer (EMAT) is a non-destructive inspection technology that uses guided acoustic waves to detect planar flaws in a metal structure. When deployed via in-line inspection (ILI), it is an effective way to detect cracks in a pipeline. EMAT has thus become a staple of crack management programs throughout the world since its introduction to the market over a decade ago.

As with all technologies, challenges remain with the inspection process. One such challenge with EMAT is classification. While it is possible to determine that a defect is “crack-like” (a property determined by its tendency to reflect incident waves), it is difficult to determine the nature of the defect from the EMAT measurement alone. Indeed, similar reflections are obtained for many different types of defects, from relatively benign manufacturing and construction abnormalities, to more concerning anomalies such as stress corrosion cracking (SCC).

To compensate for the difficulties in classification, it is good practice to follow up an EMAT inspection with a number of in-field verifications. These investigations allow for a more direct observation of classification and size, and provide valuable information about the nature of cracks. They are, however, expensive — meaning that avoiding unnecessary digs is a top priority.

In this paper, we document a developing approach to post-ILI crack management, whereby the results of an EMAT run are combined with those from field verifications to maximize the amount of information gained from costly field work. This approach — which relies on supervised machine learning — leads to a marked improvement in the classification of crack-like indications from EMAT, and allows future investigations to be prioritized according to the likelihood of finding a concerning defect.

The method was trialed on a pipeline system with extensive SCC, leading to an improved success rate in finding SCC, and a more cost effective crack management plan.
Effects of Biaxial Loading on the Tensile Strain Capacity of Girth Welds With Weld Strength Undermatching and HAZ Softening
Authors: Liu Banglin , Wang Yong-Yi , Chen Xiaotong , Warman David
Published: January 2021

The ability to accurately estimate the tensile strain capacity (TSC) of a girth weld is critical to performing strain-based assessment (SBA). A wide range of geometry, material, and loading factors can affect the TSC of a girth weld. Among the influencing factors, an increase in the internal pressure level has been shown to have a detrimental effect on the TSC.

The overall influence of internal pressure is usually quantified by a TSC reduction factor, defined as the ratio of the TSC at zero pressure to the lowest TSC typically attained at pressure factors around 0.5–0.6. Here the pressure factor is defined as the ratio of the nominal hoop stress induced by pressure to the yield strength (YS) of the pipe material. A number of numeric and experiment studies have reported a TSC reduction factor of 1.5–2.5. These studies generally focused on strain-based designed pipelines with evenmatching or overmatching welds, minimum heat affected zone (HAZ) softening, and a surface breaking flaw at the weld centerline or the fusion boundary.

This paper examines the effects of pipe internal pressure on the TSC of girth welds under the premise of weld strength undermatching and HAZ softening. The interaction of biaxial loading and the local stress concentration at the girth weld region was quantified using full-pipe finite element analysis (FEA). The relationship between TSC and the internal pressure level was obtained under several combinations of weld strength mismatch and HAZ softening. Results from the FEA show that the effects of the internal pressure on the TSC are highly sensitive to the material attributes in the girth weld region. Under less favorable weld strength undermatching and HAZ softening conditions, the traditionally assumed reduction factor or 1.5–2.5 may not be applicable. Further, the location of tensile failure is found to depend on both the weld material attributes and the internal pressure. It is possible for the failure location to shift from pipe body at zero internal pressure to the girth weld at elevated internal pressure levels. The implications of the results for both girth weld qualification and integrity assessment are discussed.
Streamlining the GIS to CAD Workflow for Automated Pipeline Alignment Sheet Generation
Authors: Gurung Gyanendra , Roy Kshama
Published: January 2021

The use of Geographic Information System (GIS) in managing pipeline database and automating routine engineering processes has become a standard practice in the pipeline industry. While maintaining a central database provides security, integrity, and easy management of data throughout the pipeline’s lifecycle, GIS enables spatial analysis of pipeline data in addition to streamlining access and visualization of results. One of the major benefits of GIS integration lies in the ease of automating the alignment sheet generation for pipelines. This paper introduces a simplified pipeline alignment sheet generation workflow using GIS datasets to produce highly customizable alignment sheets in AutoCAD, a much-preferred format in the pipeline industry. By utilizing existing GIS and AutoCAD features to generate the alignment sheet, writing complicated geo-processing or plotting algorithms is minimized, which in turn reduces the risks of committing any systematic errors. This robust and user-friendly workflow not only ensures safety but also leads to a cost-effective solution.
Burst Pressure Prediction of Pipes With SCC Colonies: Development of Intelligent Flaw Interaction Rules
Authors: Wang Bo , Liu Banglin , Wang Yong-Yi , Wang Alex , Rapp Steve
Published: January 2021

Stress Corrosion Cracking (SCC) often occurs in clusters or colonies containing anywhere from a few cracks to hundreds of individual cracks. Multiple closely spaced cracks may interact, resulting in a burst pressure lower than what might be expected from a single crack. Most existing flaw interaction rules account for these interactions by using a single interacting crack to represent multiple cracks when the separations between them are less than a critical spacing. The length of this interacting crack is usually the sum of the individual crack length plus the spacing between them. Using this interacting length and the maximum depth in the colony could produce overly conservative burst pressure predictions which can lead to unnecessary hydrotests and/or other remediation actions.

