Chronological developments in Cutting Tool MaterialsBilal Syed
This is ap resentation showing the developments of cutting tools materials used from early life to present. their materials, properties, advantages, etc.
This slide describes two essential elements in machining operations:
cutting-tool materials and cutting fluids.
° The slide opens with a discussion of the types and characteristics of cutting tool materials.
° The properties and applications of high-speed steels, carbides, ceramics, cubic boron nitride, diamond, and coated tools are described in detail.
The types of cutting fluids in common use are then described, including their functions and how they affect the machining operation.
° Trends in near-dry and dry machining are also discussed, and their importance with respect to environmentally friendly machining operations are explained.
The selection of cutting-tool materials for a particular application is among the most important factors in machining operations, just as the selection of mold and die
materials was critical for forming and shaping processes . We will discuss throughout this slide the relevant properties and performance characteristics of all major types of cutting-tool materials, which will help us in tool selection.
However, as it will become apparent, the complex nature of this subject does not always render itself to the determination of appropriate tool materials; hence, we also must rely on general guidelines and recommendations that have been accumulated in industry over many years.More detailed information on tool material recommendations for specific workpiece materials and machining operations will be presented.
As noted, the cutting tool is subjected to
(a) high temperatures,
(b) high contact stresses, and
(c) rubbing along the tool-chip interface and along the machined surface.
Consequently, the cutting-tool material must possess the following characteristics:
° Hot hardness, so that the hardness, strength, and wear resistance of the tool are maintained at the temperatures encountered in machining operations. This property ensures that the tool does not undergo any plastic deformation and thus retains its shape and sharpness.
Toughness and impact strength (or mechanical shock resistance), so that impact forces on the tool that are encountered repeatedly in interrupted cutting operation (such as milling and turning a splined shaft on a lathe) or forces due to vibration and chatter during machining do not chip or fracture the tool.
Thermal shock resistance, to withstand the rapid temperature cycling encountered in interrupted cutting.
Wear resistance, so that an acceptable tool life is obtained before replacement is necessary.
Chemical stability and inertness with respect to the material being machined, to avoid or minimize any adverse reactions, adhesion, and tool-chip diffusion that would contribute to tool wear.
Chronological developments in Cutting Tool MaterialsBilal Syed
This is ap resentation showing the developments of cutting tools materials used from early life to present. their materials, properties, advantages, etc.
This slide describes two essential elements in machining operations:
cutting-tool materials and cutting fluids.
° The slide opens with a discussion of the types and characteristics of cutting tool materials.
° The properties and applications of high-speed steels, carbides, ceramics, cubic boron nitride, diamond, and coated tools are described in detail.
The types of cutting fluids in common use are then described, including their functions and how they affect the machining operation.
° Trends in near-dry and dry machining are also discussed, and their importance with respect to environmentally friendly machining operations are explained.
The selection of cutting-tool materials for a particular application is among the most important factors in machining operations, just as the selection of mold and die
materials was critical for forming and shaping processes . We will discuss throughout this slide the relevant properties and performance characteristics of all major types of cutting-tool materials, which will help us in tool selection.
However, as it will become apparent, the complex nature of this subject does not always render itself to the determination of appropriate tool materials; hence, we also must rely on general guidelines and recommendations that have been accumulated in industry over many years.More detailed information on tool material recommendations for specific workpiece materials and machining operations will be presented.
As noted, the cutting tool is subjected to
(a) high temperatures,
(b) high contact stresses, and
(c) rubbing along the tool-chip interface and along the machined surface.
Consequently, the cutting-tool material must possess the following characteristics:
° Hot hardness, so that the hardness, strength, and wear resistance of the tool are maintained at the temperatures encountered in machining operations. This property ensures that the tool does not undergo any plastic deformation and thus retains its shape and sharpness.
Toughness and impact strength (or mechanical shock resistance), so that impact forces on the tool that are encountered repeatedly in interrupted cutting operation (such as milling and turning a splined shaft on a lathe) or forces due to vibration and chatter during machining do not chip or fracture the tool.
Thermal shock resistance, to withstand the rapid temperature cycling encountered in interrupted cutting.
Wear resistance, so that an acceptable tool life is obtained before replacement is necessary.
Chemical stability and inertness with respect to the material being machined, to avoid or minimize any adverse reactions, adhesion, and tool-chip diffusion that would contribute to tool wear.
Classification of Tool Materials.
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Cutting of hardened steel is a topic of high interest for toda 's industrial production and scientific research.
Machine parts consisting of hardened steel are high peiormance components which are often loaded
near their physical limits. The functional behavior of machined parts is decisively influenced by the fine
finishing process which represents the last step in the process chain and can as well be undertaken by
cutting as grinding. An overview of the mechanisms of chip removal in hard cutting and the thermomechanical
influence of the work area is presented. Furthermore, several models of chip removal in hard
turning are introduced and discussed summarizing the metallurgical fundamentals and giving an overview
on stress and temperature distributions in the work area. Boundary conditions for hard cutting as e.g.
machine tools, cutting materials and others are subject to discussion to determine the achievable
workpiece quality and economic efficiency of hard cutting processes in comparison with grinding.
