Edge Wear Research Articles

Drill Wear Feature Identification under Varying Cutting Conditions Using Vibration and Cutting Force Signals and Data Mining Techniques

Monitoring drill wear is a major topic in automated manufacturing operations. This paper presents an effective drill wear feature identification scheme based on robust clustering techniques. Three types of drill wear (namely; chisel wear, chipped edge and flank wear) are artificially induced on the drill point. The drill cutting edge wear related features are extracted experimentally by processing the force signals from a three-axis piezoelectric load cell in both the time and frequency domains. Techniques based on the short time Fourier transform (STFT), wavelet transform (WT) and statistical parameters are utilized for feature extraction. The sensitivity of the proposed method is tested under different cutting feed and speed conditions. The computational study is conducted using the features extracted from three dimensional vibration and cutting force signals. The type of drill wear and related variations in the cutting forces are identified using robust clustering methods. The objective is to isolate regions in the feature space, each region corresponding to one of the drill wear types. Results show that power spectral density data clusters better than data obtained using wavelet coefficients. The clustering results can be used to design classifiers for real time monitoring of wear conditions while drilling.

Effects of deep cryogenic treatment on the wear development of H13A tungsten carbide inserts when machining AISI 1045 steel

In this study, the effects of deep cryogenic treatment (93 K) on the surface and sub-surface wear development of H13A cobalt-bonded tungsten carbide cutting inserts during the wet machining of AISI 1045 steel were investigated. Cutting inserts were subjected to short periods (171–553 s) of turning at cutting speeds of 50–140 m/min, during which time mass measurements were taken and the worn edges were imaged and scanned, by optical microscopy and light interferometry, at regular intervals. Sections were taken following machining so that sub-surface features could be observed by scanning electron microscopy. It was determined that cryogenic treatment resulted in a 9.2 % increase in hardness and an increase in abrasive wear resistance, although microstructural changes and sub-surface behaviours suggested a corresponding decrease in toughness may have occurred.

Risk of Impingement and Third-body Abrasion With 28-mm Metal-on-metal Bearings

Concerns have been raised about the sequelae of metal-on-metal (MoM) bearings in total hip arthroplasty (THA). However, retrieval studies, which offer the best insight into the clinically relevant mechanisms of MoM wear, have followed predictable trends to date such as indicting cobalt-chromium (CoCr) metallurgy, cup design, high conformity between the head and cup, "steep cups," "microseparation," and "edge wear." We wished to evaluate a set of retrieved 28-mm MoM THA for signs of (1) cup-to-stem impingement; (2) normal wear pattern and concomitant stripe damage on femoral heads that would signify adverse wear mechanics; and (3) well-defined evidence of third-body scratches on bearings that would indicate large abrasive particles had circulated the joint space. Ten 28-mm MOM retrievals were selected on the basis that femoral stems were included. Revision surgeries at 3 to 8 years were for pain, osteolysis, and cup loosening. CoCr stems and the MoM bearings were produced by one vendor and Ti6Al4V stems by a second vendor. All but two cases had been fixed with bone cement. We looked for patterns of normal wear and impingement signs on femoral necks and cup rims. We looked for adverse wear defined as stripe damage that was visually apparent on each bearing. Wear patterns were examined microscopically to determine the nature of abrasions and signs of metal transfer. Graphical models recreated femoral neck and cup designs to precisely correlate impingement sites on femoral necks to cup positions and head stripe patterns. The evidence revealed that all CoCr cup liners had impinged on either anterior or posterior facets of femoral necks. Liner impingement at the most proximal neck notch occurred with the head well located and impingement at the distal notch occurred with the head rotated 5 mm out of the cup. The hip gained 20° motion by such a subluxation maneuver with this THA design. All heads had stripe wear, the basal and polar stripes coinciding with cup impingement sites. Analysis of stripe damage revealed 40 to 100-μm wide scratches created by large particles ploughing across bearing surfaces. The association of stripe wear with evidence of neck notching implicated impingement as the root cause, the outcome being the aggressive third-body wear. We found consistent evidence of impingement, abnormal stripe damage, and evidence of third-body abrasive wear in a small sample of one type of 28-mm MoM design. Impingement models demonstrated that 28-mm heads could lever 20° out of the liners. Although other studies continue to show good success with 28-mm MoM bearings, their use has been discontinued at La Pitie Hospital.