This two-paper series covers the PRCI-funded work aimed at the development of intelligent flaw interaction rules (termed PRCI-CRES SIA-1-5 rules) that can account more accurately the impact of multiple cracks without being overly conservative. This paper focuses on the development of the rules using numerical analyses. A companion paper covers the evaluation of the rules through full-scale burst tests.

The PRCI-CRES SIA-1-5 rules use the principles of equivalent impact among multiple interacting cracks and represent the magnitude of the impact by a single virtual crack. The new rules do not rely on a critical spacing to determine whether there is an interaction. The magnitude of the interaction is a continuous function of the size of adjacent cracks and the spacing between them.

A large number of finite element analyses (FEA) were conducted to examine the interaction among cracks for many crack configurations, including coplanar and noncoplanar cracks with different sizes and spacings. An analysis process was then developed to use the sizes and spacings of all cracks in an SCC colony to predict the equivalent virtual crack size and burst pressure.
Geotechnical Lessons Learned From Nineteen Railway Trenchless Crossings During Construction of a Transmission Pipeline
Authors: Park Jack , Wheeler Lisa , Johnston Katherine , Statters Mike
Published: January 2021

When new pipelines are constructed, they often cross existing major infrastructure, such as railways. To reduce potential service disruption, it is a common practice to complete these crossings using trenchless technologies. Without proper methods and oversight in planning and construction, there may be serious safety and financial implications to the operators of the railways and the public due to unacceptable settlement or heave. If movement tolerances are exceeded, the schedule and financial loss to the railway operators could be in the millions of dollars per day.

Recent construction of a new pipeline across the Canadian prairies implemented ground movement monitoring plans at 19 trenchless railway crossings in order to reduce the potential for impact to the track and railway operations. The specifics of the plan varied for each site and were based on the expected ground conditions, as well as permit requirements from the various railway operators, but typically included ground movement monitoring surveys, observation of the cuttings, recommendations for a soil plug at the leading edge of the bore casing, and frequent communication with both the railway operators and the contractors. For all crossings, the expected soil and groundwater conditions were obtained from pre-construction boreholes and confirmed during excavation of the bore bays. Based on the expected ground conditions, appropriate soil plug lengths, if required, were recommended. In general, fine-grained clay/silt-dominated soils needed minimal to no soil plug in order to minimize the potential for ground heave, while coarser-grained sand-dominated soils needed a longer soil plug in order to reduce the potential for “flowing soil” which would cause over excavation along the bore path. Prior to boring, surface monitoring points were established along the tracks to monitor for changes in the ground surface elevation. Additional subsurface points were installed for crossings where the potential for over excavation was higher. These monitoring points were surveyed before, throughout, and following completion of construction, and the frequency of the surveys was increased when the movement was nearing or exceeding specified tolerances. The effort to monitor and reduce the potential for ground movement was a coordinated effort between the geotechnical engineers, railway operators, and construction contractors.

The purpose of this paper is to present the lessons learned from the 19 trenchless railway crossings, including the challenges and successes. Recommendations for ground movement monitoring are also provided to help guide railway operators, design and geotechnical engineers, and contractors during the construction of future trenchless pipeline crossings of railway infrastructure.
Full Scale Test Validation of Fatigue Crack Growth Rate of Flaws in ERW Pipe
Authors: Tiku Sanjay , Ghovanlou Morvarid , Dinovitzer Aaron , Piazza Mark , Jones T. A.
Published: January 2021

While the general fracture mechanics principles and methodologies for calculating fatigue lives are well documented and validated, their application in the prediction of pipeline system fatigue lives differed from field experience. The source and magnitude of the conservatism inherent in the calculated fatigue life estimates are an important element when establishing integrity management programs. Of particular interest are the fatigue life estimates used in integrity management programs for electric resistance welded (ERW) pipeline systems that may have pipe seam anomalies oriented along the pipe axis. BMT Canada Ltd (BMT) was contracted by Pipeline Research Council International (PRCI) to develop a pipeline material fatigue crack growth database and conduct full scale cyclic pressure fatigue tests to develop improved crack growth rate parameters.