Unit 2 Machinability, Cutting Fluids, Tool Life & Wear, Tool MaterialsMechbytes
Concept of machinability, machinability index, factors affecting machinability
Different mechanism of tool wear types of tool wear (crater, flank etc.), Measurement and control of tool wear
Concept of tool life, Taylor's tool life equation (including modified version)
Different tool materials and their applications including effect of tool coating
Introduction to economics of machining
Cutting fluids: types, properties, selection and application methods
In this report the basic design principles and the current state-of-the-art for cutting tools specially designed to be applied on difficult-to-cut materials are described. One by one, the main aspects involved in tool design and construction will be explained in depth over the following sections, completing a general view of the tool world, to provide easy comprehension of the whole book. Materials for the substrates, coatings, and geometry are explained, with special attention to recent developments. A section is devoted to new machining techniques such as high-feed and plunge milling, turn milling and trochoidal milling.
Mechanism of Fracture in Friction Stir Processed Aluminium AlloyDr. Amarjeet Singh
Aluminium alloys are used for important
applications in reducing the weight of the component and
structure particularly associated with transport, marine,
and aerospace fields. Grain refinement by scandium (Sc)
addition can eliminate the casting defects and increase the
resistance to hot tearing for high strength aluminium alloys.
FSP for cast aluminium alloys have been focused and it has
great advantages including solid state microstructural
evolution, altering mechanical properties by optimizing
process parameters. These parameters are tool rotational
speeds (720, and 1000 rpm), traverse speeds (80, and 70
mm/min), and axial compressive force at 15 kN, etc. The
mechanical properties had been evaluated on FSPed
aluminium alloy with different microstructural conditions.
Fracture properties of aluminium alloys are very important
for industrial applications. Tensile and fracture toughness
properties were correlated to microstructural and
fractographic features of the aluminium alloys need to
explore their essential failure mechanisms.
Classification of Tool Materials.
For More Details
Subscribe to My YOUTUBE CHANNEL
Engineering Study Materials : https://www.youtube.com/channel/UC8vigo0VxccfcGnmJnf-ESA
Cutting of hardened steel is a topic of high interest for toda 's industrial production and scientific research.
Machine parts consisting of hardened steel are high peiormance components which are often loaded
near their physical limits. The functional behavior of machined parts is decisively influenced by the fine
finishing process which represents the last step in the process chain and can as well be undertaken by
cutting as grinding. An overview of the mechanisms of chip removal in hard cutting and the thermomechanical
influence of the work area is presented. Furthermore, several models of chip removal in hard
turning are introduced and discussed summarizing the metallurgical fundamentals and giving an overview
on stress and temperature distributions in the work area. Boundary conditions for hard cutting as e.g.
machine tools, cutting materials and others are subject to discussion to determine the achievable
workpiece quality and economic efficiency of hard cutting processes in comparison with grinding.
Unit 2 Machinability, Cutting Fluids, Tool Life & Wear, Tool MaterialsMechbytes
Concept of machinability, machinability index, factors affecting machinability
Different mechanism of tool wear types of tool wear (crater, flank etc.), Measurement and control of tool wear
Concept of tool life, Taylor's tool life equation (including modified version)
Different tool materials and their applications including effect of tool coating
Introduction to economics of machining
Cutting fluids: types, properties, selection and application methods
In this report the basic design principles and the current state-of-the-art for cutting tools specially designed to be applied on difficult-to-cut materials are described. One by one, the main aspects involved in tool design and construction will be explained in depth over the following sections, completing a general view of the tool world, to provide easy comprehension of the whole book. Materials for the substrates, coatings, and geometry are explained, with special attention to recent developments. A section is devoted to new machining techniques such as high-feed and plunge milling, turn milling and trochoidal milling.
Mechanism of Fracture in Friction Stir Processed Aluminium AlloyDr. Amarjeet Singh
Aluminium alloys are used for important
applications in reducing the weight of the component and
structure particularly associated with transport, marine,
and aerospace fields. Grain refinement by scandium (Sc)
addition can eliminate the casting defects and increase the
resistance to hot tearing for high strength aluminium alloys.
FSP for cast aluminium alloys have been focused and it has
great advantages including solid state microstructural
evolution, altering mechanical properties by optimizing
process parameters. These parameters are tool rotational
speeds (720, and 1000 rpm), traverse speeds (80, and 70
mm/min), and axial compressive force at 15 kN, etc. The
mechanical properties had been evaluated on FSPed
aluminium alloy with different microstructural conditions.
Fracture properties of aluminium alloys are very important
for industrial applications. Tensile and fracture toughness
properties were correlated to microstructural and
fractographic features of the aluminium alloys need to
explore their essential failure mechanisms.
