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Learn about cutting tool wear and life | thecnc2020
Tool wear and tool life
This article deals with the wear and tear of cutting tools. Let's learn about" Wear phenomenon; The nature of wear; Mechanism of wear phenomenon, wear measurement method.
1. Abrasion phenomenon
During chip cutting, the sliding motion and friction on the tool front face of the working part of the moving part are in contact with the back of the tool under conditions of high pressure, high temperature, and intense and continuous friction causes knife wear phenomenon.
2. Abrasive nature
It is a very complex phenomenon, occurring according to the physico-mechanical phenomena at the contact surfaces between the chip, the workpiece and the tool. Continuous contact and friction between the chip and the tool or part surface cause corrosive friction.
3. Mechanism of wear phenomenon
- Abrasion due to scratches or abrasive particles
- Abrasion due to diffusion
- Oxidation wear
- Fatigue wear
4. Types of wear and its influence on the quality of workpieces as well as tooling
a) Types of wear:
- Abrasion along the back, front
- Abrasive Crater
- Abrasive Crater
- Sharpening the cutting edge
- Sharpening the tip of the knife
b) Effect of wear on tool life:
Reduces tool life quickly
May cause destruction of the tool's cutting edge
Reduce the surface gloss of the part when machining
Increase production cost
Method of measuring wear
There are many methods for measuring wear and calculating durability, but we can divide them into two main types: direct measurement and indirect measurement (online and offline).
- Direct measurement is when we finish machining, take out the tool and take the gauge directly to see how the tool wear is. (offline measurement) this way is not very feasible because there are too many measurement errors encountered when progressing. measurement should be rarely used
- Indirect measurement is that we use modern measuring tools to measure wear even when the tool is being processed, we can still measure it without having to turn off the machine to take out the cutting tool, reducing errors. number when measuring should be widely applied with many different types of measurement with high accuracy.
- The current trend in the world is that we use measuring instruments with a laser beam with a definite wavelength that shines on the tool to be measured and captures and simulates the wear surface of the cutting tool transferred to the machine. Calculates with wear parameters and can give tool wear and life (online measurement).
“ CUTTING FORCE MODEL FOR TOOL WEAR ESTIMATION” - TSU-REN KO, Research Assistant YORAM KOREN, Professor Department of Mechanical Engineering and Applied Mechanics The University of Michigan Ann Arbor, MI 48109
Very detailed presentation of the calculation as well as the measuring tool for wear in addition to other advanced measures of wear are clearly written in the following documents:
Using wear sensor
Monitoring the tool wear, surface roughness and chip formation occurrences using multiple sensors in turning
While the machine is in operation (roll milling) wear can still be measured. On-line tool wear measurement for ball-end milling cutter based on machine vision.
Wear monitoring through smart chips
MONITORING TOOL WEAR THROUGH FORCE MEASUREMENT
New wear monitoring and measuring tool with complex chip and laser system:
Online tool wear prediction system in the turning process using an adaptive neuro-fuzzy inference system
An optoelectronic method for on-site tool monitoring using real-time vision technology with laser application
OPTICAL FLANK WEAR MONITORING OF CUTTING TOOLS BY IMAGE PROCESSING
Measures against wear
· Calculate reasonable cutting parameters
· Use coolant to reduce friction, reduce heat and wear to increase tool life.
· Making cutting tools with alloys or good wear-resistant materials such as carbides (Tungsten Carbide, Titanium Carbide...) synthetic ceramic.
· Spray coating on the tool surface with compound films (TiAlN, TiN, PVD, TiCN, AlTiN, CrN, Diamond…) to increase hardness and resist oxidation and abrasion.
· Fabrication of chip exit grooves on the cutting tool that are sprayed with chemical films to increase chip escape, reduce friction and reduce oxidation, increase tool rigidity without affecting cutting speed .....
· Modifies the abrasive particles to create a coating with a longer life and higher cutting ability… (Al2O3 crystal transformation => Duratomic inserts)….