A pipeline material fatigue crack growth database was developed using 185 fatigue crack growth rate tests on 45 pipeline materials ranging in grade from X46 to X70 and in vintage from 1937 to 2014. The database included fatigue crack growth rate tests on 18 pipe body base materials (BM) and 27 ERW weld seam materials at two different, stress ratios (R), of R-ratio = 0.1 and R-ratio = 0.6. The sampled crack growth rates observed in the pipeline steels, tested in the project were 2 to 3 times lower than the crack growth rates recommended in BS 7910. This paper presents the proposed power (Paris) law fatigue crack growth equation parameters, C and m, developed in the study.

Two full-scale cyclic pressure tests were carried out to validate the use of recommended crack growth rate parameters. Axial flaws were machined in the pipe body and weld center line (WCL). Fifty-one (51) flaws of different lengths and depths were machined. The crack growth rates were monitored during the cyclic pressure tests by recording crack mouth opening displacement (CMOD). The calibration curves for correlating CMODs with crack depths were developed and validated against finite element (FE) analysis. The fatigue crack growth rates observed in the full-scale tests were then compared with existing BS 7910 and API 579 formulations.

The comparison confirmed that the BS 7910 approach results in very conservative estimates of fatigue crack growth rates for axial flaws. The BS 7910 stress intensity factor formulation overestimated the bulging correction for axially oriented flaws. The API 579 fracture mechanics-based fatigue crack growth formulation combined with crack growth rate parameters developed in this program provided improved estimates for fatigue life. The fatigue crack growth rates for line pipe and ERW weld seams developed in this project were shown to be less conservative and better predictors for fatigue crack growth and represent a valuable tool for pipeline integrity management. The use of this information will enable pipeline operators to focus remedial actions on features that have the lowest estimated fatigue lives.
Dent Assessment and Management: API Recommended Practice 1183
Authors: Dinovitzer Aaron , Tiku Sanjay , Piazza Mark
Published: January 2021

Pipeline dents can be developed from the pipe resting on rock, a third-party machinery strike, rock strikes during backfilling, amongst other causes. The long-term integrity of a dented pipeline segment is a complex function of a variety of parameters including pipe geometry, indenter shape, dent depth, indenter support, secondary features, and pipeline operating pressure history at and following indentation. In order to estimate the safe remaining operating life of a dented pipeline, all of these factors must be considered and guidelines for this assessment are not available.

US DOT regulations (49 CFR 192 and 195) include dent repair and remediation criteria broadly based upon dent depth, dent location (top or bottom side), pressure cycling (liquid or gas), and dent interaction with secondary features (weld, corrosion, cracks). The criteria defined above are simple to use, however, they may not direct maintenance to higher risk dent features and be overly conservative or, in some cases, unconservative.

PRCI, USDOT, CEPA and other full-scale testing, finite element modelling and engineering model development research has been completed to evaluate the integrity of pipeline dents. These results have demonstrated trends and limits in dent behavior and life that can improve on existing codified and traditional treatment of dents. With these research results a guideline for dent management can be developed to support operators develop and implement their pipeline integrity management programs.

This paper provides an overview of the newly developed API recommended practice for assessment and management of dents (RP 1183). The RP considers dent formation strain, failure pressure and fatigue limit states including the effects of coincident features (i.e. welds, corrosion, cracks and gouges). This paper will focus on how pipeline operators can derive value from this step change in integrity management for dents. The paper describes the basis for the dent screening and integrity assessment tools included in the RP. This RP provides well founded techniques for engineering assessment that may be used to determine the significance of dent features, if remedial actions are required and when these actions should be taken.
A Comparison of Remote Sensing Techniques for Centreline and Weld Mapping in Place of Manual Survey in Hazardous Environments
Authors: Hlady Joseph , Sands Dana , Fugate Lance
Published: January 2021

Many places where pipelines are built have soil, basal material and water table conditions which can create suboptimal environments for centerline as-builting and weld mapping. Furthermore, ditches containing multiple pipelines can make as-built and weld mapping particularly complex especially when the pipes are of varying sizes. The complexity of the laying in of multiple pipes may also result in the ditch being exposed longer than desired, enabling further deterioration of ditch conditions and even flooding. At times, circumstances can become so hazardous that manual survey of the pipeline centerline can only be completed while the pipe is outside of the ditch (requiring a transposition) and a variety of survey techniques must be used to capture the centreline locations. Surveying at a distance from the pipes can make verification to weld mapping and field inspection problematic. Recent advancements in remote sensing, particularly mobile LiDAR and imagery collection technology, have lowered collection and processing costs and expanded the applicability of the technology to complex collection environments and harsh conditions on pipeline construction rights-of-way. Additionally, there has been a marked improvement in overall data accuracy and precision from mobile mapping systems. Up until recently, these technologies have only been useful in static construction environments where periods of inactivity during construction afforded the time to set up and collect data in a safe and accurate manner. New remote sensing systems, designed for more rugged, fast-paced, and complex environments are expanding the use of mobile remote sensing to the pipeline construction right of way. These mobile mapping technologies have significant advantages over drone collected data particularly with respect to the logistics of the data collection. Recently, advanced mobile mapping technology was employed on various pipeline construction projects and the accuracy of LiDAR and imagery collection for centerline as-builting and weld mapping was assessed. Some of the project locations were in areas where the traditional manual collection of data could be deemed hazardous or unsafe. This paper evaluates the collection technique against the traditional methods used under hazardous or inaccessible conditions and discusses the benefits of mobile remote sensing for this scenario. The authors also provide an analysis of the remote sensing based as-built and weld mapping data against those acquired through the traditional technique during this trial. Opportunities for adoption of this method as well as improvements to its application are also discussed.
Identification and Mitigation of a Landslide Threatening Four Operating Natural Gas Pipelines
Authors: Ahmadipur Amir , McKenzie-Johnson Alexander , Ebrahimi Ali , Rice Anthony H.
Published: January 2021