Study of Pitting Corrosion Behavior of FSW weldments of AA6101- T6 Aluminium ...IJERA Editor
Friction Stir Welding (FSW) is a promising solid state joining process widely used generally for Al alloys,
especially in aerospace, marine and automobile applications. In present work, the microstructure and corrosion
behavior of friction stir welded AA6101 T6 Al alloy is studied. The friction stir welding was carried using
vertical milling machine with different tool rotational speeds and welding speeds. The microstructure at weld
nugget or stir zone (SN), thermo-mechanically affected zone (TMAZ), heat affected zone (HAZ) and base metal
were observed using optical microscopy. The corrosion tests of base alloy and welded joints were carried out in
3.5% NaCl solution at temperature of 30º C. Corrosion rate and emf were determined using cyclic polarization
measurement.
high speed milling of Titanium Alloy toward Green manufactringalilimam
The machining process of titanium alloys always need special control by using coolant and
lubricant as it is one of the difficult-to-cut materials. To achieve green cutting of titanium alloy
Ti-6Al-4V with water vapor cooling and lubricating, a minitype generator is developed. Compared to
dry and wet cutting, the using of water vapor decreases the cutting force and the cutting temperature
respectively; enhances the machined surface appearance. Water vapor application also improves
Ti-6Al-4V machinability. The excellent cooling and lubricating action of water vapor could be
summarized that water molecule has polarity, small diameter and high speed, can be easily and
rapidly to proceed adsorption in the cutting zone. The results indicate that the using of water vapor has
the potential to attain the green cutting of titanium alloy instead of cutting floods.
Introduction
Experimental Investigations on Tribiological Properties of 6061-T6 Al Alloy b...IJAEMSJORNAL
Microstructure and tribological properties of Al-TiB2 nano surface composite fabricated by Friction Stir Processing (FSP) were evaluated. To vary the percentage of TiB2 three different slot thickness viz. 1mm, 1.5 mm and 2mm were considered. Microstructural evaluations showed a nearly uniform distribution of TiB2 in the aluminium matrix after FSP with the addition of composite powder. Microhardness test results shoes FSW of Al6061-T6 alloy with 2mm groove width has more hardness. tribological properties were evaluated at two different sliding velocities 0.314m/s and 0.48m/s and results shows that at lower loads there is no much difference in wear rate of surface composite made with different slot sizes but with increase in load and sliding velocity wear rate was increased , however, larger slot Al6061-TiB2 Surface composites show better wear resistance.
Surface hybrid nanocomposites via friction stir processingmohammed noor
Friction stir Processing (FSP) is a new innovative technology developed based on the principle of Friction Stir Welding (FSW) technique.
In FSP, the ceramic particulates are reinforced into the base metal by adding it into the groove and Friction Stir Processing (FSP) is performed.
In this study, the aluminum alloy 6061 is chosen as the base metal, alumina and graphite Nano powder as reinforcement.
The process parameters such traverse speed of 64 mm/min and the tool rotational speed of 1060 rpm and tilt angle of 2deg were selected, The Friction Powder Processing was carried out on vertical milling machine.
New parameters such as powder type and number of passes were involved and we also study the effect of heat treatment.
The influence of FSP was checked using some tests such as the microstructure analysis that was carried out using optical microscope (OM) and the mechanical characteristics were analyzed using tensile test and hardness test.
The micrograph results revealed that powder particulates were evenly distributed in the stir zone and reduction in grain size also observed; the reason for the grain size reduction was stirring action of the FPP tool’s pin.
The tensile strength results showed a significant improvement in strength by a percent of
50% compared to base metal but when T6 heat treatment is applied, the tensile strength decreased.
A low-carbon steel wire of AISI 1022 is used to easily fabricate into self-drilling tapping screws,
which are widely used for construction works. The majority of carbonitriding activity is performed to improve
the wear resistance without affecting the soft, tough interior of the screws in self-drilling operation. In this
study, Taguchi technique is used to obtain optimum carbonitriding conditions to improve the mechanical
properties of AISI 1022 self-drilling tapping screws. The carbonitriding qualities of self-drilling tapping screws
are affected by various factors, such as quenching temperature, carbonitriding time, atmosphere composition
(carbon potential and ammonia level), tempering temperature and tempering time. The quality characteristics of
carbonitrided tapping screws, such as case hardness and core hardness, are investigated, and so are their
process capabilities. It is experimentally revealed that the factors of carbonitriding time and tempering
temperature are significant for case hardness. The optimum mean case hardness is 649.2HV. For the case
hardness, the optimum process-capability ratio increases by about 200% compared to the original result. The
new carbonitriding parameter settings evidently improve the performance measures over their values at the
original settings. The strength of the carbonitrided AISI 1022 self-drilling tapping screws is effectively improved.
1-1 Influence of Multi Extrusion Die Process on Mechanical and Chemical Behav...Ahmed Ibrahim Razooqi
INFLUENCE OF MULTI EXTRUSION DIE PROCESS ON MECHANICAL
AND CHEMICAL BEHAVIOR OF 2024-T3 ALLOY.
