Fracture and Wear as Factors Affecting Stochastic Tool-Life Models and Machining Economics

1977 ◽  
Vol 99 (1) ◽  
pp. 281-286 ◽  
Author(s):  
S. Rossetto ◽  
R. Levi
Keyword(s):  
Failure Modes ◽  
Probabilistic Approach ◽  
Cutting Tools ◽  
Distribution Functions ◽  
Profit Rate ◽  
Tool Failure ◽  
Factors Affecting ◽  
Machining Economics ◽  
Fracture Processes ◽  
Production Conditions

Under production conditions cutting tools often fail under several failure modes, the occurrence of a single one only for a given operation being rather exceptional. In light of this observation a stochastic model is developed, considering as causes of tool failure both wear and fracture processes. Machining economics are then analyzed with a probabilistic approach, deriving distribution functions of profit rate.

Effect of tool wear on chip formation during dry machining of Ti-6Al-4V alloy, part 2: Effect of tool failure modes

2015 ◽  
Vol 231 (9) ◽  
pp. 1575-1586 ◽  
Author(s):  
Shoujin Sun ◽  
Milan Brandt ◽  
Matthew S Dargusch
Keyword(s):  
Plastic Deformation ◽  
Tool Wear ◽  
Failure Modes ◽  
Flank Wear ◽  
Cutting Tools ◽  
Cutting Edge ◽  
Machined Surface ◽  
Tool Failure ◽  
Geometric Ratio ◽  
Cutting Speeds

Variation in the geometric and surface features of segmented chips with an increase in the volume of material removed and tool wear has been investigated at cutting speeds of 150 and 220 m/min at which the cutting tools fail due to gradual flank wear and plastic deformation of the cutting edge, respectively. Among the investigated geometric variables of the segmented chips, slipping angle, undeformed surface length, segment spacing, degree of segmentation and chip width showed the different variation trends with an increase in the volume of material removed or flank wear width, and achieved different values when tool failed at different cutting speeds. However, the chip geometric ratio showed a similar variation trend with an increase in the volume of material removed and flank wear width, and achieved the similar value at the end of tool lives at cutting speeds of both 150 and 220 m/min regardless of the different tool failure modes. Plastic deformation of the tool cutting edge results in severe damage on the machined surface of the chip and significant compression deformation on the undeformed surface of the chip.

Tool-Life Distributions—Part 1: Single-Injury Tool-Life Model

1977 ◽  
Vol 99 (3) ◽  
pp. 519-522 ◽  
Author(s):  
S. Ramalingam ◽  
J. D. Watson
Keyword(s):  
Tool Life ◽  
Manufacturing Systems ◽  
Rational Design ◽  
Probabilistic Models ◽  
Probabilistic Approach ◽  
Distribution Functions ◽  
Automated Manufacturing Systems ◽  
Tool Failure ◽  
Life Model ◽  
Life Distributions

The statistical variability of tool life in production machining must be accounted for in any rational design of large-volume or automated manufacturing systems. The probabilistic approach needed for such a design is presently limited by lack of data on tool-life distributions and by lack of knowledge of the underlying causes giving rise to tool-life scatter. Given these circumstances, on the basis of relevant physical arguments one may construct probabilistic models that produce distribution functions germane to the problem of tool-life scatter. This paper is concerned with such a study. This first part presents the results obtained on the assumption that the useful life of a tool is terminated by a single, catastrophic injury. Cases where resistance to tool failure is time-independent and time-dependent are examined. The case of tool failure caused by multiple injuries will be presented in Part 2.

Failure analysis of ceramic tool in intermittent turning of hardened steel

2017 ◽  
Vol 232 (12) ◽  
pp. 2140-2153 ◽  
Author(s):  
Xiuying Ni ◽  
Jun Zhao ◽  
Fuzeng Wang ◽  
Feng Gong ◽  
Xin Zhong ◽  
...  
Keyword(s):  
Cutting Forces ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Cutting Tools ◽  
Transient Temperature ◽  
Ceramic Tool ◽  
Tool Failure ◽  
Fracture Modes ◽  
Intermittent Turning ◽  
Cutting Speeds

The aim of this investigation is to identify the Al2O3-(W, Ti)C ceramic fracture modes and failure mechanisms under different cutting speeds and feed rates during intermittent turning of hardened 20CrMnTi steel. The failure surfaces of the cutting tools were examined by digital optical microscope and scanning electron microscope. The cutting forces and transient temperature in the intermittent turning process were measured during the entire life cycle. The experimental results showed that the cutting forces exhibited an increasing trend with the tool failure progression, which in turn accelerated the tool failure progression. The main failure modes of ceramic tools were wear and micro-chipping in the initial stage and final fractures, resulting from mechanical damage and thermal damage in intermittent turning processes. And the cutting temperature increased with the increase in cutting speed. The cutting speeds and feed rates were closely correlated with ceramic tool fracture modes and failure mechanisms. Furthermore, the combination of cutting parameters was divided into four regions with different fracture modes and failure mechanisms of cutting tools according to the fracture morphology of cutting tools. This partitioning analysis can provide a basis for the design and development of different ceramic cutting tools with the desired properties for different applications.

scholarly journals Factors affecting the appearance of the hump charge movement component in frog cut twitch fibers.