This paper presents a case study of a landslide with the potential to affect four operating high-pressure natural gas pipelines located in the south-central US state of Mississippi. This case study follows a landslide hazard management process: beginning with landslide identification, through pipeline monitoring using strain gauges with an automated early alert system, to detection of landslide movement and its effects on the pipeline, completion of a geotechnical subsurface investigation, conceptual geotechnical mitigation planning, landslide stabilization design and construction, and stress relief excavation. Each step of the landslide hazard management process is described in this case study.
Plastic Constraint-Matched Pin-Loaded SENT Specimen for Fracture Analysis of Radially Growing Longitudinal Cracks in Thin-Walled Piping
Authors: Furmanski Jevan , Sarosi Peter , Marzinsky Cary , Carpenter Don , Thirumalai Neeraj
Published: January 2021

In recent years increased attention has been given to the transferability of standardized fracture test data to thin-walled pressurized equipment. For smaller diameter piping, for example, standard test specimens loaded in “hoop” tension are not possible due to pipe curvature and thinner wall thickness (often less than 1/3 inch). Further, it is not clear that standardized fracture specimens produce transferrable results to the seam weld fracture problem due to low plastic constraint, which is exacerbated in thin wall pipe. Single-edge notched tension (SENT) specimens were fabricated by extracting a segment pipe wall and finishing to a parallel piped incorporating nearly all the wall thickness. These segments were electron beam welded to low carbon steel grip ends to produce only localized heat affected zone without affecting the test section. The result is a nearly ideal pin-loaded SENT specimen for radial fracture testing. This geometry was evaluated with 2D and 3D nonlinear finite element analysis in Abaqus, and plastic constraint matching was evaluated compared to a thin-walled pipe under internal pressure with a radially growing crack. A nearly ideal plastic constraint match between the pin-loaded SENT and radial seam weld crack was confirmed up to about 500 psi-in, which is substantially beyond a typical JIc in the X52 steel used in the analysis. Thus, pinned SENT testing is recommended for evaluation of radial fracture in thin-walled piping.
Study on Non-Axisymmetric 3D Curved Surface Turning by Driven-Type Rotary Tool Synchronized With Spindle
Authors: Ishizuka Akane , Nakagawa Kensuke , Morimoto Yoshitaka , Hayashi Akio , Kaneko Yoshiyuki , Suzuki Naohiko , Hirono Ryo
Published: January 2021

Since shifting to electric vehicles as a countermeasure against global warming is hard to complete, the hybrid car has been considered as another possible solution. However, based on the calculation of total CO2 emissions, all hybrid cars which will constitute 90% of all cars are expected to be equipped with an internal combustion engine even after 2030. Therefore, further efficiency improvement of the internal combustion engine is necessary. One of the key factors is the variable valve timing and variable lift of the cam mechanism. Since conventional technology uses a complicated link mechanism and servo motor control, this creates a problem to build small cars or two-wheeled vehicles because they are not big enough for the size and weight of the two important parts: the variable valve timing and variable of cam mechanism, which won’t fit. To solve this problem, a cam shape with a three-dimensional curved surface has been proposed. In order to create this shape, the machining method for non-axisymmetric curved surface turning (NACS-Turning) is required. To build the new system, our research group has proposed a new machining method using a driven rotary tool and a linear motor driven moving table to enable to achieve NACS-Turning. In this new system, a new tool rotation axis (B axis) is adopted to synchronize its rotation position with the rotation position of the spindle (C axis) holding the workpiece and the X1-, X2-, and Z-Axis positions in total. In this paper, the new hardware configuration is proposed to overcome the present machining accuracy from the point of non-circular machining method.
Investigation of Crystallographic Aspects of Subsurface Damage Induced by Grinding Using Micro-Raman Tomographic Imaging
Authors: Onuki Teppei , Kan Shunsuke , Lin Wangpiao , Lu Wentong , Hasegawa Kousuke , Ojima Hirotaka , Shimizu Jun , Zhou Libo
Published: January 2021

