Idiopathic inflammatory myopathies cause progressive muscle weakness and degeneration. Since high-dose glucocorticoids might not lead to full recovery of muscle function, physical exercise is also an ...important intervention, but some exercises exacerbate chronic inflammation and muscle fibrosis. It is unknown how physical exercise can have both beneficial and detrimental effects in chronic myopathy. Here we show that senescence of fibro-adipogenic progenitors (FAPs) in response to exercise-induced muscle damage is needed to establish a state of regenerative inflammation that induces muscle regeneration. In chronic inflammatory myopathy model mice, exercise does not promote FAP senescence or resistance against tumor necrosis factor-mediated apoptosis. Pro-senescent intervention combining exercise and pharmacological AMPK activation reverses FAP apoptosis resistance and improves muscle function and regeneration. Our results demonstrate that the absence of FAP senescence after exercise leads to muscle degeneration with FAP accumulation. FAP-targeted pro-senescent interventions with exercise and pharmacological AMPK activation may constitute a therapeutic strategy for chronic inflammatory myopathy.
The influence of Si and Al additions to 0.55 mass% C steel on machinability is discussed in cutting with a fly tool of TiAlN coated high speed steel, as performed in gear cutting. Three model steels ...are prepared with controlling nearly the same hardness to study the effects of the alloying elements: one reference steel with C as the only alloying element (Base steel), and two steels alloyed also with 1 mass% Si or Al. The cutting tests are performed to obtain the cutting forces, observe the cutting chips and analyze the damage on the rake faces of the tools. The orthogonal cutting data in the cutting force simulation are identified to minimize the discrepancies between the measured and the simulated forces for the tested steels. When cutting the Base steel, few adhered materials form and the coated thin layer is worn mainly by abrasion. When cutting the Si alloyed steel, the coating surface is covered by adhered layers containing Si–O, Fe2SiO4 and FeO, which contribute to the lowest friction and protect the coated thin layer from wear. When cutting the Al alloyed steel, an Al2O3 layer forms on the coating. The Al2O3 layer induces high friction, large cutting forces and cutting heat, resulting in the rapid substrate softening and coating fracture.
Cutting technologies have been widely applied in the manufacturing of airplane, automobile, medical, energy, and information industries. Cutting operations are generally evaluated in terms of ...material removal rates and surface quality. Materials science and engineering has also made significant progress in improving material properties. Therefore, scientific research should be conducted to achieve high performance when working with difficult-to-cut materials such as nickel-based super alloy. Because the manufacturing of products with complex shapes in various industries requires multi-axis machining, the cutting operations should be managed efficiently through controls, simulations, and monitoring.
This special issue was organized by Research Committee of Cutting Technologies in Japan Society for Precision Engineering. This issue includes 14 papers on advanced cutting technologies covering the following topics:
- Modeling the tribological aspects of the tool face–workpiece interface during the cutting process.
- Cutting mechanics in advanced cutting operations.
- Tool wear and coolant supply in cutting of advanced materials.
- Cutting processes for hard materials to improve cutting performance.
- Fixturing, chatter suppression, and tool path generation to control cutting processes and operations.
- Surface characterization and modeling to control product quality in multi-axis machining.
I hope this issue will be helpful for readers to understand cutting processes and improve the cutting operations.
Machinability of steels containing different carbon contents is evaluated in cutting with a fly tool of TiAlN coated high speed steel, as performed in gear cutting. In order to investigate the effect ...of carbon content on the cutting process, 0.2, 0.4 and 0.6 mass% C steels are prepared with controlling nearly the same hardness. The cutting tests are conducted to measure the cutting forces, observe the chip formations and analyze the damage on the rake and flank faces of the tools. The machinability of the tested steels is compared each other in terms of the cutting model in the cutting force simulation. The orthogonal cutting data are identified to minimize the discrepancies between the measured and the simulated forces. The shear stress on the shear plane becomes large at high carbon contents, and thus the cutting force increases with the carbon content. On the rake face of the tool, substrate softening and cracking in the coated thin layer occur in a certain cutting length. In cutting of the 0.6 mass% C steel, the cracks initiate rapidly in the coated thin layer on the rake face due to large cutting forces and cutting heat. Small flank wear is observed in the cutting of 0.2 and 0.4 mass% C steels, while in the 0.6 mass% C steel thermal wear with adhesion is promoted at high cutting temperatures.
Non-step drillings of deep holes with twist drill are required to achieve high production rates in machine shops. However, tool breakage sometimes occurs due to chip clogging in the holes. The ...surface finish is also deteriorated by chip scratching. These machining troubles are induced by the change in the chip flow accompanied by tool wear progress. This paper discusses the cutting process in drillings of deep holes in terms of the geometrical change in the cutting edge with the tool wear. The chip flows towards the radial direction with the change in the edge shape when the tool wear increases. Then, the chip clogging in the hole induces a large oscillation in the cutting force. The chip flow is also analyzed with the change in the edge shape due to the tool wear by the energy-based force simulation.
