Evidence of Phase Dependent Tool Wear in Ti-6Al-4V Turning Experiments Using PCD and Carbide Inserts

2012 ◽  
Author(s):  
David J. Schrock ◽  
Patrick Kwon
Keyword(s):  
Phase Transformation ◽  
Tool Wear ◽  
Cutting Speed ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Rake Face ◽  
Work Material ◽  
Significant Difference ◽  
Pcd Tools ◽  
Cutting Speeds

This paper presents evidence of phase transformation in turning titanium work material and discusses its impact on tool wear. Tool wear of polycrystalline diamond inserts was studied in turning experiments on Ti-6Al-4V. Confocal laser scanning microscopy was conducted to analyze the rake face of the turning inserts. At cutting speeds of 61m/min, the rake face exhibited scalloped-shaped, fractured, uneven, and rough wear. This is characteristic of attrition wear. At cutting speeds of 122m/min, wear was smooth and even in nature, which is a typical characteristic of diffusion/dissolution wear. At a cutting speed of 91m/min, the wear was a combination of those observed at speeds of 61m/m and 122m/m. A comparison of the wear on the PCD tools to that of WC-6Co from earlier work is also discussed. A significant difference in wear existed between the two different cutting tool materials at the low cutting speed. This difference in wear was linked to a transition from alpha to beta phase in the titanium work material. Temperature estimates on the rake face of the tool previously extracted from FEM support the possibility of phase transformation at the cutting data tested.

Phase Dependent Tool Wear in Turning Ti-6Al-4V Using Polycrystalline Diamond and Carbide Inserts

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
David J. Schrock ◽  
Di Kang ◽  
Thomas R. Bieler ◽  
Patrick Kwon
Keyword(s):  
Phase Transformation ◽  
Tool Wear ◽  
Cutting Speed ◽  
Polycrystalline Diamond ◽  
Alpha Phase ◽  
Laser Scanning Microscopy ◽  
Phase Transformation Temperature ◽  
Rake Face ◽  
Work Material ◽  
Pcd Tools

Tool wear of polycrystalline diamond inserts was analyzed in turning experiments on Ti-6Al-4V. Evidence of phase transformation in turning titanium work material is presented and its impact on tool wear is discussed. Confocal laser scanning microscopy was used to analyze the rake face of the turning inserts. At cutting speed of 61 m/min, the rake face exhibited scalloped-shaped, fractured wear, characteristic of typical attrition wear. At cutting speed of 122 m/min, a smooth crater was observed, which is a typical characteristic of diffusion/dissolution wear. At the cutting speed of 91 m/min, the wear features were a combination of those observed at speeds of 61 m/min and 122 m/min. A comparison of the wear on the polycrystalline diamond (PCD) tools to that of WC-6Co from our earlier work is also discussed. Microstructural analysis of the of both the undeformed work material and the chip using electron-backscatter diffraction provided evidence to support the phase transformation. Temperature estimates on the rake face of the tool previously extracted from Finite Element Method (FEM) support the possibility of phase transformation at the high cutting speed tested. The difference in the wear pattern was also linked to the extent of recrystallization in the titanium work material. At 61 m/min there was more alpha phase in the work material without much recrystallization, which generated uneven scalloped wear. At 122 m/min, phase transformation of the existing alpha phase to the beta phase in the work material and recrystallization increased the dissolution/diffusion wear process.

An Analysis of the Wear of Tungsten Carbide and Polycrystalline Diamond Inserts Turning Ti-6Al-4V

2011 ◽  
Author(s):  
David Schrock ◽  
Xin Wang ◽  
Patrick Kwon
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Tool Wear ◽  
Flank Wear ◽  
Polycrystalline Diamond ◽  
Laser Scanning Microscopy ◽  
Rake Face ◽  
Crater Wear ◽  
Pcd Tools ◽  
Face Temperature

Dry turning experiments on Ti-6Al-4V were conducted using two grades (finer and coarser) of carbides and polycrystalline diamond (PCD) inserts to study tool wear. Despite of minor compositional difference between two carbide grades, both grades contain 6% Co. Crater wear and flank wear were measured using Confocal Laser Scanning Microscopy (CLSM). Three dimensional rake surface topographies were reconstructed from the CLSM data and wear profiles were extracted. Finite Element Analysis (FEA) was conducted to study the effects of cutting conditions and thermal properties on rake face temperature. Flank wear on the carbide tools indicated that the inserts with the finer grain size exhibited smaller flank wear than the insert of the coarser grain size. This was attributed to reduced abrasive wear in the finer grained inserts as a result of a higher hardness. The carbide grade with a coarser grain size had an enhanced ability to resist crater wear, likely from lower rake face temperatures and the differences in the compositions. It is known that coarser grain carbides have a higher thermal conductivity resulting from increased grain contiguity. FEA was used to study the temperature difference between the two grain-sizes and the effect of thermal conductivity on temperature gradients. Tool wear of the PCD inserts was also studied. The PCD tools showed significant adhesive wear at the 200sfm cutting speed, transitioning to crater wear at 400sfm. With a high thermal conductivity, it is possible that rake face temperatures were low enough to alter the wear mechanism. FEA supports this hypothesis, as the maximum rake face temperature for the PCD inserts were only around 900°C at 200sfm.

