scholarly journals In-Process Tool Wear Detection Using Internal Encoder Signals for Unmanned Robust Machining

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Jari Repo ◽  
Anders Wretland ◽  
Tomas Beno ◽  
Jay Tu
Keyword(s):  
Wear Rate ◽  
Tool Wear ◽  
Frequency Band ◽  
Control Charts ◽  
Spectral Energy ◽  
Tool Wear Rate ◽  
Machining Processes ◽  
Statistical Process ◽  
Statistical Process Control Charts ◽  
Vibration Signatures

AbstractAutomated Tool Condition Monitoring (TCM) often relies on additional sensors sensitive to tool wear in order to achieve robust machining processes. The need of additional sensors could impede the implementation of tool monitoring systems in industry due to the cost and retrofitting difficulties. This paper has investigated the use of existing position encoder signals to monitor a special face turning process with constant feed per revolution and machining speed. A signal processing method by converting encoder signals into a complex-valued form and a new vibration signature extraction method based on phase function were developed to analyze the encoder signals in the frequency domain. The cumulative spectrum indicated that the spectral energy would shift from the lower to the higher frequency band with increasing cutting load. The embedded vibration signatures extracted from the encoder signals provided real-time detectability of the machining condition with distinguishable spectral modes. The embedded vibration signatures extracted from the encoder signals provided additional detectability of the machining condition with distinguishable spectral modes. In particular, tool chipping manifested itself as significant amplitude changes at a specific frequency band 20-30 Hz in the extracted vibration signatures. A new monitoring metric based on the XY-plane modulations combined with statistical process control charts was proposed. This metric was shown to be highly correlated to tool wear and tool wear rate. The results show that when tool chipping occurred, it could be detected when this tool wear rate value jumped in combination with breach of the control limits. This confirms that internal encoder signals, together with the proposed metric, could be an in-process toolwear monitor to help achieving unmanned robust machining.

Performance Analysis of Multi Wall Carbon Nanotubes (MWCNT) Coated Tool Electrode During Machining of Titanium Alloy (Ti6Al4V)

2020 ◽  
Author(s):  
Shailesh Shirguppikar ◽  
Maharudra Patil
Keyword(s):  
Surface Roughness ◽  
Wear Rate ◽  
Tool Wear ◽  
Tool Wear Rate ◽  
Machining Processes ◽  
Electric Discharge Machining ◽  
Multi Wall Carbon Nanotubes ◽  
Coated Electrode ◽  
Aluminum Electrodes ◽  
Titanium Alloy Ti6al4v

Abstract 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.

Patient Safety/Quality Improvement Primer, Part III: The Role of Simulation

2021 ◽  
pp. 019459982110133
Author(s):  
Ellen S. Deutsch ◽  
Sonya Malekzadeh ◽  
Cecelia E. Schmalbach
Keyword(s):  
Patient Safety ◽  
Quality Improvement ◽  
Control Charts ◽  
Neck Surgery ◽  
Resident Training ◽  
Statistical Process ◽  
Ensure Patient Safety ◽  
Statistical Process Control Charts ◽  
The Individual ◽  
The Impact

Simulation training has taken a prominent role in otolaryngology–head and neck surgery (OTO-HNS) as a means to ensure patient safety and quality improvement (PS/QI). While it is often equated to resident training, this tool has value in lifelong learning and extends beyond the individual otolaryngologists to include simulation-based learning for teams and health systems processes. Part III of this PS/QI primer provides an overview of simulation in medicine and specific applications within the field of OTO-HNS. The impact of simulation on PS/QI will be presented in an evidence-based fashion to include the use of run and statistical process control charts to assess the impact of simulation-guided initiatives. Last, steps in developing a simulation program focused on PS/QI will be outlined with future opportunities for OTO-HNS simulation.

CHARACTERIZATION OF ZrB2-SiC COMPOSITES WITH AN ANALYTICAL STUDY ON MATERIAL REMOVAL RATE AND TOOL WEAR RATE DURING ELECTRICAL DISCHARGE MACHINING

2016 ◽  
Vol 40 (3) ◽  
pp. 331-349 ◽  
Author(s):  
S. Sivasankar ◽  
R. Jeyapaul
Keyword(s):  
Wear Rate ◽  
Tool Wear ◽  
Relative Density ◽  
Material Removal Rate ◽  
Electrical Discharge ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Tool Wear Rate ◽  
Tool Materials

This research work concentrates on Electrical Discharge Machining (EDM) performance evaluation of ZrB2- SiC ceramic matrix composites with different tool materials at various machining parameters. Monolithic ZrB2 possesses lower relative density (98.72%) than composites. ZrB2 with 20 Vol.% of SiC possesses 99.74% of the relative density with improved hardness values. Bend strength and Young’s modulus increase with SiC addition until it reaches 20 Vol% and then decreasing. EDM performance on tool materials of tungsten, niobium, tantalum, graphite and titanium at various levels of pulse on time and pulse off time are analyzed. Graphite produces the best Material removal rate (MRR) for all the workpieces. Tool wear rate decreases with melting point and thermal conductivity of the tool material.