Ahmed Ibrahim RAZOOQI
Technical Engineering College - Baghdad, Middle Technical University, Baghdad, IRAQ
The behaviour of materials in machining the influence of small tellurium ad...Lepuufu
The behaviour of materials in machining - the influence of small tellurium additions on the microstructure and machining behaviour of low carbon free cutting steels
Historical analysis of metal cutting shows that metal removal rates have been increasing in the course of the century, predicated by the advancement in tool materials but the steel design has lagged behind. This paper examines the mechanisms of chip formation and tool wear as a function of cutting speed in metal cutting. Chemical wear is identified as the dominant mechanism of tool wear at high cutting speeds caused by temperature rise due to shear localisation in the primary and secondary shear zones of chip. Shear localisation in the primary shear zone is shown to be influenced by both microstructural parameters, i.e. matrix hardening and second phase particles, and metal cutting variables, i.e. cutting speed (strain rate) and feed (pressure).
Influence of tellurium addition on drilling of microalloyed steel (din 38mns6)Lepuufu
Purpose – This paper seeks to evaluate the influence of tellurium content on the machinability of the microalloyed pearlitic steel (DIN 38MnS6).
Two grades of steels were used, one with high (27 times greater) tellurium content and one with a low tellurium content. Machinability of the steel was
determined by the number of holes drilled by the tool before undergoing severe deformation. The drilling test matrix was prepared using a fractional
factorial design with five input variables studied at two levels (25-1). Other variables investigated include cutting speed (45 and 60 m/min), feed rate
(0.15 and 0.25 mm/rev), geometry of the twist drills and use of minimum quantity lubrication (MQL) at the flow rates of 30 and 100 ml/h. Statistical
analysis of the results revealed that composition of the work material was most influential on tool performance. Addition of tellurium to the steel
significantly improved machinability, increasing the number of drilled holes by over 100 per cent. The MQL flow rate was the least influential as increase
in the flow from 30 to 100 ml/h reduced drill life only by about 9 per cent.
Design/methodology/approach – The drilling tests were carried out in the vertical position, up-down, without pre-holes (full drilling). Cutting
speeds of 45 and 60 m/min and feed rates of 0.15 and 0.25 mm/rev were employed. Drills with two sharpening types were tested. Cutting fluid used
was vegetable based and applied using the MQL technique at flow rates of 30 and 100 ml/h. The rejection criterion adopted was severe deformation of
the drills and the number of machined holes was used to measure the machinability of the material.
Findings – Of all the variables investigated in this study, the least influential on drill performance is the MQL flow rate. Increase in the flow rate from
30 to 100 ml/h reduced drill performance by 9 per cent, contrary to expectation. This is a result of the cooling-lubricant action balance promoted by the
cutting fluid applied in low quantities (MQL). The most influential variable on drill performance is addition of Te to the work material which gave over
twofold (103 per cent) improvement in drill performance at the cutting conditions investigated. The Te particles act at the chip-tool interface, reducing
the work necessary to shear the material during chip formation. Increase in both the cutting speed and the feed rate both lowered drill performance
during machining due to associated increase in cutting temperature which tended to accelerate thermally related wear mechanisms.
Originality/value – This work was conducted to evaluate the machinability of a novel alloyed steel employed in the automobile industry. Drilling was
considered as most automobile components especially the engine block is designed with many holes which require drilling process.
Desenvolvimento de aço com usinabilidade melhoria para moldes para plástico d...Lepuufu
A fabricação de moldes de grande porte exige a produção na aciaria de lingotes de
dimensões acima do usual. De forma a garantir a polibilidade do produto acabado, o material
não pode apresentar forte segregação, nível elevado de inclusões não metálicas ou
porosidades. Para tanto, é necessária a obtenção de reduzidos teores de enxofre e a execução
de elevada deformação mecânica no processo de conformação, principalmente em se
tratando de grandes lingotes. Contudo, a redução do teor de enxofre prejudica a
usinabilidade o que, sem outras alterações, encarece a fabricação do molde. Neste trabalho, é
apresentada a tecnologia de fabricação do bloco para o maior molde já produzido com aço
manufaturado no Brasil no qual o teor de enxofre foi reduzido abaixo de 50 ppm e a
usinabilidade foi mantida através da modificação da morfologia das inclusões através da
desoxidação por cálcio.
Surface residual stresses in machined austenitic stainless steelLepuufu
Surface residual stresses due to turning operations in AISI 304 type stainless steel were studied as a function of machining speed, feed rate,
depth of cut, and tool geometry and coating. Residual stress tensors were determined using X-ray diffraction technique. The effects of turning
conditions and tool on the residual stresses were discussed in terms of mechanically and thermally induced non-homogeneous plastic
deformation of the surface layers of the workpiece.