scholarly journals Wear and MnS Layer Adhesion in Uncoated Cutting Tools When Dry and Wet Turning Free-Cutting Steels

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 556 ◽  
Author(s):  
D. Martinez Krahmer ◽  
S. Hameed ◽  
A. J. Sánchez Egea ◽  
D. Pérez ◽  
J. Canales ◽  
...  
Keyword(s):  
Tool Wear ◽  
Cutting Tool ◽  
Wear Behavior ◽  
Manganese Sulfide ◽  
Cutting Speed ◽  
Hard Metal ◽  
Rake Face ◽  
Machined Surface ◽  
Eds Analysis ◽  
Cutting Speeds

Free-cutting steels are developed to produce large quantities of parts with low mechanical behavior, mainly for automotive sector. These alloys contain phosphorous, lead, sulfur, and manganese that help to improve the machinability and surface roughness. However, due to the toxicity of lead, steel mills in recent years have been focusing on non-toxic steels to produce minimum environmental pollution and better machinability. The present work investigates the tool wear during dry and wet turning of free-cutting steels (SAE 1212, SAE 12L14, and SAE 1215) by using uncoated hard metal inserts at three cutting speeds. Additionally, a EDS analysis was performed to determine the presence of Mn and S elements at the rake face of the cutting tool that can induce a higher adhesion of manganese sulfide (MnS). The results show that the SAE 12L14 steel has the best performance in terms of tool life at different cutting speeds. This difference is maximum at the lowest cutting speed, which gradually decreases with the increase of the cutting speed. The wear behavior is evaluated in the three steel alloys at each cutting speed and, consequently, the tool wear exhibits a slightly better performance in the dry machining condition for higher cutting speeds (180 and 240 m/min), independent of the steel alloy. Finally, EDS analysis confirms the presence of Mn and S elements at the rake face of the inserts machined in dry condition. Hence, MnS is expected to interpose between the machined surface and cutting tool surface to behave similar to tribofilm by reducing the wear on the cutting edge.

scholarly journals Wear Characteristics of Cutting Tool in Brittle Removal of a Ductile Meta in High-Speed Machining

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1679
Author(s):  
Guosheng Su ◽  
Yuhao Wang ◽  
Zhitao Han ◽  
Peirong Zhang ◽  
Hongxia Zhang ◽  
...  
Keyword(s):  
Tool Wear ◽  
Pure Iron ◽  
High Speed ◽  
Cutting Tool ◽  
Cutting Speed ◽  
Rake Face ◽  
Workpiece Material ◽  
Wear Characteristics ◽  
Ductile Metal ◽  
Cutting Speeds

The contact stress and heating effect between the cutting tool and workpiece in metal machining is symmetrical. However, the symmetry may be destroyed by changes in the workpiece material mechanical properties, such as ductility. The goal of this study is to reveal the wear characteristics of the cutting tool in machining a ductile metal with the cutting speed at which the metal is embrittled by the high-strain-rate-embrittle effect (HSREE). Orthogonal high-speed turning experiments were carried out. Pure iron type DT8 was cut at different cutting speeds, ranging from 1000 m/min to 9000 m/min. The shape and morphology of the chips obtained in the experiment were observed and analyzed by optical microscope and scanning electron microscope (SEM). Tool wear characteristics at different cutting speeds were observed. It shows that the pure iron becomes completely brittle when the cutting speed is higher than 8000 m/min. On the rake face, the coating of the cutting tool bursts apart and peels off. A matrix crack originates in the cutting edge or rake face and extends to the flank face of the cutting tool. The effects of HSREE on the tool wear is discussed. The findings of this study are helpful for choosing a suitable tool for brittle cutting of the ductile metal pure iron with very high cutting speed and solving the problems in machining due to its high ductility and high stickiness.