1991 ◽  
Vol 98 (2) ◽  
pp. 315-347 ◽  
Author(s):  
C S Hui
Keyword(s):  
Time Course ◽  
Extreme Case ◽  
Complete Recovery ◽  
Creatine Phosphate ◽  
Boltzmann Distribution ◽  
Distribution Functions ◽  
Charge Movement ◽  
Factors Affecting ◽  
Gap Technique ◽  
Voltage Dependent

Charge movement was measured in frog cut twitch fibers with the double Vaseline gap technique. Five manipulations listed below were applied to investigate their effects on the hump component (I gamma) in the ON segments of TEST minus CONTROL current traces. When external Cl-1 was replaced by MeSO3- to eliminate Cl current, I gamma peaked earlier due to a few millivolts shift of the voltage dependence of I gamma kinetics in the negative direction. The Q-V plots in the TEA.Cl and TEA.MeSO3 solutions were well fitted by a sum of two Boltzmann distribution functions. The more steeply voltage-dependent component (Q gamma) had a V approximately 6 mV more negative in the TEA.MeSO3 solution than in the TEA.Cl solution. These voltage shifts were partially reversible. When creatine phosphate in the end pool solution was removed, the I gamma hump disappeared slowly over the course of 20-30 min, partly due to a suppression of Q gamma. The hump reappeared when creatine phosphate was restored. When 0.2-1.0 mM Cd2+ was added to the center pool solution to block inward Ca current, the I gamma hump became less prominent due to a prolongation in the time course of I gamma but not to a suppression of Q gamma. When the holding potential was changed from -90 to -120 mV, the amplitude of I beta was increased, thereby obscuring the I gamma hump. Finally, when a cut fiber was stimulated repetitively, I gamma lost its hump appearance because its time course was prolonged. In an extreme case, a 5-min resting interval was insufficient for a complete recovery of the waveform. In general, a stimulation rate of once per minute had a negligible effect on the shape of I gamma. Of the five manipulations, MeSO3- has the least perturbation on the appearance of I gamma and is potentially a better substitute for Cl- than SO2-(4) in eliminating Cl current if the appearance of the I gamma hump is to be preserved.

scholarly journals A Comprehensive Review of the Mechanical Behavior of Suspension Bridge Tunnel-Type Anchorage

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Yafeng Han ◽  
Xinrong Liu ◽  
Ning Wei ◽  
Dongliang Li ◽  
Zhiyun Deng ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Failure Modes ◽  
Load Transfer ◽  
Mechanical Response ◽  
Soft Rock ◽  
Suspension Bridge ◽  
Development Trend ◽  
Factors Affecting ◽  
Research Results ◽  
Rock Strata

The recent surge of interest towards the mechanical response of rock mass produced by tunnel-type anchorage (TTA) has generated a handful of theories and an array of empirical explorations on the topic. However, none of these have attempted to arrange the existing achievements in a systematic way. The present work puts forward an integrative framework laid out over three levels of explanation and practical approach, mechanical behavior, and calculation method of the ultimate pullout force to compare and integrate the existing findings in a meaningful way. First, it reviews the application of TTA in China and analyzes its future development trend. Then, it summarizes the research results of TTA in terms of load transfer characteristics, deformation characteristics, failure modes, and calculation of ultimate uplift resistance. Finally, it introduces four field model tests in soft rock (mainly mudstone formations), and some research results are obtained. Furthermore, it compares the mechanical behavior of TTA in hard rock strata and soft rock strata, highlighting the main factors affecting the stability of TTA in soft rock formation. This paper proposes a series of focused topics for future investigation that would allow deconstruction of the drivers and constraints of the development of TTA.

scholarly journals Probabilistic Approach to Conditional Probability of Release of Hazardous Materials From Railroad Tank Cars During Accidents

2009 ◽  
Author(s):  
D. Y. Jeong
Keyword(s):  
Sensitivity Analysis ◽  
Conditional Probability ◽  
Impact Velocity ◽  
Probabilistic Sensitivity Analysis ◽  
Probabilistic Approach ◽  
Hazardous Materials ◽  
Relative Effect ◽  
Distribution Functions ◽  
Mean Values ◽  
Effective Collision

This paper describes a probabilistic approach to estimate the conditional probability of release of hazardous materials from railroad tank cars during train accidents. Monte Carlo methods are used in developing a probabilistic model to simulate head impacts. The model is based on the physics of impact in conjunction with assumptions regarding the probability distribution functions of the various factors that affect the loss of lading. These factors include impact velocity, indenter size, tank material, tank diameter, effective collision mass, and tank thickness. Moreover, each factor is treated as a random variable characterized by its assumed distribution function, mean value, and standard deviation (or variance). Reverse engineering is performed to back-calculate the mean values and standard deviations of these random variables that reproduce trends observed in available accident data. The calibrated model is then used to conduct a probabilistic sensitivity analysis to examine the relative effect of these factors on the conditional probability of release. Results from the probabilistic sensitivity analysis indicate that the most significant factors that affect conditional probability of release are impact velocity, effective collision mass, and indenter size.