Determining the influence of cutting fluids on tool wear and surface roughnes...Lepuufu
Knowledge of the performance of cutting fluids in machining different work materials is
of critical importance in order to improve the efficiency of any machining process. The
efficiency can be evaluated based on certain process parameters such as flank wear, surface
roughness on the work piece, cutting forces developed, temperature developed at the tool
chip interface, etc. The objective of this work is to determine the influence of cutting fluids
on tool wear and surface roughness during turning of AISI 304 with carbide tool. Further
an attempt has been made to identify the influence of coconut oil in reducing the tool
wear and surface roughness during turning process. The performance of coconut oil is also
being compared with another two cutting fluids namely an emulsion and a neat cutting oil
(immiscible with water). The results indicated that in general, coconut oil performed better
than the other two cutting fluids in reducing the tool wear and improving the surface finish.
Coconut oil has been used as one of the cutting fluids in this work because of its thermal
and oxidative stability which is being comparable to other vegetable-based cutting fluids
used in the metal cutting industry.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
This pdf is about the Schizophrenia.
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Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
2. 26
possible to achieve all these properties, some of which are mutually exclusive, in
a single material.
For this reason many high temperature resistant tool materials have been
developed in the last ten years, such as various coatings and ceramics.
Several refractory coatings have been developed. These include single coat-
ings of TiC, TiN, A1203,HfN or HfC, and multiple coatings of A12O3 or TiN on
top of TiC. Chemical vapour deposition is the technique commonly used in the
coating process. [1,2].
More recently, ceramics have been introduced as tool materials for a wide
range of high-speed finishing and high-removal rate machining operations.
Ceramics are predominantly alumina-based materials, although silicon-
based materials are just beginning to appear with attractive features for certain
applications. These alumina-based materials mainly include oxide-based mate-
rials, such as A1203-ZrO2 and mixed-based materials, such as A1203-TiN-TiC-
ZrO2 [3,4,5,6]. But relatively recently this group has been supplemented by
nonoxide ceramic cutting tool materials, those composed of silicon nitride
[4,7,8].
Moreover in the last three years, 'whiskers' reinforced ceramic material, has
been commercially available. This is a ceramic matrix reinforced with extremely
strong, maximum tensile strength 7GPa, stiff single silicon carbide crystals
(0.3pro diameter, 20-50~m long) commonly called 'whiskers' [9,10,11].
Another ceramic material, now available, is alumina in submicron grain
which is toughened by ZrO~. phase transformation. The effect of phase
transformation toughening is that cracks which starts to propagate in the
material is arrested before the crack grows large enough to allow insert
breakage [12]. Finally the cubic boron nitride can be used to efficently and
economically machine some materials which are difficult to machine at high
speeds and with a high removal rate [13,14].
A lot of the ceramic materials mentioned earlier have been tested for wear
with cast iron and some difficult to machine materials with different cutting pa-
rameter. Therefore it has been very difficult to make a wear performance com-
parison [3,4,5,6,7,15].
The quantity of the steel worked by machine-tools is comparable with the
quantity of cast iron also worked by machine-tools [16]. It is therefore
significant to understand the performance of ceramic material when cutting
steel.
Consequently the purpose of this paper is to refer to the performance of ce-
ramic materials when cutting steel in continuous turning at high speed.
2. I~PERIMENTAL SECTION
A set of tool life tests in continuous dry turning conditions was performed on
AISI 1040 steel whose characteristics are reported in Tab.1. The material
3. 27
worked was supplied as a commercial tube with an outer diameter of 244mm
and an inner one of 144ram. A piece of this tube, approximately 600ram long,
was fixed between chuck and tailstock.
Table 1
Characteristics of AISI 1040 steel
Chemical composition:
Tensile strength:
Hardness:
C=0.43%, Mn=0.76%, Si=0.28%, S=0.027%, P=0.016%
R=620 N/mm2
HBN(2.xls~.5) = 182
All tests were carried out with a Boehringer DM 550/1000 lathe.
The cutting tool materials, selected for tests, for inserts SNGN 120408 were
the following:
sintered carbide grade P10 (WC-TiC-Co), in the following called "C";
silicon nitride (SisN4), in the following "S";
alumina based (A12Oa-ZrO2),in the following "F";
- mixed-based alumina (A12Oa-TiN-TiC-ZrO2), in the following "Z";
alumina reinforced with SiC whiskers (A1203-SiCw), in the following "W";
alumina based material (A1203-ZrO0, in submicron grain in the following "G";
cubic boron nitride (BN), in the following "B".
The room temperature characteristics of such tool materials are reported
in Tab. 2
These inserts were mounted on a commercial tool holder having the
following geometry:
- rake angle 7=-6°
- clearance angle a= 6°
- side cutting edge angle ~V=75°
- inclination angle ~.=-6°
Each cutting tool material was tested three times, with each of the following
cutting conditions:
- depth of cut d=2.00mm;
- feeds f equal: 0.224mm/rev, 0.28mm/rev;
- speeds V equal: 5.5m/sec, 7.8m/sec, 11m/sec.
