928,142 research outputs found
A performance of 2 dimensional ultrasonic vibration assisted milling in cutting force reduction, on aluminium AL6061
This paper were investigate a performance of 2 Dimensional Ultrasonic Vibration assisted Milling (UVAM) toward Aluminium Al 6061. The focus is to find the performance of reduction of cutting force compared to the conventional machining in the industries shop floor. Due to the major effect of cutting force of production in industries, the excessive cutting force problem must be investigated deeply as it will cause shortens tool life and reduces the production rate. A scientific approach has been found in order to reduce the cutting force during machining which is integrating the ultrasonic concept into workpiece. The modelling of vibration cutting ratio has been simulated to find the time force contact and non-contact. Thus, less cutting force could be found. The ultrasonic vibration platform that generated by XY25XS from Cedrat Technologies is travelled in X direction as a feed movement. Thus, the X and Y axis vibration actuate along the workpiece for the machining process. The performance of UVAM in cutting force reduction found the superior benefits of UVAM is come from the alternating cycle’s between tool and workpiece. The comparison between UVAM and conventional machining in reduction of cutting force is 32%. The potential of the UVAM tool wear and tool life will be discussed deeply in finding and next in the conclusion section
Cold machining of high density tungsten and other materials
Cold machining process, which uses a sub-zero refrigerated cutting fluid, is used for machining refractory or reactive metals and alloys. Special carbide tools for turning and drilling these alloys further improve the cutting performance
Tool Life of PM-HSS Cutting Tools when Milling of Titanium Alloy
Machining of titanium alloys meets with poor life of a cutting tool. It is caused by a low thermal conductivity and by a high strength-to-weight ratio of the alloys. Various approaches for cost-effective and productive machining titanium alloys are still researched. One of methods can be using the cutters made of modern high-speed steel (HSS) as a product of a powder metallurgy (PM) process. These materials (PM-HSS) possess better and homogenous mechanical properties than conventional high-speed steel. The PM-HSS cutters equipped with any effective coating allow increase cutting speed
to the level which is typical for uncoated cemented carbide, while price of the tool is lower. In the article several PM-HSS cutting tool materials were compared to conventional cobalt based HSS from the tool life point of view. It was proved that conventional high-speed steel offers very long tool life and high tool performance at speed of 30 m/min. However the regular tooth pitch significantly decreases tool life for this cutting tool material. The main benefit of PM-HSS cutters can be fully utilized when cutting speed about 50 m/min is applied. The cutters coated by effective thermal barrier showed longer tool life and higher performance of the cutting tools
Investigation of tool geometry effect and penetration strategies on cutting forces during thread milling
The application of thread milling is increasing in industry because of its inherent advantages over other thread cutting techniques. The objective of this study is to investigate the effect of milling cutter tool geometry on cutting forces during thread milling. The proposed method can compare the performance of milling cutters in spite of the different number of tooth. The best thread milling cutter among the studied tools was determined from the cutting forces point of view. Furthermore, this study also pinpoints the best penetration strategy that provides minimum cutting forces. Lower cutting force variations will lead to fewer vibrations of the tool which in turn will produce accurate part.Postdoc de V Sharma financé par la région Bourgogn
The role of tool geometry in process damped milling
The complex interaction between machining structural systems and the cutting process results in machining instability, so called chatter. In some milling scenarios, process damping is a useful phenomenon that can be exploited to mitigate chatter and hence improve productivity. In the present study, experiments are performed to evaluate the performance of process damped milling considering different tool geometries (edge radius, rake and relief angles and variable helix/pitch). The results clearly indicate that variable helix/pitch angles most significantly increase process damping performance. Additionally, increased cutting edge radius moderately improves process damping performance, while rake and relief angles have a smaller and closely coupled effect
The performance of modified jatropha-based nanofluid during turning process
The industry's extensive use of petroleum-based metalworking fluid (MWF) harms the environment
and humans. The production of bio-based MWF, especially from crude jatropha oil (CJO), has therefore taken
numerous initiatives. This aimed to formulate newly modified jatropha oil (MJO) with the addition of 0.05wt.%
hBN and 0.05wt.% MoS2 as the nanofluid for MWF. The performance of the nanofluids was determined
through the turning process in terms of cutting temperature, workpiece surface roughness, tool life and tool
wear of the tool lubricated by the nanofluids. The performance of the nanofluid samples was compared with
the synthetic ester (SE). From the results, after conducted 100mm axial cutting length MJO+hBN+MoS2
recorded the lowest in cutting temperature and surface roughness compared to all samples. The result shows
that MJO+hBN+MoS2 has longer tool life (6500mm) compared to SE (6000mm). Abrasion and adhesion were
observed as the dominant tool wear mechanism. In conclusion, MJO+hBN+MoS2 shows better machining
performance and has the potential to be an environmentally friendly metalworking fluid