Testing a taphonomic predictive model of edge damage formation with Middle Stone Age points from Pinnacle Point Cave 13B and Die Kelders Cave 1, South Africa

The interpretation of taphonomic and behavioral lithic edge wear formation is complicated by equifinality of edge damage morphologies. Rejecting hypotheses that edge damage originates from taphonomic processes is standard practice for many archaeological analyses and should be incorporated into lithic use-wear more explicitly. Quantitative hypothesis testing is advocated here, and facilitated by recording edge wear observations in an image referenced GIS spatial environment. A taphonomic predictive model was generated using trampling and flint-knapping experiments. Trampling experiments were conducted to determine how edge damage is distributed along tool edges due to non-use related, taphonomic processes. Experiments designed to test the assumption that undisturbed flakes do not preferentially orient either surface side-up (dorsal or ventral) were performed. Furthermore, it is argued that artifact orientation data, if available, can also be used to assess whether the frequency of edge damage is correlated with the degree of disturbance. This taphonomic predictive model is then statistically compared with frequency and distribution edge damage data from two South African Middle Stone Age sites. The research presented here illustrates the usefulness of edge damage distribution analysis for accounting for taphonomic processes as causal agents of edge damage formation, and strengthening behavioral interpretations regarding tool function. Bringing tool wear observations into a uniform spatial structure is one avenue for standardization of lithic use-wear analysis.

Industrial Sawing of Pinus sylvestris L.: Power Consumption

The wood industry continues to strive to reduce production costs and increase productivity to remain competitive. Knowledge of the effect of wood cutting parameters on power consumption could increase energy efficiency, reducing operating costs and increasing profitability. Measuring power consumption also provides information about other variables, such as tool edge wear, occurrence of catastrophic failures, and other parameters that affect the quality of the sawn boards and the momentary efficiency of the breakdown process. In this work, power consumption during sawing of Pinus sylvestris L. using a double arbor circular saw was investigated. Both climb-sawing and counter-sawing were considered. The experiments were carried out under normal production circumstances in two Swedish sawmills. The relationship between cutting parameters and theoretical power consumption was investigated. The experimental power consumption increased by 11 to 35% during an 8-h shift, mainly due to an increase in the tooth radius. Additionally, this study showed that climb-sawing consumed more power than counter-sawing.

Predicting wear and blood metal ion levels in metal‐on‐metal hip resurfacing

Suboptimal component position and design are thought to lead to edge wear and raised blood metal ion levels in metal-on-metal hip resurfacing (MOM-HR). These factors are thought to influence the "contact patch to rim distance" (CPRD), and calculation of this distance may improve prediction of wear and blood metal ion levels. We measured blood cobalt and chromium ion levels and the wear rates of the bearing surfaces in 165 MOM-HR retrieval cases. We then determined the contribution and effect sizes of cup inclination and version angles, component size and design, and CPRD (calculated from case-specific data) on blood metal ion levels and component wear rates. Acetabular orientation explained between 16.3% and 28.5% of the variation in wear rates and metal ion levels, whereas component size and design explained between 7.3% and 21.8% of the variability. In comparison, CPRD explained up to 67.7% of the variability, significantly greater than any other variable (all p < 0.0001). CPRD is a good predictor of wear and improves our understanding of wear performance and the mechanisms leading to edge loading.

Research of Wear Mechanisms of PCD Cutting Tools in Sand Mold Milling

The PCD cutting tool is used to dry mill foundry sand materials, SEM is used for observing the wear morphology of the cutting tool, and EDS is used to analyze the components of the wear area of the cutting tool so that the wear morphology of the cutting tool and the wear mechanisms are studied. The research results indicate that the wear morphology of the PCD cutting tool in cutting sand molds are rake face wear, cutting edge wear, and flank wear. The wear mechanism of the PCD cutting tool is abrasive wear, which is caused when PCD crystal particles produced in the mechanical friction between the cutting tool and the work-piece material in cutting continuously come off. Mechanical fatigue wear is the main cause of mechanical fatigue caused by alternating load which is generated by the interrupted cutting and high-frequency mechanical shock of workpiece material hard point.