The objective of this study is to propose and develop an evaluation method on the process damages of sapphire wafers, regarding crystallographic aspects of the damages by use of tomographic imaging techniques with laser Raman microscopy (called as micro Raman tomographic imaging: mRTI). In this paper, tomographic images with the peak width and the shift of the peak position were observed with mRTI, on c-plane cut sapphire wafers along a-plane, with micro fractures induced by brittle-mode grinding. Fractures along m-plane from the surface to 2–7 microns-depth, and fractures along r-plane from the bottom end of the m-plane fracture to 14 microns-depth, subsequently induced elastic strain field around the fractures, could be visualized without destructions of the wafers.
Achieving Highly Stable Removal Rate in Small Tool Polishing of Glass Lenses
Authors: Satake Urara , Enomoto Toshiyuki , Miyagawa Teppei , Ohsumi Takuya
Published: January 2021

The demand for improving the image quality of cameras has increased significantly, especially in industrial applications, such as broadcasting, on-vehicle, security, factory automation, and medicine. Surface of glass lenses, which is a key component of cameras, is formed and finished by polishing using small tools. However, the existing small tool polishing technologies exhibit serious problems including an unstable removal rate with the accumulated polishing time. In concrete, low removal rate at the beginning of the polishing process and sudden decrease in the removal rate during the polishing process significantly deteriorate stability of the removal rate.

To improve the stability of the removal rate, we proposed a vibration-assisted polishing method using newly developed polishing pads with titanium dioxide particles in the previous work. Polishing experiments on glass lenses confirmed that the variation in the removal rate was suppressed by the developed polishing method; however, the reason for the improvement, in concrete, the relation between the vibration of polishing pressure and the stability of the removal rate remains unknown.

In this study, we investigated and clarified the effect of the vibration of polishing pressure on the surface conditions of polishing pads, which strongly affected removal rate.
Fabrication of Novel Microvalves Driven by Heat From Magnetic Nanoparticles
Authors: Miwa Daiki , Sakurai Junpei , Hata Seiichi , Oka Chiemi
Published: January 2021

The present paper proposes novel microvalves remotely controlled without electrical wiring on each valve. The proposed microvalves are controlled utilizing heat from magnetic nanoparticles in an alternating magnetic field. A procedure for fabrication of the microvalves was established. the fabricated microvalves operated on a hotplate.
Investigation of Cutting Force in Screw Cutting by Three Axis Controlling Helical Interpolate With a Wireless Communication Tool Holder System
Authors: Matsui Shota , Ozaki Nobutoshi , Hirogaki Toshiki , Aoyama Eiichi , Matsuda Ryo
Published: January 2021

In recent years, the movement of machine tools including 5-axis control machining centers (5 MC) and turning centers has progressed to enable machining at high speeds and high degrees of accuracy. The accuracy of simultaneous three-axis movement at very high feed speeds has increased significantly. Specifically, with the development of control technologies for these machine tools featuring simultaneous three-axis control, the accuracy of helical interpolation motion at high feed speed has achieved a sufficient level to perform processes such as screw cutting with a thread mill tool. Boring machining and pocket machining for difficult-to-cut materials are processing methods that employ helical interpolation movements with an endmill tool, and it is becoming a promising technology in light of recent advancements. Therefore, we looked at screw cutting with a thread mill tool and proposed a novel monitoring method to improve the accuracy of machining the screw by deriving the radial force of thread cutting from three components — two forces in the X and Y directions and torque around the Z axis — using a piezoelectric dynamometer. In this study, we also investigated the accuracy of machining the screw when the pilot hole and screw were drilled at the same time as well as the accuracy when the pilot hole is drilled beforehand. In addition, we monitored the cutting data and X-Y feed motions using a wireless holder and CNC information to construct a smart manufacturing method for machining screws using helical interpolation. As a result, the proposed monitoring method is effective at improving the accuracy of machining screws from various work materials using helical interpolation motion of a thread mill tool.
Removal Machining Performances by Using Inert Gas Filled Micro Bubble Coolant
Authors: Iwai Manabu , Yamashita Ryouta , Anzai Satoshi , Ninomiya Shinichi
Published: January 2021

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.
Development of Tool Steel Matrix Composites With High Thermal Conductivity
Authors: Sasaki Gen , Choi Yongbum , Sugio Kenjiro
Published: January 2021

