Modeling of flatness errors in end milling of thin-walled components

2020 ◽  
pp. 095440542094921
Author(s):  
Ankit Agarwal ◽  
Kaushal A Desai
Keyword(s):  
End Milling ◽  
Force Model ◽  
Related Factors ◽  
Element Analysis ◽  
Computational Tools ◽  
Geometric Dimensioning And Tolerancing ◽  
Thin Walled ◽  
The Individual ◽  
Machining Strategies ◽  
Flatness Error

Machined components deviate in size, form, and orientation in comparison to actual features realized by the designer. The deviations originate from several process-related factors and can be specified as per the Geometric Dimensioning and Tolerancing standards (ASME Y14.5-2009 or ISO 1101:2017). According to these standards, the deviation of planar or flat components is expressed in the form of flatness error. This article presents an overall framework to estimate static deflection–induced flatness errors during end milling of thin-walled planar components. The framework incorporates the Mechanistic force model, finite element analysis–based workpiece deflection model, and particle swarm optimization–based algorithm to estimate flatness-related parameters. The individual elements of the proposed framework are implemented in the form of computational tools, and a set of experiments are conducted on thin-walled parts. It has been observed that the static deflections of the thin-walled component have considerable influence on flatness error, and the same can be captured effectively using the proposed framework. The study also investigates the effect of inevitable aspects of the thin-walled machining, such as workpiece rigidity and thinning on the flatness error. The findings of the present study aid process planners in devising appropriate machining strategies to manufacture thin-walled components within tolerances specified by the designer.

Rigidity Regulation Approach for Geometric Tolerance Optimization in End Milling of Thin-walled Components

2021 ◽  
pp. 1-34
Author(s):  
Ankit Agarwal ◽  
K A Desai
Keyword(s):  
End Milling ◽  
Traditional Approach ◽  
Force Model ◽  
Geometric Tolerances ◽  
Novel Approach ◽  
Cutting Sequences ◽  
Finish Cutting ◽  
Thin Walled ◽  
Cutting Sequence ◽  
Regulation Approach

Abstract The paper presents a novel approach to improve geometric tolerances (flatness and cylindricity) by manipulating the rigidity among finishing and roughing cutting sequences during end milling of thin-walled components. The proposed approach considers the design configuration of the thin-walled component as an input and aims to determine semi-finished geometry such that the geometric tolerances are optimized while performing finish cutting sequence. The objective is accomplished by combining Mechanistic force model, Finite Element (FE) analysis based workpiece deflection model and Particle Swarm Optimization (PSO) technique to determine optimal disposition of material along the length of component thereby regulating rigidity. The algorithm has been validated by determining rigidity regulated semi-finished geometries for thin-walled components having straight, concave and convex configurations. The outcomes of the proposed algorithm are substantiated further by conducting a set of end milling experiments for each of these cases. The results of the proposed strategy are compared with a traditional approach considering no change in the rigidity of component along length of the cut. It is demonstrated that the proposed approach can effectively optimize geometric tolerances for thin-walled components during end milling operation.

The Deformation Analysis for Flank Milling of Thin-Walled Rectangle Plate Based on Flexible Force Model

2011 ◽  
Vol 189-193 ◽  
pp. 1555-1561
Author(s):  
Liang Hong Xiao ◽  
Liang Tang ◽  
Zi Hua Hu ◽  
Zheng Kuang ◽  
Ju Long Yuan
Keyword(s):  
End Milling ◽  
Simulation Method ◽  
Flank Milling ◽  
Deformation Analysis ◽  
Force Model ◽  
Machining Quality ◽  
Finite Element Numerical Simulation ◽  
Thin Walled ◽  
Experimental Values

By considering the effects of flank milling deformation on machining quality of thin-walled rectangle plate, the flexible force model of spiral end milling is built on the condition that the influence of part/tool on milling is considered with FE (finite element) numerical simulation method in this paper. Based on the flexible force model, the distribution curve of machining deformation is got by the FE prediction for the flank milling of the thin-walled rectangle plate, and the compensation strategy of CL (cutting location) is established. Some contrast tests between the flexible force model, the deflection simulation and error compensation values to the rigid force model and experimental values of flank milling are performed, respectively. The results indicate that both the flexible force model founded in the paper and the analyzed values of flank milling deflection of thin-walled rectangle plate are reliable, and an effective judgment is provided to advance the machining quality of thin-walled parts.

Root Cause Analyses of Suicides of Mental Health Clients

Crisis ◽  
2015 ◽  
Vol 36 (5) ◽  
pp. 316-324 ◽  
Author(s):  
Donna Gillies ◽  
David Chicop ◽  
Paul O'Halloran
Keyword(s):  
Mental Health ◽  
Suicide Prevention ◽  
Common Factor ◽  
Data Collection Tool ◽  
Related Factors ◽  
Root Cause ◽  
Communication Problems ◽  
The Individual ◽  
Mental Health Clients ◽  
Imminent Risk

Abstract. Background: The ability to predict imminent risk of suicide is limited, particularly among mental health clients. Root cause analysis (RCA) can be used by health services to identify service-wide approaches to suicide prevention. Aims: To (a) develop a standardized taxonomy for RCAs; (b) to quantitate service-related factors associated with suicides; and (c) to identify service-related suicide prevention strategies. Method: The RCAs of all people who died by suicide within 1 week of contact with the mental health service over 5 years were thematically analyzed using a data collection tool. Results: Data were derived from RCAs of all 64 people who died by suicide between 2008 and 2012. Major themes were categorized as individual, situational, and care-related factors. The most common factor was that clients had recently denied suicidality. Reliance on carers, recent changes in medication, communication problems, and problems in follow-through were also commonly identified. Conclusion: Given the difficulty in predicting suicide in people whose expressions of suicidal ideation change so rapidly, services may consider the use of strategies aimed at improving the individual, stressor, support, and care factors identified in this study.