Determination of the Real Cutting Edge Wear Contact Area on the Tool-Workpiece Interface in the Light of Cutting Forces Variations

The determination of actual stresses over the tool-workpiece interface has long been a matter of debate among researchers. Evaluation of the nature and the geometry of the wear contact area were always associated with many, sometime impractical, assumptions. The indeterministic fashion of edge wear and deformation requires a more realistic way to predict the actual wear contact area. In the current study, many wear area patterns are proposed considering the different wear modes of the cutting edge. The selection of the most correlated pattern to a specific edge deformation is justified using the relevant variations in the radial and the axial force components. For a regular wear over the entire cutting edge, a wear pattern that considers nose and/or flank is justified. When the cutting edge plastically fails, a pattern that considers only nose wear is preferred. As the cutting edge is subjected to many types of irregular disturbances of edge fracture and chipping, a wear pattern considering both flank and nose wear is selected.

On-line tool wear measurement for ball-end milling cutter based on machine vision

Cutting tool wear is known to affect tool life, surface quality and production time. In this paper, a new on-line tool wear measuring algorithm is proposed to acquire tool wear using machine vision in order to establish on-line tool wear monitoring model for assessing degree of wear and remaining useful tool life. The algorithm first adopts machine vision to acquire tool wear images from CCD camera on-line for ball-end cutter. Tool tip points are determined and wear detection areas are optimized within captured tool wear images. Tool wear images before machining and in machining process are captured to compare the corresponding image column for judging whether this image column has emerged wear. Then the initial detection of wear edge points with pixel accuracy is given to scan pixel columns within the constructed wear detection areas in vertical direction. The exact detection algorithm of wear edge points with sub-pixel accuracy is proposed to increase the precision of detected wear edge points. The tool wear can be computed based on the detected wear edge points. Experimental work and validation of the established on-line tool wear measurement method are performed in a five-axis milling center by using stainless steel 1Cr18Ni9Ti and ball-end cutter of cemented carbide. The obtained measurement results by using the proposed method are compared with those gotten by measuring directly with microscope. The proposed method is shown to be reliable and effective for on-line tool wear measurement.

A comparative study of high-speed machining of Ti–6Al–4V and Inconel 718 - part I: effect of dynamic tool edge wear on cutting forces

Part II of the present study is a comparative study of high-speed machining of Ti-6Al-4V and Inconel 718, focusing on a comparison between the effects of dynamic tool edge wear on cutting vibrations. This paper describes in detail how cutting vibrations were measured and how vibration signals were processed using a wavelet packet transform technique. A total of 60 high-speed machining experiments were performed, covering a range of cutting speed and feed rate conditions. The experimental results show that tool edge wear has a complex effect on the cutting vibrations. The vibration amplitudes in high-speed machining of Ti-6Al-4V can be higher or lower than those in high-speed machining of Inconel 718, depending on the particular cutting speed and feed rate employed. Analysis of variance reveals that both the cutting speed and the feed rate always play a statistically significant role in affecting the vibration amplitudes in all three directions, i.e., the cutting speed direction, the feed rate direction, and the depth of cut direction. It is also revealed that in high-speed machining of Ti-6Al-4V, four significant wavelet packets (W30, W32, W33, and W36) exist, depending on the particular cutting conditions employed. In high-speed machining of Inconel 718, two significant wavelet packets (W32 and W33) exist, regardless of the cutting conditions employed. The significant wavelet packets identified in part II of the present study can be used as features to detect and monitor tool edge wear in high-speed machining.

Diamond turning of small Fresnel lens array in single crystal InSb

A small Fresnel lens array was diamond turned in a single crystal (0 0 1) InSb wafer using a half-radius negative rake angle (−25°) single-point diamond tool. The machined array consisted of three concave Fresnel lenses cut under different machining sequences. The Fresnel lens profiles were designed to operate in the paraxial domain having a quadratic phase distribution. The sample was examined by scanning electron microscopy and an optical profilometer. Optical profilometry was also used to measure the surface roughness of the machined surface. Ductile ribbon-like chips were observed on the cutting tool rake face. No signs of cutting edge wear was observed on the diamond tool. The machined surface presented an amorphous phase probed by micro Raman spectroscopy. A successful heat treatment of annealing was carried out to recover the crystalline phase on the machined surface. The results indicated that it is possible to perform a ‘mechanical lithography’ process in single crystal semiconductors.