Use of confocal laser scanning microscopy and a computer model to understand ink cavitation and filamentation

TAPPI Journal ◽  
2010 ◽  
Vol 9 (10) ◽  
pp. 7-15
Author(s):  
HANNA KOIVULA ◽  
DOUGLAS BOUSFIELD ◽  
MARTTI TOIVAKKA
Keyword(s):  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Confocal Laser ◽  
Print Quality ◽  
Length Scale ◽  
Offset Printing ◽  
Significant Difference ◽  
Printing Speed

In the offset printing process, ink film splitting has an important impact on formation of ink filaments. The filament size and its distribution influence the leveling of ink and hence affect ink setting and the print quality. However, ink filaments are difficult to image due to their short lifetime and fine length scale. Due to this difficulty, limited work has been reported on the parameters that influence filament size and methods to characterize it. We imaged ink filament remains and quantified some of their characteristics by changing printing speed, ink amount, and fountain solution type. Printed samples were prepared using a laboratory printability tester with varying ink levels and operating settings. Rhodamine B dye was incorporated into fountain solutions to aid in the detection of the filaments. The prints were then imaged with a confocal laser scanning microscope (CLSM) and images were further analyzed for their surface topography. Modeling of the pressure pulses in the printing nip was included to better understand the mechanism of filament formation and the origin of filament length scale. Printing speed and ink amount changed the size distribution of the observed filament remains. There was no significant difference between fountain solutions with or without isopropyl alcohol on the observed patterns of the filament remains.

scholarly journals Micromorphological analysis and bond strength comparison of two adhesives for different degrees of dental fluorosis

2020 ◽  
Author(s):  
Shuangfeng Liu ◽  
Yanxia Zhu ◽  
Tana Gegen
Keyword(s):  
Shear Strength ◽  
Bond Strength ◽  
Bonding Strength ◽  
Laser Scanning ◽  
Dental Fluorosis ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Cohesive Failure ◽  
Bonding System ◽  
Significant Difference

Abstract The objective of this study was to analyze morphologically the all-etching bonding system and self-etching bonding system for enamel with different degrees of fluorosis and evaluate the bond strength of each system. Teeth that were indicated for extraction owing to orthodontic or periodontal problems were selected. According to Dean’s index and the Thylstrup-Fejerskov index, 180 extracted teeth were divided into three groups of mild, moderate, and severe dental fluorosis (DF), with 60 teeth in each group. The teeth in each group were randomly divided into two subgroups (n = 30), which were then subjected to the all-etching bonding system (Prime & Bond NT) and self-etching bonding system (SE-Bond). Each group of adhesives was used to bond Z350 universal resin (3M) to the etched dental enamel. Tensile and shear tests were conducted to determine the bond strength. Subsequently, the fractured specimens were investigated using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The Prime & Bond NT was statistically significant for the tensile and shear strength of enamel with mild fluorosis (P < 0.05) but did not exhibit a significant difference for moderate and severe DF (P > 0.05). The SE-Bond was not statistically significant for the tensile and shear strength of mild, moderate, or severe DF (P > 0.05). The SEM and CLSM results reveal that the mild fluorosis enamel crystals were relatively dense, and a small amount of resin remained. The moderate fluorosis enamel crystals were loosely arranged, and the gaps were widened. The severe fluorosis enamel crystals were irregularly arranged. The disorder was aggravated, and the dentinal orifice was exposed by partial enamel exfoliation. The bonding strength of mild fluorosis enamel with the Prime & Bond NT was better than that with the SE-Bond, and cohesive failure was the most common mode of failure. Because there was no difference in the bonding strength of the SE-Bond for different degrees of DF, we recommend the use of the all-etching adhesive system in the clinical treatment of teeth with mild fluorosis.

Effect of Cutting Temperature on Phase Transformation in Cutting of NiTi Alloy

2020 ◽  
Author(s):  
Hao Yang ◽  
Katsuhiko Sakai ◽  
Hiroo Shizuka ◽  
Kunio Hayakawa ◽  
Tetsuo Nagare
Keyword(s):  
Phase Transformation ◽  
Phase State ◽  
Niti Alloy ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Cutting Process ◽  
Maximum Temperature ◽  
Machined Surface ◽  
Speed Condition ◽  
Work Material

Abstract In this study, the effect of cutting temperature on phase transformation in cutting of room temperature austenitic NiTi alloy was investigated by X-ray diffraction (XRD) and temperature measurements. Results from XRD reveals that after cutting process, the phase state of work material near the machined surface transformed from austenite to martensite at relatively low cutting speed conditions while the phase state of work material did not undergo any form of transformation at the highest cutting speed condition. Temperature measurement results measured with temperature indicating paint showed that the maximum temperature of work material near the machined surface in cutting process exceeded the Md temperature at the highest cutting speed condition. However, there was no phase transformation observed in cutting chips after cutting at all cutting speed conditions as the temperature of cutting chips was much higher than the Md temperature under all cutting speed conditions.

scholarly journals Evaluation of four final irrigation protocols for cleaning root canal walls