Safety climate and related factors in rehabilitation nurses of hospitals in Iran

Work ◽  
2021 ◽  
pp. 1-8
Author(s):  
Javad vatani ◽  
Zahra Khanikosarkhizi ◽  
Mohammad Ali Shahabi Rabori ◽  
mohammad khandan ◽  
Mohsen aminizadeh ◽  
...  
Keyword(s):  
Safety Climate ◽  
Cross Sectional Study ◽  
P Value ◽  
Related Factors ◽  
Cross Sectional ◽  
Climate Assessment ◽  
Safety Work ◽  
Significant Difference ◽  
Training Courses ◽  
The Individual

BACKGROUND: Safety climate is a common insight of staff that indicates individuals’ attitudes toward safety and priority of safety at work. OBJECTIVES: Nursing is a risky job where paying attention to safety is crucial. The assessment of the safety climate is one of the methods to measure the safety conditions in this occupation. The aim of this study was to assess the safety climate of rehabilitation nurses working in hospitals in Tehran. METHODS: This is a cross-sectional study which was carried out on 140 rehabilitation nurses selected from all hospitals and clinics in Tehran in 2019. To collect the required data, a two-section questionnaire was used. The first section was related to demographic factors and the second part (22 statements) was to measure the safety climate using nurses’ safety climate assessment questionnaire. The collected data were analyzed by SPSS V16 using independent t-test, ANOVA, Kruskal-Wallis and Mann-Whitney U test at the 5% level. RESULTS: Findings showed that the total mean of safety climate was 3.06±0.56. According to the results, a significant difference was found between the positive and negative satisfaction of nurses with safety climates (P-value = 0.03), communication with nurses (P-value = 0.01) and supervisors’ attitude (P-value = 0.02). Furthermore, a significant difference in safety climate between the individual with the second job and the individual without second could be observed (P-value = 0.01). CONCLUSIONS: The results indicated that the safety climate was not at an acceptable level. Thus, it is essential to introduce safety training courses (e.g. safety, work-rest balance, and so on) and to improve the safety performance at work.

scholarly journals Reinforcing Effect of Carbon Nanotubes/Surfactant Dispersions in Portland Cement Pastes

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Oscar A. Mendoza Reales ◽  
Caterin Ocampo ◽  
Yhan Paul Arias Jaramillo ◽  
Juan Carlos Ochoa Botero ◽  
Jorge Hernán Quintero ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Cement Matrix ◽  
Multiwalled Carbon ◽  
Element Analysis ◽  
Cement Pastes ◽  
Reinforcing Effect ◽  
Linear Elastic ◽  
Crack Propagation Process ◽  
Negative Effect ◽  
The Individual

Decoupling the individual effects of multiwalled carbon nanotubes (MWCNTs) and surfactants when used as reinforcement materials in cement-based composites is aimed in this study. Powder MWCNTs were dispersed in deionized water using different types of surfactants as chemical dispersing agents and an ultrasonic tip processor. Cement pastes with carbon nanotubes additions of 0.15% by mass of cement were produced in two steps: first, the MWCNT/surfactant dispersions were combined with the mixing water, and then, cement was added and mixed until a homogeneous paste was obtained. Mechanical properties of the pastes cured at 7 days were measured, and their fracture behavior was characterized using the linear elastic finite element analysis. It was found that the reinforcing effect of MWCNT was masked by the negative effect of surfactants in the cement matrix; nevertheless, nanotubes were capable of increasing both stress and strain capacity of the composite by controlling the crack propagation process at the tip of the crack.

Development of Analytical Force Model for End Milling of Magnesium Matrix Composites

2020 ◽  
Author(s):  
Nishita Anandan ◽  
M. Ramulu
Keyword(s):  
End Milling ◽  
Coefficient Of Thermal Expansion ◽  
Cutting Edge ◽  
Force Model ◽  
Matrix Composites ◽  
Magnesium Metal ◽  
Magnesium Matrix Composites ◽  
The Matrix ◽  
Thrust Forces ◽  
Good Agreement

Abstract An analytical approach to predict the cutting forces in end milling of magnesium metal matrix composite is presented in this study. The model was developed by identifying three events that occur when the cutting edge encounters the composite, when an element of the cutting edge encounters just the particles, it may fracture the particle, when the element encounters pure ductile matrix, plastic deformation occurs and when the element is in contact with both the particle and matrix, particle debonding occurs due to mismatch in coefficient of thermal expansion. The probability of these events was estimated using the particle concentration and the distribution in the matrix. A cutting force model is developed by considering the stresses and forces experienced by the cutting edge contributed by these events. The predicted feed forces and the measured forces are in good agreement for most of the cutting conditions. While, the predictive thrust forces were found to diverge at higher feed of 1 mm/rev.

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