The improvement of thermal conductivity of tool steel is a very important problem to achieve life prolongation of a metal die used in press forming and die-casting and obtain large size or complex shape products with good mechanical properties. To improve the thermal conductivity without the degradation of mechanical properties, some kind of dispersants were added into tool steel 40CrMoV5 in ISO standard. 0.5–1.0 vol. % carbon nanofiber, 4–8 vol. % TiB2 particles with 2.62 micrometer in average diameter and 8 vol. % Cu particles was added in tool steel. Dense composites were fabricated by spark plasma sintering by controlling sintering temperature and time. The thermal conductivity was improved by adding all dispersant. Strength of carbon nanofiber / steel composites increased by adding 0.5 vol. % fiber, but decreased by adding 1.0 vol. % because of aggregation of carbon fiber. Some chemical reaction occurred in TiB2 particles/ steel composites, and the elongation improved because of the boron element in the interface. Cu /steel composites keep good strength compared with monolithic tool steel and the thermal conductivity increased dramatically as increasing Cu contents.
Monitoring of Tool Wear Distribution With Cutting Force Measurement in Drilling
Authors: Tamura Shoichi , Sekigawa Kodai , Matsumura Takashi
Published: January 2021

In the automated machining processes, tool damage should be managed to assure product qualities, promote machine tool performance and reduce production time and cost. In drilling process, the cutting process changes along the cutting edge; and the tool wear is not uniform. This paper presents a monitoring of the tool wear distribution with measuring the cutting force in drilling with a twist drill. The cutting force increases with the cutting area in the edge penetration into workpiece in drilling. In the proposed approach, the cutting edges are divided into small discrete segments. The increasing rate of the cutting force at a segment is associated with the normal forces loaded at the cutting area. The normal force distributions, then, are estimated for the cutting edge damage. The widths of flank wear lands along the cutting edge is monitored based on the increase of the normal force distribution. The cutting tests were conducted to validate the presented approach with measuring the cutting force in drilling of carbon steel. The presented approach estimates the tool wear distribution on the edge with the cutting time. The average stress distribution loaded on the flank wear land is also estimated in the regression analysis.
Analysis of the Effect of Machining Sequence on Machining Error Considering Workpiece Rigidity Change
Authors: Nakao Yutaro , Teramoto Koji
Published: January 2021

The objective of this research is to investigate relations between individual physical phenomena and machining error from the measured machined error.

Small lot production using numerical control machine tools is widely applied to high quality and high value-added products. In such production, agile and flexible machining is required. Thus, there have been many researches which investigate the effect of specific phenomena such as cutting force, thermal expansion, tool wears, chattering vibration and so on, which is to realize high precision machining. However, there have been some unsolved problems. The first problem is focused phenomena are mostly cutting force and/or machine tool deflection. Accordingly, other effects such as the results by workpiece rigidity change have not been investigated enough. The second problem is that the generation process of machining error is complicated and there is no proper method to compensate. Because of those complicate process, it is difficult to determine the dominant error factor of a new machining case in advance.

Therefore, on-machine error measurement and estimation of error factors are essential technologies in order to achieve accuracy assurance. Recently, machining for rib-structured and thin-walled workpiece becomes important because of their higher structure efficiency and light weight characteristic. In this paper, the effect of workpiece rigidity to the machining error is investigated. Depend on the machining sequence, workpiece rigidities change differently during the machining process. Two different machining cases with different machining sequences are conducted and difference between the cases are investigated.
Basic Study on Polishing Technology for Microcavity With Electrically Controlled Slurry
Authors: Hayama Yuka , Kakinuma Yasuhiro
Published: January 2021

Optical microcavity, which can localize light at a certain spot for a short period of time, have a wide range of applications, such as optical signal processing and optical frequency combs. Single crystal calcium fluoride is one of the most suitable material for fabricating optical microcavity due to its excellent optical properties; however, it cannot be manufactured by chemical processes such as etching due to its crystal anisotropy. Currently, high performance optical microcavities are fabricated by ultra-precision turning followed by a hand polishing process because it has complex shape with a size of micro order. However, hand polishing deteriorates the shape made by ultra-precision turning and has a low reproductivity. Therefore, a development of a soft mechanical polishing method to replace hand polishing is strongly desired. Electrically controlled slurry technique is a promising approach in polishing of microparts, where AC electric field is applied to the slurry in order to control the distribution of abrasives to improve the polishing properties in free abrasive polishing. In this study, polishing by applying electrically controlled slurry was conducted for microcavity and the influence of frequency and applied voltage were investigated. From the experimental results, clear differences in the surface quality of microcavity were shown according to amplitude of AC voltage and its frequency.
The Influence of Defects in ta-C Coating Deposited by FCVA Method on Their Tribological Behavior
Authors: Lee Woo-Young , Jang Young-Jun , Tokoroyama Takayuki , Murashima Motoyuki , Umehara Noritsugu
Published: January 2021