Recently, manufacturing technologies have progressed owing to high industrial demand. For example, in the automobile and aircraft industries, manufacturing processes require technologies that allow ...for high machining rates of lightweight and/or difficult-to-cut materials. Fabricating medical equipment involves the machining of biocompatible materials with high mechanical strength. Information devices require high-quality ultraprecision manufacturing processes. Furthermore, measurement and characterization technologies are also essential for manufacturing. Along with the evolution of manufacturing technologies, scientific studies have been performed on manufacturing phenomena and process control based on physical and/or mathematical aspects. This special issue was promoted by the International Conference on Leading Edge Manufacturing/Materials & Processing (LEM&P2023) held from June 12, 2023 to June 16, 2023 at Rutgers University in New Brunswick, sponsored by the Japan Society of Mechanical Engineers. This conference was co-located with the Manufacturing Science Engineering Conference (MSEC), ASME, and North American Manufacturing Research Conference (NAMRC), SME. This special issue includes nine papers that describe the innovations and detailed progress in the following areas: - Characterization of materials - Fundamental study and modeling of material removal process - Manufacturing control and optimization - Manufacturing processes for new hard materials - Micro-/Nano-scale manufacturing - Tool manufacturing and performance - Metrology and evaluation - Surface characterization This special issue includes technical and scientific discussions that suggest new key technologies for future manufacturing. We hope that this will help readers understand manufacturing processes and improve their operations. We thank the authors and reviewers for their generous cooperation and the editing staff for their contributions.
Cutting technologies are utilized in many industrial sectors, such as automobile, aircraft, and medical-device manufacturing as well as dies and molds. Thus, the requirements for higher geometric ...accuracy, better surface integrity, and longer component service lifetimes have substantially increased. In addition, maintaining high machining efficiency while simultaneously reducing power consumption and CO
2
emissions during machining is important for sustainable development.
This special issue features 11 papers on the most recent advances in cutting technologies for metals and composite materials.
- Reverse finishing characteristics of drilling surfaces
- Machining error simulation for end milling
- Visualization of cutting phenomena using a single-crystal diamond tool
- Milling of TiB
2
particle-reinforced high-modulus steel
- Electrodischarge-assisted turning of carbon fiber-reinforced polymers
- Suppression of chatter vibration during double-insert turning
- Prediction of surface roughness components during turning
- Microtome blades for high-precision tissue sectioning
- Boiling of coolant near the cutting edge in high-speed machining
- Residual stress during drilling of aluminum alloy
- Effect of strain hardening on burr control during drilling
This issue provides an understanding of recent developments in cutting technologies, aiming to inspire further research in this field.
We deeply appreciate the careful work of all the authors and thank the reviewers for their diligent efforts.
A novel cutting manner is presented to control regenerative chatter vibration in double inserts cutting, in which the forward and the backward inserts cut workpiece simultaneously with phase ...difference in the modulation of finished surface. In double inserts cutting, the forward insert is clamped above the backward insert. Both the inserts are positioned symmetrically with a height offset with respect to the workpiece rotation center. The forward insert mainly removes the material; while the backward insert cuts a part of the inner modulation to lose the regular excitation. The exciting force is also reduced with the cutting thickness of the forward insert after a workpiece revolution. Because the theoretical position offset of the inserts in the feed direction is small, the side cutting edges of inserts are aligned in the same position. The process parameters are determined by estimating the removal volume of the backward insert with the phase shift. The range of the cutting speed and the height offset are given by the frequency of the chatter vibration, which is nearly the same as the natural frequency of the workpiece in single degree of freedom. The proposed cutting manner is validated using comparison between the single insert and double inserts cuttings.
Residual stress is one of the critical evaluation factors as well as machining accuracy and surface finish in cutting. From the perspective of the fastening strength of parts, residual stress in ...drilling has an influence on the product or part life. Especially in the aircraft manufacturing, the tensile residual stress is crucial as it can cause major accidents. However, few studies have focused on residual stress in drilling so far. Most of them investigated the characteristics of residual stress based on the experimental data. This paper discusses residual stress in drilling in terms of its mechanical effect. The residual stresses in the inner surfaces of holes were measured in the depth direction from the top of the plate. The change in the residual stress has good correlation with the chip flow direction and the load applied to the inner surface, which acts as a counter force to the cutting force near the outermost ends of the lips. The cutting force is determined using an analytical model based on the minimum cutting energy. The correlation between the residual stress and the direction of the load applied to the inner surface depends on the margin width and back taper on the peripheral sides of a drill. The effect of the margin contact on the residual stress is characterized by linear regression analysis. Finally, an analysis-neural network hybrid system was developed to estimate the residual stresses in drilling. In the system, the mechanical effects of the drilling process, which are the magnitude and direction of the load applied to the inner surface, are obtained through analytical simulation. Meanwhile, the margin effects are expressed as the coefficients in the linear functions, which are associated with the margin width and back taper angle by a neural network. Then, another neural network, working as a post process, estimates the residual stresses using the information of mechanical and margin effects. The developed system is validated by presenting a comparison between the estimated and the actual residual stresses.
Mitohormesis defines the increase in fitness induced by adaptive responses to mild mitochondrial stress. Here, we show that N‐acetyloxfenicine (NAO) exerted higher thermotolerance than an endogenous ...mitohormesis inducer, N‐acetyltyrosine (NAT). This activity was not observed in armyworm larvae injected with oxfenicine, suggesting the importance of N‐acetylation. NAO‐induced hormetic effect was triggered by transient perturbation of mitochondria, which causes a small increase in ROS production and leads to retrograde responses including enhanced expression of antioxidant enzyme genes via activation of FoxO transcription factors. Furthermore, pretreatment with NAO significantly repressed stress‐induced peroxidation of lipids in mice and growth of colorectal cancer HCT116 cells that had been transplanted into nude mice. Taken together, NAO is a potent mitohormesis inducer that is similar to NAT in terms of structure and functions.
N‐acetyloxfenicine (NAO) increases thermotolerance of insects. The NAO‐induced hormetic effect was triggered by transient perturbation of mitochondria, which causes a small increase in ROS production and leads to retrograde responses: NAO treatment enhanced the expression of antioxidant enzyme genes via activation of FoxO. Therefore, NAO is a potent mitohormesis inducer that shares close similarity with N‐acetyltyrosine in terms of structure and biological functions.
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