Machining performance of vegetable oil with phosphonium- and ammonium-based ionic liquids via MQL technique
Thermo-mechanical loads are the main factor that influences the tool wear and product surfaces during machining processes. Lubrication in metal cutting is an effective medium to reduce frictional forces and wear on the tool-workpiece interfaces. On this regards, the advantages of using refined bio-based metalworking fluids (MWFs) with the presence of low toxic, biocompatible and oil-miscible ionic liquids (ILs) additives ([N1,8,8,8][NTf2] (AIL) & [P6,6,6,14][(iC8)2PO2] (PIL)) at nominal weight concentrations of 1, 5 and 10% are explored during orthogonal cutting of AISI 1045 steel. Accordingly, the lubricants are supplied via minimum quantity lubrication (MQL) technique and comparative studies are conducted against the performance of the neat modified Jatropha-based lubricant (MJO) and commercially available synthetic ester-based MQL cutting fluid (SE). The combination of mist supply of the MJOs during machining have a great impact on cleaner production that eliminates the excessive usage of fluids and supports the utilization of environmentally friendly chemicals. This work extends the application of a minute quantity of fully miscible ILs in polar vegetable-based MWF which proven to provide a significant improvement on the lubrication effect of the MJO. MJOþAIL10% and MJOþPIL1% showed the best cutting performance amongst all lubricant mixtures with reduction of cutting forces and specific cutting energy by 4 to 5%, cutting temperatures by 7 to 10%, friction coefficient by 2 to 3%, tool-chip contact length by 8 to 11%, chip thickness by 22 to 25%, friction angle by 1 to 2% and increased shear angle by 25 to 29% compared to the SE. Besides, the effect of low friction and reduced cutting forces produced lower specific cutting energy that promotes “greener” and more sustainable working environment
Design of a smart turning tool with application to in-process cutting force measurement in ultraprecision and micro cutting
In modern micromachining, there is a need to measure and monitor certain machining process parameters in process so as to detect tool wear in real time, to optimize the process parameters setup, and to render the machining process some level of smartness and intelligence. This paper presents the innovative design of a smart turning tool using two pieces of piezoelectric films to measure cutting and feed force in real time. The tool was tested on its performance through the calibration and cutting trials against the commercial dynamometer. The results show the smart turning tool has achieved the performance as designed
High-Power Fiber Laser Cutting for 50-mm-Thick Cement-Based Materials
This experimental research highlights the applicability of laser cutting to cement-based materials using multimode fiber lasers. A 9 kW multimode fiber laser is used, and the experimental variables are the water-to-cement ratio, laser speed, and material compositions such as cement paste, cement mortar and ultra high performance concrete (UHPC). The laser cutting performance on the cement-based materials is investigated in the downward laser direction. The kerf width and penetration depth of the cement-based materials are quantitatively evaluated with the parameters in the surface and cross section of the specimens after the laser cutting. Moreover, the material removal zone of each specimen is compared in terms of the penetration shapes in the cross-sectional view. Based on experimental observations, the interaction mechanism between the laser and cement-based materials is proposed
A task and performance analysis of endoscopic submucosal dissection (ESD) surgery
BACKGROUND:
ESD is an endoscopic technique for en bloc resection of gastrointestinal lesions. ESD is a widely-used in Japan and throughout Asia, but not as prevalent in Europe or the US. The procedure is technically challenging and has higher adverse events (bleeding, perforation) compared to endoscopic mucosal resection. Inadequate training platforms and lack of established training curricula have restricted its wide acceptance in the US. Thus, we aim to develop a Virtual Endoluminal Surgery Simulator (VESS) for objective ESD training and assessment. In this work, we performed task and performance analysis of ESD surgeries.
METHODS:
We performed a detailed colorectal ESD task analysis and identified the critical ESD steps for lesion identification, marking, injection, circumferential cutting, dissection, intraprocedural complication management, and post-procedure examination. We constructed a hierarchical task tree that elaborates the order of tasks in these steps. Furthermore, we developed quantitative ESD performance metrics. We measured task times and scores of 16 ESD surgeries performed by four different endoscopic surgeons.
RESULTS:
The average time of the marking, injection, and circumferential cutting phases are 203.4 (σ: 205.46), 83.5 (σ: 49.92), 908.4 s. (σ: 584.53), respectively. Cutting the submucosal layer takes most of the time of overall ESD procedure time with an average of 1394.7 s (σ: 908.43). We also performed correlation analysis (Pearson's test) among the performance scores of the tasks. There is a moderate positive correlation (R = 0.528, p = 0.0355) between marking scores and total scores, a strong positive correlation (R = 0.7879, p = 0.0003) between circumferential cutting and submucosal dissection and total scores. Similarly, we noted a strong positive correlation (R = 0.7095, p = 0.0021) between circumferential cutting and submucosal dissection and marking scores.
CONCLUSIONS:
We elaborated ESD tasks and developed quantitative performance metrics used in analysis of actual surgery performance. These ESD metrics will be used in future validation studies of our VESS simulator
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