In each test the cutting tool wear level was periodically submitted first to a
classical control by profilometer and after to observation of rake face and flank
by a TV camera. Each image of the cutting tool observed in this way was
digitized by a real time video digitizer board. Finally the image so obtained was
stored in an optical W.O.R.M. disk. With this technique it is always possible, to
measure the flank wear and to observe and control the crater dimensions.
Moreover the cristallografic and microstructural features were determined
by the X-ray diffractometry and SEM microscopy.
4. 28
Table 2
Room temperature characteristics of tool materials employed
Characteristcs Units C S Z F W G B
Density Kg/m3 12000 3200 4200 3800 3700 4300 3500
15000 3400 4300 4500 3800 4200
Vickers GPa 17 15 20 17 19 40
Hardness 19 21 24 21 21 60
VHmeasured GPa 15.2 15.5 18 17 19.5 17 25
Young's GPa 550 300 360 340 390 366 680
Modulus 600 380 420 400 400
Poisson's 0.22 0.25 0.21 0.24 0.23 0.23 0.22
Ratio 0.27 030
UltimateTensile GPa 1.0 0.4 0.35 0.24 0.45
Strength 2.0 0.35
Ultimate Comp. GPa 4.5 2.5 4.4 2.8
Strength 5.0 4.0
Trasverse Rupt. GPa 1.7 0.60 0.6 0.6 0.55
Strength 2.8 0.95 0.9 0.9 0.72
Fracture MN/m~5 10 5 4.0 4 8.5 5.25
Toughness 17 7 5.5 6 9.0
Thermal 10~/oC 5 3.0 7 7.8 6 5.5 3.6
7 4.8 9 8.6 7 5.6
Expansion
Thermal Wm/m~°C 50 30 20 20 16.5 38
Conductivity 50 30 30
An EDAX equipment, coupled with a scanning electron microscope, was
used to perform qualitative chemical analysis of some microstructural details.
The mentioned techniquies were also used to study the aspect of the cutting
zones and the fracture surfaces.
In Tab. 3a and 3b tool life values and Taylor's constants for ceramic materi-
als "G"; "F" and "Z" which showed the best performances were reported.
In Tab. 4 the average tool lives for ceramic materials "S", "C", "B" and "W"
were reported. These latter ceramic materials have shown poor wear resistance.
Fig. 1 and 2 report the tool life - cutting speed relationship for both feeds,
for ceramic materials "G","F" and "Z" for both wear criteria.
5. 29
3. ANALYSIS OF THE RESULTS
From Tab. 3a, 3b and 4 we can infer that the ceramic materials, "F", "G" and
"Z" have shown the best performances. Moreover these ceramic materials at the
highest speed, llm/sec, have shown a tool life between 180 and 300 seconds.
Table 3a
Tool life, in seconds, and Taylor's constants for some ceramic materials, for vari-
ous cutting speeds and feeds, with crater depth criterion Kt/Km=0.1
Mat. Feeds CUTTING SPEEDS [m/sec] Taylor's Statistics
[ram/my] constants
5.5 7.8 11 n C R2 F P
G 0.280
0.224
F 0.280
0.224
Z 0.280
0.224
1552 1620 1710
1700 1800 1895
1423 1430 1598
2146 2150 2346
1128 1140 1146
1561 1690 1753 !
451 470 485
573 650 694
400 466 585
340 364 510
360 395 438
420 431 504
180 200 240
289 300 325
301 305 335
180 230 270
163 170 248
181 194 155
0.33 63 0.98 9.76o.o2
0.39 100 0.99 7.53o.o4
0.45 136 0.92 16.5o.oI
0.30 54 0.91 20.6o.oI
0.39 82 0.97 2.22o.19
0.31 56 0.99 6.970.04
Tab. 3b
Tool life, in seconds, and Taylor's constants for some ceramic materials, for vari-
ous cutting speeds and feeds, with flank wear criterion Vb=0.3
Mat. Feeds CUTTING SPEEDS [m/sec] Waylor's Statistics
[mm/rev] constants
5.5 7.8 11 n c R2 F P
G 0.280
0.224
F
Z
0.280
0.224
0.280
0.224
1108 1340 1537
1144 1236 1398
919 1047 1097
974 1017 1088
836 931 953
964 1024 1063
501 585 671
533 584 675
538 576 593
445 482 534
470 484 488
454 465 472
240 277 331
330 344 383
382 393 420
315 346 356
220 237 255
214 244 268
0.45 139 0.96 0.11o.75
0.54 256 0.97 2.12o.19
0.76 1064 0.97 5.44o.o6
0.63 4.03 0.95 13.7o.ol
0.52 187 0.99 1.01o.35
0.48 147 0.99 1.36o2.s
These perfomances are the best among all the ceramic materials tested but they
are not sufficient.The same ceramic materials, "F", "G" and "Z",have shown a
6. 30
good wear resistance at 7.8m/sec and 5.5m/sec, with both feeds. From Tab. 3a
and 3b we can also observe that the tool life of "F", "G" and "Z", with flank wear
criterion Vb=0.3 is longer, more or less equal or shorter than tool life with crater
depth criterion Kt/Km=0.1, for the highest medium and lowest speed
respectively. This is caused, as is known, by the more rapid growth of crater
depth than that of wear land.