A comparative study of high-speed machining of Ti-6Al-4V and Inconel 718—part II: Effect of dynamic tool edge wear on cutting vibrations

A comparative study of high-speed machining of Ti-6Al-4V and Inconel 718—part II: Effect of dynamic tool edge wear on cutting vibrations

Study of the Wear of Drills in Dry Drilling of NM360 Steels

According to the characteristics of NM360, a contrast experiment for drilling performance in YG8 cemented carbide twist drill, high-speed steel twist drill and factories used in coating the ordinary high-speed steel twist drill has been done. Using microscope to observe tool wear, we found that the flank wear and chisel edge wear are the main wear of the drill. The carbide tools has a better ability of resistance to plastic deformation, abrasive wear and adhesive wear than high-speed steel cutting tools. The coating tools are better to resist abrasive wear and adhesive wear than uncoated tools.Deformation of carbide cutting tools, abrasive wear, ability than high-speed steel cutting tools.

Influence of regular and random cutting tool deformation on the cutting force of three-dimensional turning operation

The current work emphasises the impact of the various modes of cutting tool edge wear and failure on the different force components considering the three-dimension orthogonal continuous machining using multi-coated carbide tips. Edge force is usually attributed to the ploughing and rubbing actions on the tool-workpiece interface which, in turn are associated with the extent of the inevitable wear modes: nose, flank, and notch wear. Modelling of the experimental results using linear and non-linear regression analysis is established to qualitatively and quantitatively grasp the functional interrelation among the involved parameters. Results indicated that all force components are, to different extents, affected by all edge wear land modes. However, it is shown that each of the observed edge wear and failure has its own potential on specific force components and on specific cutting pressure.

El diagnóstico del pediatra ante la patología bucal benigna del recién nacido

Knowledge of oral pathology of the newborn is important for the pediatric odontologist and also for pediatricians in order to diagnose and adequately approach it. The newborn oral cavity has specific anatomical features which health care team must know how to identify benign oral conditions. The more common are: Bohn nod- ules, Epstein pearls, Fordyce granules, Riga Fede ulcer, eruption hematoma, candidiasis, herpes simplex, difficult dental eruption, lymphangioma, natal and neonatal teeth. For those teeth whether or no they have carried or worn edges should be pulled out if they affect oral function or if they are the cause of Riga Fede ulceration. Surgical treatment is also indicated for congenital epulis, mucocele, ranula and hemangioma. A successful treatment, is based on a good diagnosis and interdisciplinary treatment. This article briefly describes the most common oral conditions of newborns in order to orient the specialist (not the dentist) with practical recommendations for early and timely treatment.

G131011 無酸素銅精密切削におけるダイヤモンドエ具損耗特性 : 刃先先端部の窒素不純物と損耗の関係([G131]生産加工・工作機械部門,一般セッション)

G131011 無酸素銅精密切削におけるダイヤモンドエ具損耗特性 : 刃先先端部の窒素不純物と損耗の関係([G131]生産加工・工作機械部門,一般セッション)

Computational Study of the Effect of Cutting Speeds on Tool Wear during Machining of AISI 316L Steel

This research aims to study the effect of cutting speeds on wear behaviors of TiAlN coated insert during the machining process of AISI 316L steel. Experimental investigation and finite element method were employed. The two-dimensional (2D) plane strain orthogonal cutting model was focused at the initial continuous chip formation. The effect of cutting speeds, i.e. 50, 75,120 and 150 m/min, was studied. The tool wear behavior was then further investigated based on computational results which are temperature, von-mises equivalent stress, equivalent plastic strain and contact pressure. High temperature developed at rake face during high cutting speed, i.e. the cutting speed above 120 m/min, suggesting crater wear or diffusion wear. High equivalent plastic strain, i.e. greater than the fracture strain at failure of AISI 316L steel, were observed all along the tool edge around the contact area suggesting the built up edge (BUE) wear at all cutting speed investigated. The adhesive wear was expected on the edge radius at low cutting speed (50 to 75 m/min) based on the von-mises equivalent stress distributions. The overall severity of sliding wear was found to be around the tool nose due to high contact pressure in all cases. The experiments were also conducted with the tail stock constrained in all experiments to reduce the effect of vibration. The insert tool wear was examined by Scanning Electron Microscope. Wear was observed on flank face and rake face of the insert tools with different wear behavior at different cutting speed which agreed well with computational predictions.