Diamond like-carbon (DLC) coatings is a form of amorphous consisting of sp2-bonded and sp3-bonded phase. Among the DLC series, DLC coatings containing a large percentage of sp3 ratio, referred as tetrahedral amorphous carbon (ta-C) coatings, have attracted significant attention as protective coatings in various fields such as tribological applications and automobile components that demand superior durability, chemical inertness and low friction at high temperature. Particularly, the filtered cathodic vacuum arc (FCVA) technique with an energetic plasma can deposit the ta-C coating, but it has a drawback such as decreasing deposition rate and occurring macroparticles. Research on morphological and structural change of defects in ta-C coatings fabricated by FCVA is important for understanding their wear and friction behavior. In this study, the types of defects presented on a ta-C coating were classified as spike, droplet and pore with their morphology, structural and mechanical properties. The tribological behavior of the coating was characterized by ball-on-disk test using a Si3N4 ball at a testing temperature of 170 °C. In order to confirm the effect of defects in the ta-C coating on the tribological behavior, the defects in a designated area were investigated as a function of different sliding cycles. Initially, a running-in cycle is maintained until 2,000 cycles, following which a steady-state value of 0.1 is observed from sliding cycles of 2,000 to 10,000. At the end of 10,000 cycles, the wear rate of the ta-C coating is 4.3 × 10−6 mm3/Nm. Structural changes among the defects are apparent on droplet and pore after the friction test at 170 °C. The nodular defects including spikes and droplet is grinded off on top surface of that and is retained until 1,000 cycles. In steady state up to 6,000 cycles, droplet was survived, on the other hand, the spikes are almost polished from sliding.
Wear Resistant DLC Coatings for Soft Metallic Materials
Authors: Yamaki Takanori , Osawa Takuya , Matsuo Makoto , Akasaka Hiroki , Tanaka Shinji , Kikuchi Masao , Hirata Yuki , Ohtake Naoto , Yamamoto Hiroshi
Published: January 2021

In sliding parts used by construction machines which is operate in harsh environment, one of the problems is that abnormal wear and seizure occur due to sliding under dusty condition. That severe wear is caused by sand dust intervening on the sliding surface. In order to prevent severe wear and seizure, a combination of an iron-based material and a soft metallic material such as brass is used on the sliding surface. And more,, we applied DLC (diamond-like carbon) coating on the surface of soft metallic materials. Specifically, we deposited segment structured DLC film on copper alloy, and evaluated its tribological characteristics by reciprocating sliding test. As a result, segment structured DLC coatings on soft metallic material showed more than three fold high wear resistance and seizure resistance as compared with DLC coated SUS440C, when dust is mixed in lubricant.
Proposing a New Evaluation Method in Si Wafer Rotary Grinding
Authors: Kusuyama Jumpei , Kawase Bima , Nakao Yohichi , Kanazawa Masaki , Ishikawa Kazumasa
Published: January 2021

Although there have been several studies on machining of semiconductor materials, most of them are concerned with abrasive finishing (such as chemical-mechanical polishing, mechanical polishing and lapping), and only a few have reported on optimizing rotary grinding conditions (such as the grinding wheel rotational speed, wafer rotational speed, wheel diameter, wafer diameter, and feed rate). In this study, to gain further insight, we define a dimensionless number and use it to evaluate our experimental results. This dimensionless number — called the “grain approach angle” — is the ratio of the grain running length of the machined wafer surface and the depth of cut due to grain during the grain running time. For this study, our evaluation coefficients are taken to be surface roughness, grinding force, and grinding ratio. We found it more suitable to use the grain approach angle rather than a previously defined dimensionless number (which was evaluated as the ratio of the wheel rotational speed to the wafer rotational speed). We also found that, by using the grain approach angle, trends in surface roughness exhibited invariant similarities under varying conditions.
Resistance Spot Welding in Non-Combustible Magnesium Alloy
Authors: Shao Xuanyi , Miyashita Yukio , Panwised Duriyathep , Borrisutthekul Rattana
Published: January 2021

Resistance spot welding (RSW) was applied to non-combustible magnesium alloy, AX41 (Mg-4%Al-1%Ca) to investigate its weldability. The similar material joint of AX41 and dissimilar materials joint between AX41 and aluminum alloy, AA6061 were welded. Tensile shear test was carried out to evaluate joining strength in the similar and dissimilar materials RSW joints. In case of similar material joints, the maximum load obtained with tensile shear test in AX41 similar material joint was higher than that obtained in AA6061 similar material joint. Moreover, higher maximum load was obtained in a similar material joint without surface polishing compared to joint welded with surface polishing in AX41. In case of the dissimilar materials joint, the maximum load obtained was almost comparable with AX41 similar material joint, however scatter in joint strength was large. Weldability of the dissimilar materials joint became poor by applying surface polishing.
Experimental and Analytical Resin Impregnation Characterization in Carbon Fiber Reinforced Thermoplastic Composites
Authors: Kobayashi Satoshi , Osada Toshiko
Published: January 2021