Table 4
Average tool life, in seconds, for some ceramics materials, for various cutting
speeds and feeds with crater wear (Kt/Km=0.1) and flank wear (VB=0.3) criteria
Tool life criterion Kt/Km=0.1 Tool life criterion Vb=0.3
Cutting Feeds Cutting Speeds Feeds Cutting Speeds
Materials [mngrev] [m/sec] [mndrev] [ndsec]
5.5 7.8 11 5.5 7.8 11
S 0.280 10 3 1 0.280 13 4 2
0.224 15 4 1 0.224 15 4 2
C 0.280 150 10 1 0.280 500 30 4
0.224 200 27 3 0.224 800 90 12
B 0.280 180 100 20 0.280 240 150 30
0.224 400 110 21 0.224 350 120 28
W 0.280 400 300 150 0.280 400 300 180
0.224 500 350 200 0.224 480 300 140
In cutting tool "F" the X-ray diffractometer and the SEM examination
revealed the presence of approximately 7-10 vol.% of tetragonal zirconia; the
inclusions size ranged from 0.4 to 1 microns. The SEM analysis showed also the
presence of smooth fracture surfaces in the tool nose. The aspect of these
surfaces is similar to the one of the metallic particles pasted into the cutting
zone; moreover the EDAX analysis revealed, in these zones, a high iron
concentration. We suppose that these fractures can be imputed to the oxidation
of the steel penetrated into the cracks during the turning tests. This hypothesis
is corroborated by the examination of a macrocrack propagating from the
chamfer into the ceramic insert ( see Fig.3 and Fig.4 with distribution map of
the iron).
The microstructure analysis of ceramic material "G" showed the presence of
20-25 vol.% of tetragonal zirconia. The SEM examination of the cutting zone
revealed also in this case the presence of the chemical wear and fracture
surfaces covered by a steel layer. Large cracks in the crater bottom were also
observed.
The SEM examination of the microstructure of ceramic material "Z" revealed
the presence of approximatively 30-35 vol.% of inclusions in the alumina matrix.
7. 31
The X-ray diffractometry confirmed the presence of TiC and TiN, but it was
not possible to ascertain the presence of zirconia with this analytical method,
because probably its quantity is lower than 5 vol.%. After the turning tests the
surface fractures covered by a metallic layer are evident, but it was not possible
find evidence of cracks in the crater bottoms.
F
= ~x~
LJ
4
10 =
k
Kt/Km=0.1
10
Cutttng opood Em/ooo ]
010
m
6J
o
,.s
o
o
t--
10
|illl
~ 1 1 1
I ~ L I I I I
I I k 1 ~ l l
IlIl~l
I I 1 ~
IIIW
Vb=O. 3
10
Cut, ttng opood Em/ooo]
Figure 1. Tool life - cutting speed relationship for feed=0.28 mm/rev.
r~
°10
m
t_l
I
o
o
I--
10
3
k',
~ o
z
K t/Km=O. 1
10
CuLttng opood rm/ooo]
r-~
=°10=
m
o
o
o
b-
10 =
G
~'%
z
Vb=O. 3
10
Cutt, tng epeod Em/oeo ]
Figure 2. Tool life - cutting speed relationship for feed=0.224 mm/rev.
In Tab. 3a and 3b some relevant statistics related to the fitted curves are also
reported in the last two columns. The first one represents the squared
correlation coefficient; as it can be noted these values are highest in both
criteria, assuring that the two variables (cutting speed, life) are linked very
8. 32
Figure 3. Macrocracks in the insert
"F" filled by steel, after cutting at 7.8
m/sec for 540 sec using a feed rate of
0.28 mm/rev
Figure 4. Macrocracks in the insert
"F" of Fig. 3 with iron distribution.
Figure 5. Flank wear in insert "F",
after cutting at 11 m/sec for 330 sec
using a feed rate of 0.224 mm/rev
Figure 6. Pull out of the WC
particles in the insert "C", after
cutting at 7.8 m/sec for 30 sec using
a feed rate of 0.28 mm/rev
9. 33
strictly. The second one is a F-test which computes the divergency from linearity
in respect of the internal variability measured on the replications obtained with
same cutting conditions. Such F-test value is followed by the associated
significance level. As it can be seen, for the crater depth criterion the linearity of
the relationship must be questionable, in fact the reached significance levels are
below 5% for five curves on six. On the other hand, for the flank wear criterion,
only one fitted relation show a significative divergency from linearity (F=13.73,
P=0.01). In base of this, the measures of flank wear criterion give a best fitness
to the Taylor's curves for these cersmlc materials (G, F, Z).