Tool wear of coated drills in drilling CFRP

This study aimed to investigate the wear of certain coated drills when drilling carbon fiber reinforced composites (CFRP). Three different drills were used in the drilling experiments: uncoated, diamond coated and AlTiN coated carbide (WC–Co) drills. The tool wear in CFRP machining was quite different from that in conventional metal machining. The primary wear type was a dulling or blunting of the cutting edge, which has been referred to as edge rounding wear or edge recession. In this paper, a hypothesis has been developed to explain the edge rounding wear in CFRP machining. Due to the fracture-based chip formation of CFRP, there is lack of the work material stagnation zone in front of the cutting edge, which normally prevents the edge wear in metal machining. Series of wear lead to rapid dulling of the cutting edge. The resistance to edge rounding wear on the coated as well as uncoated drills has been investigated. The diamond coating significantly reduces the edge rounding wear. However, AlTiN coated drills showed no visible improvement over the uncoated carbide drill, despite of their high hardness, thus not protecting the drill. The wear mechanisms of the uncoated carbide drill and coatings are discussed. It is believed that the 2-body and 3-body abrasive wear fail to explain the observed tool wear in CFRP drilling. However, the wear of the coatings and uncoated carbide substrate from tribo-meter tests correlated well with the tool wear in the CFRP drilling. Therefore, the tribo-meter test can be used to screen the prospective tool materials before carrying drilling experiment.

Experimental observations on surface roughness, chip morphology, and tool wear behavior in machining Fe-based amorphous alloy overlay for remanufacture

Fe-based amorphous alloy, a new-type material, was developed as a special-purpose welt overlay for remanufacture. It was deposited on the worn-out part for resuming and upgrading part performance. The microstructure characteristics of the overlay was characterized, including microstructure, phase composition, thermostability, and microhardness. In order to get a comprehensive insight to the machining process of amorphous overlay, this paper presents an experimental investigation into the effect of various machining parameters and tool geometry (Edge) on the surface roughness, tool wear, chip morphology, and surface damage. Comparing larger rake angle of 15°and smaller nose radius of 0.4 mm with 5° and 0.8 mm at the same cutting parameters, we found that larger rake angle of 15° and smaller nose radius of 0.4 mm increased the Ra surface roughness parameter. In the tests, crater wear was not observed, and the friction and wear on the minor cutting edge wear were heavy due to the spring back of the machined surface. In brief,abrasion, adhesion, fatigue, and chipping are the main wear mechanism. As the feed rate reduced and the depth of cut increased (from feed rate = 0.06 mm/rev and depth of cut = 0.3 mm to feed rate = 0.09 mm/rev and depth of cut = 0.2 mm), a number of physical changes occurred in the chip including reduced distance between serrations, increased shear band angle, and changed chip morphology from spiral to ribbon shape. The results show that strain and strain rate rises in the chips’ inside with the increase in cutting temperature. When the thermal softening exceeded strain hardening, the shear resistance decreased rapidly. Thus, the free surface of the chip presents the nodular and lamella structure. It was noted that specimens generated by larger rake angle of 15° and smaller nose radius of 0.4 mm showed poor surface roughness as well as extensive surface damage.

Failure mechanisms of a PCD tool in high-speed face milling of Ti–6Al–4V alloy

High-speed milling tests were carried out on Ti–6Al–4V titanium alloy with a polycrystalline diamond (PCD) tool. Tool wear morphologies were observed and examined with a digital microscope. The main tool failure mechanisms were discussed and analyzed utilizing scanning electron microscope, and the element distribution of the failed tool surface was detected using energy dispersive spectroscopy. Results showed that tool flank wear rate increased with the increase in cutting speed. The PCD tool is suitable for machining of Ti–6Al–4V titanium alloy with a cutting speed around 250 m/min. The PCD tool exhibited relatively serious chipping and spalling at cutting speed higher than 375 m/min, within further increasing of the cutting speed the flank wear and breakage increased greatly as a result of the enhanced thermal–mechanical impacts. In addition, the PCD tool could hardly work at cutting speed of 1,000 m/min due to the catastrophic fracture of the cutting edge and intense flank wear. There was evidence of workpiece material adhesion on the tool rake face and flank face in very close proximity to the cutting edge rather than on the chipped or flaked surface, which thereby leads to the accelerating flank wear. The failure mechanisms of PCD tool in high-speed wet milling of Ti–6Al–4V titanium alloy were mainly premature breakage and synergistic interaction among adhesive wear and abrasive wear.