Experimental studies on graphite powder-mixed electro-discharge machining of Inconel 718 super alloys: Comparison with conventional electro-discharge machining

2018 ◽  
Vol 233 (2) ◽  
pp. 384-402 ◽  
Author(s):  
Santosh Kumar Sahu ◽  
Saurav Datta
Keyword(s):  
Thermal Conductivity ◽  
Residual Stress ◽  
Wear Rate ◽  
Tool Wear ◽  
Inconel 718 ◽  
Material Removal ◽  
Graphite Powder ◽  
Tool Wear Rate ◽  
Machined Surface ◽  
Electro Discharge Machining

Inconel 718 is a nickel-based super alloy widely applied in aerospace, automotive, and defense industries. Low thermal conductivity, extreme high temperature strength, strong work-hardening tendency make the alloy difficult-to-cut. In contrast to traditional machining, nonconventional route like electro-discharge machining is relatively more advantageous to machine this alloy. However, low thermal conductivity of Inconel 718 restricts electro-discharge machining from performing well. In order to improve the electro-discharge machining performance of Inconel 718, powder-mixed electro-discharge machining was reported in this paper. It was carried out by adding graphite powder to the dielectric media in consideration with varied peak discharge current. The morphology and topographical features of the machined surface including surface roughness, crack density, white layer thickness, metallurgical aspects (phase transformation, crystallite size, microstrain, and dislocation density), material migration, residual stress, microindentation hardness, etc. were studied and compared with that of the conventional electro-discharge machining. Additionally, effects of peak discharge current were discussed on influencing different performance measures of powder-mixed electro-discharge machining. Material removal efficiency and tool wear rate were also examined. Use of graphite powder-mixed electro-discharge machining was found to be better in performance for improved material removal rate, superior surface finish, reduced tool wear rate, and reduced intensity as well as severity of surface cracking. Lesser extent of carbon migration onto the machined surface as observed in powder-mixed electro-discharge machining in turn reduced the formation of hard carbide layers. As compared to the conventional electro-discharge machining, graphite powder-mixed electro-discharge machining exhibited relatively less microhardness and residual stress at the machined surface.

Reducing Unnecessary Respiratory Viral Testing to Promote High-Value Care

PEDIATRICS ◽  
2022 ◽  
Author(s):  
Olivia Ostrow ◽  
Deena Savlov ◽  
Susan E. Richardson ◽  
Jeremy N. Friedman
Keyword(s):  
Control Charts ◽  
Respiratory Infections ◽  
Audit And Feedback ◽  
Improvement Strategy ◽  
Statistical Process ◽  
Process Control Charts ◽  
Statistical Process Control Charts ◽  
Viral Testing ◽  
Return Visits ◽  
Viral Respiratory Infections

BACKGROUND AND OBJECTIVES: Viral respiratory infections are common in children, and practice guidelines do not recommend routine testing for typical viral illnesses. Despite results often not impacting care, nasopharyngeal swabs for viral testing are frequently performed and are an uncomfortable procedure. The aim of this initiative was to decrease unnecessary respiratory viral testing (RVT) in the emergency department (ED) and the pediatric medicine wards (PMWs) by 50% and 25%, respectively, over 36 months. METHODS: An expert panel reviewed published guidelines and appropriate evidence to formulate an RVT pathway using plan-do-study-act cycles. A multifaceted improvement strategy was developed that included implementing 2 newer, more effective tests when testing was deemed necessary; electronic order modifications with force functions; audit and feedback; and education. By using statistical process control charts, the outcomes analyzed were the percentage of RVT ordered in the ED and the rate of RVT ordered on the PMWs. Balancing measures included return visits leading to admission and inpatient viral nosocomial outbreaks. RESULTS: The RVT rate decreased from a mean of 3.0% to 0.5% of ED visits and from 44.3 to 30.1 per 1000 patient days on the PMWs and was sustained throughout the study. Even when accounting for the new rapid influenza test available in the ED, a 50% decrease in overall ED RVT was still achieved without any significant impact on return visits leading to admission or inpatient nosocomial infections. CONCLUSIONS: Through implementation of a standardized, electronically integrated RVT pathway, a decrease in unnecessary RVT was successfully achieved. Audit and feedback, reminders, and biannual education all supported long-term sustainability of this initiative.

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