Cutting Performance and Wear Mechanisms of an Al2O3-Based Micro-Nano-Composite Ceramic Tool

2010 ◽  
Vol 443 ◽  
pp. 244-249 ◽  
Author(s):  
Yong Hui Zhou ◽  
Jun Zhao ◽  
Xing Ai
Keyword(s):  
Failure Modes ◽  
Cutting Tools ◽  
Tool Material ◽  
Composite Ceramic ◽  
Cutting Performance ◽  
Nano Particles ◽  
Ceramic Tool ◽  
Nano Composite ◽  
Micro Particles ◽  
1045 Steel

An Al2O3-based composite ceramic cutting tool material reinforced with (W, Ti)C micro-particles and Al2O3 micro-nano-particles was fabricated by using hot-pressing technique, the composite was denoted as AWT. The cutting performance, failure modes and mechanisms of the AWT micro-nano-composite ceramic tool were investigated via continuous turning of hardened AISI 1045 steel in comparison with those of an Al2O3/(W, Ti)C micro-composite ceramic tool SG-4 and a cemented carbide tool YS8. Worn and fractured surfaces of the cutting tools were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results of continuous turning revealed that tool lifetime of the AWT ceramic tool was higher than that of the SG-4 and YS8 tools at all the tested cutting speeds. The longer tool life of the AWT composite ceramic tool was attributed to its synergistic strengthening/toughening mechanisms induced by the (W, Ti)C micro-particles and Al2O3 nano-particles.

A New Probabilistic Approach for Accurate Fatigue Data Analysis of Ceramic Materials

1999 ◽  
Author(s):  
Bjoern Schenk ◽  
Peggy J. Brehm ◽  
M. N. Menon ◽  
William T. Tucker ◽  
Alonso D. Peralta
Keyword(s):  
Data Analysis ◽  
Failure Modes ◽  
Probabilistic Approach ◽  
Time Dependent ◽  
Material Strength ◽  
Static Fatigue ◽  
Oak Ridge ◽  
Fatigue Data ◽  
Ceramic Components ◽  
Dependent Failure

Statistical methods for the design of ceramic components for time-dependent failure modes have been developed which can significantly enhance component reliability, reduce baseline data generation costs, and lead to more accurate estimates of slow crack growth (SCG) parameters. These methods are incorporated into the AlliedSignal Engines CERAMIC and ERICA computer codes. Use of the codes facilitates generation of material strength parameters and SCG parameters simultaneously, by pooling fast fracture data from specimens that are of different sizes, or stressed by different loading conditions, with data derived from static fatigue experiments. The codes also include approaches to calculation of confidence bounds for the Weibull and SCG parameters of censored data and for the predicted reliability of ceramic components. This paper presents a summary of this new fatigue data analysis technique and an example demonstrating the capabilities of the codes with respect to time-dependent failure modes. This work was sponsored by the U.S. Department of Energy Oak Ridge National Laboratory (DoE/ORNL) under Contract No. DE-AC05-84OR21400.

Diamond Coatings for Machining: Coating Thickness Effects

2009 ◽  
Author(s):  
Feng Qin ◽  
Y. Kevin Chou ◽  
Dustin Nolen ◽  
Raymond G. Thompson
Keyword(s):  
Residual Stresses ◽  
Coating Thickness ◽  
Cutting Forces ◽  
Failure Modes ◽  
Cutting Tools ◽  
Cutting Edge ◽  
The Other ◽  
Diamond Coatings ◽  
Coated Tools ◽  
Other Hand

Chemical vapor deposition (CVD)-grown diamond films have found applications as a hard coating for cutting tools. Even though the use of conventional diamond coatings seems to be accepted in the cutting tool industry, selections of proper coating thickness for different machining operations have not been often studied. Coating thickness affects the characteristics of diamond coated cutting tools in different perspectives that may mutually impact the tool performance in machining in a complex way. In this study, coating thickness effects on the deposition residual stresses, particularly around a cutting edge, and on coating failure modes were numerically investigated. On the other hand, coating thickness effects on tool surface smoothness and cutting edge radii were experimentally investigated. In addition, machining Al matrix composites using diamond coated tools with varied coating thicknesses was conducted to evaluate the effects on cutting forces, part surface finish and tool wear. The results are summarized as follows. (1) Increasing coating thickness will increase the residual stresses at the coating-substrate interface. (2) On the other hand, increasing coating thickness will generally increase the resistance of coating cracking and delamination. (3) Thicker coatings will result in larger edge radii; however, the extent of the effect on cutting forces also depends upon the machining condition. (4) For the thickness range tested, the life of diamond coated tools increases with the coating thickness because of delay of delaminations.

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