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Qiang Li ◽  
Qian Zhang ◽  
Xiaoying Zou ◽  
Lin Yue
Keyword(s):  
Root Canal ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Smear Layer ◽  
Confocal Laser ◽  
Bacterial Survival ◽  
Bacterial Inhibition ◽  
Layer Removal ◽  
Significant Difference ◽  
Canal Systems

Abstract The aim of this study was to compare the efficiency of four final irrigation protocols in smear layer removal and bacterial inhibition in root canal systems. Thirty roots inoculated with Enterococcus faecalis were prepared with ProTaper Universal files. The teeth were disinfected by conventional needle irrigation, sonic agitation using the EndoActivator device, passive ultrasonic irrigation, or an M3 Max file. Teeth with no root canal preparation served as blank controls for the establishment of the infection baseline. Teeth with preparation but no final irrigation served as a post-instrumentation baseline. After the final irrigation, the teeth were sectioned in half. One half of each tooth was examined by scanning electron microscopy (SEM) to assess smear layer removal using a five-point scale. The other half was examined by confocal laser scanning microscopy (CLSM) using the LIVE/DEAD BackLight bacterial viability kit to evaluate the depth of bacterial survival in dentinal tubules. SEM analysis revealed no significant difference in smear layer removal throughout the whole canal among the EA, PUI, and M3 Max groups (P > 0.05). CLSM revealed that PUI achieved the greatest bacterial inhibition depth in the coronal ((174.27 ± 31.63) μm), middle ((160.94 ± 37.77) μm), and apical ((119.53 ± 28.49) μm) thirds of the canal (all P < 0.05 vs. other groups). According to this comprehensive SEM and CLSM evaluation, PUI appears to have the best infection control ability in root canal systems.

Feasibility Study of the Effectiveness of Cryogenically Treated Ceramic Inserts for Pocket Milling Maneuvers

2009 ◽  
Author(s):  
Justin L. Milner ◽  
Jeffrey A. Beers ◽  
John T. Roth
Keyword(s):  
Wear Resistance ◽  
Tool Wear ◽  
Feasibility Study ◽  
High Speed ◽  
Cryogenic Treatment ◽  
Cutting Speed ◽  
High Speed Steel ◽  
Initial Study ◽  
Machining Processes ◽  
Cutting Speeds

Machining is a popular and versatile manufacturing process that is widely used in today’s industry when producing metallic parts; however, limited tool life can make this an expensive and time consuming fabrication technique. Consequently, methods that decrease the rate of tool wear and, thus, increase tool longevity are a vital component when improving the efficiency of machining processes. To this end, cryogenically treating cutting tools (especially high-speed steel tooling) is becoming more commonplace since research has shown that the treated tooling exhibits significantly higher wear resistance. At this point, however, the effect of cryogenic treatments on ceramic tooling has not been established. Considering this, the research herein presents a feasibility study on the effectiveness of using cryogenic treatments to enhance the wear resistance of WG-300 whisker-reinforced ceramic cutting inserts. To begin, the effect of the cryogenic treatment on the insert’s hardness is examined. Subsequently, tool wear tests are conducted at various cutting speeds. Through this study, it is shown that cryogenically treating the ceramic inserts decreases the rate of tool wear at each of the cutting speeds that were tested. However, the degree of wear resistance introduced by cryogenically treating the inserts proved to be highly dependent on the cutting speed, with slower speeds exhibiting greater improvements. Thus, based on this initial study, the cryogenic treatment of ceramic tooling appears to produce beneficial results, potentially increasing the overall efficiency of machining processes.

High Speed Machining: A Review from a Viewpoint of Chip Formation

2011 ◽  
Vol 188 ◽  
pp. 578-583 ◽  
Author(s):  
Toshiyuki Obikawa ◽  
Masahiro Anzai ◽  
Tsuneo Egawa ◽  
Norihiko Narutaki ◽  
Kazuhiro Shintani ◽  
...  
Keyword(s):  
Tool Wear ◽  
Life Span ◽  
High Speed ◽  
Cutting Speed ◽  
Strong Nonlinearity ◽  
High Speed Machining ◽  
Cast Irons ◽  
Sliding Test ◽  
Cutting Experiments ◽  
Cutting Speeds

This paper describes strong nonlinearity in log V-log L relationship, which is often found in machining of supperalloys, titanium alloys, hardened steels, cast irons, etc. The nonlinearity plays an important and favorable role in extension of life-span cutting distance at higher cutting speeds; that is, in a certain range of cutting speed, life-span cutting distance increases with cutting speed. Results of tool wear in a sliding test and cutting experiments, which showed the evidences of strong nonlinearity, were investigated and the mechanisms causing the nonlinearity were discussed.

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