On the other hand the measurement of flank wear evaluation, Fig. 5, on the
"F", "G" and "Z" ceramic materials is easy, exact quick and repeatable. For these
reasons for this ceramic materials, the flank wear must be measured to evaluate
wear.
As seen from Tab. 3a and 3b the tool life and Taylor's constants of ceramic
materials "C", "S", "B" and "W" are not reported. This is due to their poor wear
resistance. The average tool life of these ceramic materials are reported in
Tab.4.
The sintered carbide "C", WC - Co, exhibits a relatively high wear rate,
Tab.4. This behavior can be attributed to the high temperature attained during
the tests at high speeds. Under these conditions the binder phase (a Co based
alloy) is softened and the WC particles can be easily pulled out by the
mechanical action of the tuning metallic piece. In Fig. 6 is presented the view of
the inner edge of the crater: the pull out of the tungsten carbide particles and
the deformation of the metallic phase are evident. Also we can observe, from
Tab. 4, that only for sintered carbide "C" the tool life for each speed and feed,
with flank wear land criterion Vb=0.3, is three or four times that of analogous
tool life with crater depth criterion KtlKm = 0.1. This means that this material
has poor flank wear for the speeds, feeds, depth of cut and tool geometry
employed.
In the ceramic material "S" the wear rate is very high and the craters are
large and deep, Table 4. This behavior is due to the chemical reaction between
the steel and the binder phase which is present in the silicon nitride materials.
In Fig. 7 is shown the crater bottom after a chemical etching which has removed
the surface layer. It is evident that the metal (the grey and smooth phase) has
reacted with the ceramic material and has permeated in the SisN4. It was also
observed that, under the same test conditions, the width of the crater in the "C"
and in the "S" cutting tools is approximately the same, whereas the depth in the
SisN4 insert is higher. This behavior can be explained considering that the
chemical wear in the silicon nitride materials is preeminent.
The cutting tool "B" consist of a cutting edge, joined by brazing to a sintered
carbide holder. The cutting edge is based on cubic boron nitride (CBN) particles
and exhibits a poor wear resistance, Table 4 [17]. As in the case of the "C"
material, the performances of this tool are related to the high temperature
behavior of the binder phases.
10. 34
Figure 7. Crater bottom of the insert
"S", after cutting at 7.8 m/sec for 10
sec using a feed rate of 0.28 mm/rev.
Deep penetration of the steel in
Si3N4 are evident.
Figure 8. Crater wear of the insert
"W", after cutting at 7.8 m/sec for
300 sec using a feed rate of 0.28
mm/rev.
Figure 9. Insert "W" of Fig. 8. The
holes previously occupied by the
whiskers are evident.
Figure 10. Spherical particles
deposited on the surface of the insert
"W" of Fig. 8
11. 35
Despite of the room temperature high toughness of the silicon carbide
whiskers the insert "W" exhibits a relatively high wear rate, Table 4. This
behavior can be explained examining the altered microstructure of the crater
borders. The ceramic surface under the deposited metallic layer is completely
free from the SiC whiskers and holes are also evident where the whiskers were
previously set, Fig. 9. The pull out of the reinforcements is essentially due to a
chemical reaction between the steel and SiC with formation of silicides and
eutectics [18]. The presence of many particles with a spherical shape is the
indication of the liquid formation during the cutting tests, Fig. 10. No cracks
were found in this insert and its behavior can be explained considering its high
toughness and its high thermal conductivity, Table 2. On the basis of the above
mentioned observations it is possible infer that in this cutting tool the chemical
wear is predominant on the mechanical.
4. CONCLUSION
On cutting steel, with speeds from 5ndsec to 11ndsec and feeds from
0.2mm/rev to 0.3mm/rev with ceramic materials, previous mentioned, we can
conclude that:
-no ceramic materials tested have sufficient performance at llrrgsec;
-oxide based alumina, alumina in submicron grain and the mixed based
alumina, have shown the better wear resistance: the latter has shown a wear
resistance that is a little lower than the previous materials;
-the highest wear rate was exhibited by the silicon nitride cutting tools "S",
this behavior is due essentially to the chemical reactions between the steel and
the binder phase;
-the WC-TiC-Co cutting tools "C", showed poor performances because of the
heavy pull out of the tungsten carbide particles. In this case the wear can be
essentially imputed to the plastic behavior of the metallic matrix at high
temperatures;
-better performances exhibited the ceramic materials "F" and "G", despite
the chemical stability of alumina, evidence of reactions between the steel chips
and the ceramic material were observed; the presence of cracks filled of metal
and fracture surfaces with a high iron concentration suggest that the wear
mechanism is of mixed type: mechanical and chemical;
-the wear resistance of the insert "Z" is comparable with that of the two
above mentioned alumina based tools;
-SEM examination of the cutting tool "W" showed the presence of an
important chemical reaction between the steel and silicon carbide whiskers;
-the presence of a binder, also influences the performances of the "B" cutting
tool, which exhibits a poor wear resistance, despite the hardness of the CBN
particles.
12. 36
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