Effect of molding condition on resin impregnation behavior and the associated mechanical properties were investigated for carbon fabric reinforced thermoplastic composites. Carbon fiber yarn (TORAYCA, Toray) was used as a reinforcement, and thermoplastic PI (AURUM PL 450 C, Mitsui Chemicals) was used as the matrix. CFRTP textile composites were compression-molded with a hot press system under the molding temperature, 390 °C, 410 °C and 430 °C, molding pressure 2 MPa and 4 MPa and molding time 0∼300 s. In order to evaluate the impregnated state, cross sectional observation was performed with an optical microscope. Specimen cross-section was polished and finished with alumina slurry for a clear observation. The images observed were processed through image processing software to obtained impregnation ratio which defined as the resin impregnation area to the cross-sectional area of a fiber yarn. Resin impregnation was accelerated with molding temperature and pressure. At molding temperature more than 410 °C, resin impregnation was similar irrespective of temperature. Tensile test results indicated that modulus and strength increased with resin impregnation. Resin impregnation during molding was predicted using the analytical model based on Darcy’s law and continuity condition. The analysis could successfully predict the impregnation behavior despite the difference in molding pressure and temperature.
The Development of New Turning Tool for Cryogenic Machining
Authors: Wang Yongqing , Liu Haibo , Gan Yongquan , Han Lingsheng , Liu Kuo , Ban Ziyou
Published: January 2021

Cryogenic manufacturing processes have emerged as environmental-friendly, increase tool life and improve surface integrity of machined components by efficiently removing the heat from the cutting zone. Especially considered to be an efficient method to machine difficult-to-cut metals which are poor thermal conductivity, such as nickel, titanium alloys and polymer materials and so on. Many researchers have studied the effectiveness of cryogenic machining process, such as increasing tool life and improving surface integrity and so on. However, most articles on this topic were not considered the applications of actual industry. Cutting tool is one of the most important parts of industry applications. Most of cutting tools were not designed for cryogenic machining. In this work, the internally cooled turning tool was developed for cryogenic machining. The spray angle and diameter of the outlet were optimized by thermal field simulations. The results showed that 15° injection angle was more suitable to the machining process. Compare to 1mm outlet diameter, 3mm outlet diameter had better cooling effect. And the shape of outlet was optimized. A pressure simulation of the inner channel is carried out. The result shows that the pressure drop from inlet to outlets is only 66.696277Pa (about 6‰). Then, a spray test of the cutting tool was performed. The tests revealed that liquid nitrogen could be transmitted accurately and stably to the tool nose and the machining area. At last, a machining experiment proved that the turning tool could reduce the cutting temperature effectively when machining Ti-6Al-4V.
Performance Analysis of Multi Wall Carbon Nanotubes (MWCNT) Coated Tool Electrode During Machining of Titanium Alloy (Ti6Al4V)
Authors: Shirguppikar Shailesh , Patil Maharudra
Published: January 2021

Electric Discharge Machining (EDM) is one of the leading non-conventional machining processes used to machine hard-to-cut materials in wide range of industrial, biomedical, automotive, defense and aerospace applications. EDM is a controlled spark generation process, which is usually used for machining of difficult to cut materials. In this study, experiments were performed on Titanium Alloy (Ti6Al4V) using thin-film multi-wall Carbon Nanotubes (MWCNT) coated electrode and uncoated aluminum electrodes. Morphological and structural investigations of MWCNT coating were performed using Scanning transmission electron microscope (TEM) and Raman spectroscopy. All experiments were designed with Taguchi’s L16 orthogonal array. Each experiment performed under different condition of current, gap voltage and pulse on time. MRR, TWR, SR and OC are studied for each experiment. It was observed that MWCNT coated electrode gives better surface roughness, higher material removal rate, and lower tool wear rate. The experimental result showed that MRR increased by 14.15%, tool wear rate decreased by 23.40%, surface roughness reduced by 22.14 % and overcut reduced by 23.43 % respectively as compared to uncoated aluminum electrodes. All performance responses improved with thin-film MWCNT coated electrode due to magnificent electrical conductivity and chemical stability of CNT. Analysis of Variance (ANOVA) carried out to understand significant process parameters and its contribution in mentioned response variables. Multi-Wall CNT shows better results at high temperature and prevents the tool wear rate. The surface roughness of Ti6Al4V improved with MWCNT coated electrode and it was evident with scanning electron microscope (SEM) images of workpiece. Comparative study of coated and non-coated gives new development of novel electrode tool for electric discharge machining processes.