Researches in the world on wear and current remedial directions:
Determination of wear and durability parameters by on-line measurement method by laser beams, electronic chips, infrared right in the machining process with low cost:
a) “Online tool wear prediction system in the turning process using an adaptive neuro-fuzzy inference system”:
- Main content:
“Abrasion is a detrimental factor affecting the quality of the machined part. Having accurate tool wear prediction is important for the machining industry to maintain machined surface quality and thus can reduce inspection costs and increase productivity. Online and real-time measurement of the predictive engine is possible due to the development of sensor technology. Recently, different sensors and methods have been proposed for the development of instrument monitoring systems. In this study, an online monitoring system tool was proposed using a strain gauge type sensor due to its simplicity and low cost. A model , based on the adaptive fuzzy network based inference system ( ANFIS ) , and a new statistical signal analysis method , the I-kaz method , are used to predict wear in a process labor . To develop the ANFIS model, cutting speed, depth of cut, corrosion rate and I-kaz from the signals of each rotation were taken as input and the value for the cutting tool is a model output. It can be seen that the correct predictions of the correlation of the coefficients and the mean errors are in the range of 0.989-0.995 and 2.30-5.08% respectively for the developed model. An efficient and low-cost model proposal that can be used in the machining industry for online prediction of abrasive cutting tools is developed, but the accuracy of the model depends on experimental data. test and test.”
b) “Tool Probe for Measuring Dimensional Wear and X- ordinate of turning edge”
- Main content:
An original method of direct measurement of wear at the tip of the cutting edge, automatically performed on an NC lathe by a probe, which simultaneously allows to determine the simultaneous X of the cutting edges . In the original solution, this measurement, patented by one of the authors, is made using a special probe with two touch-triggered sensors or one touch-triggered sensor and displacement sensor. The improved transducer has only one displacement sensor. These new solutions not only simply probe but also make wear measurement tools more accurate.
+ Measure surface parameters by 3D microscope
“Surface topographical evaluation of coated cutting tools with different coating Technologies
- Main content:
This study provides the detailed study of the method of characterization of surface geometry with an evaluation process using both stylus profilometer (SP) as contact measurement system and microscope. 3D digital (DM) and a type of scanning laser confocal microscope (SCLM) as non-contact measurement system. The purpose of this application is to learn the difference between cutting tools with and without coating before running the machine. This study considers the initial conditions when measuring the surface roughness of cutting tools. Results from surface roughness measurements determine with certainty that these technologies improve surface coating quality and tool life. Errors between the measured values from SP and SCLM were calculated , in terms of sampling location and instrument type , respectively . Regarding the Ra parameter , for the coated cutting sample tool 1 ( 1CCTS ) , the root mean square error ( RMSE ) is 0.023 lm and 0.030 lm for SP and SCLM , respectively . In terms of parameter Ra, for sample uncoated cutting tool 1 ( 1UCTS ) , the mean square error root ( RMSE ) is 0.053 lm and 0.070 lm for SP and SCLM , respectively .
Infrared cutting and wear measurement
“Extended infrared thermography applied to orthogonal cutting Mechanical and thermal aspects”
- Main content:
Knowledge of temperature is essential to understand and simulate the phenomena associated with metal cutting. An overall measurement can only provide a clue of heat generation during the process; However, a deep understanding of the thermal aspects of shear requires an understanding of the temperature field. This article focuses on infrared temperature recording applied to orthogonal shear and extends an initial experimental setup. A lot of information is measured directly or after processing. These mainly focus on the geometric or thermal mechanical aspects of chip formation, i.e. toolechip contact length, chip thickness, main cutting angle, heat flux generated in the shear or friction zone, and tool echip interface temperature distribution . This article proposes an experimental set-up and post-operative technique that allows to provide a lot of basic and initial information about metal cutting process. Several comparisons between data collected and pre-test or follow-up retical results were performed.
Build low-cost and easy-to-use online wear monitoring systems:
Monitoring online cutting tool wear using low-cost technique and user-friendly GUI
- Main content: Cutting tool wear is known to affect tool life , surface quality and production time . Because this is an online monitoring and measuring instrument system has been developed, using a low cost sensor. The system can detect and analyze the signal related to the tool's base deviation from the cutting force, and the corresponding estimate of is displayed on the computer screen. New statistical analysis is used to identify and describe changes in the signal from the sensor. A two-channel strain gauge is mounted in the center of the tool to measure deflections in both tangent and feed directions. The signal is transmitted to the signal conditioning equipment, then to data acquisition, and finally to the computer system. MATLAB software is used as the foundation software to develop a graphical user - friendly interface (GUI) for online monitoring. The results show that this developed online monitoring system, using strain gauge signals, is an effective method to detect the evolution of the blade width during machining. It is an effective and low-cost method that can be used in the real machining industry to predict wear levels in tools.
Gradually replace coolant completely in machining to reduce costs, increase tool life and limit corrosion (dry and semi-dry machining).
Document:
a) Dry-Machining with TITEX PLUS-Tools
- Main content:
Refrigerants are often used in the machining process. They reduce wear and dissipate heat from workpieces and machines, aid in the removal of chips and release cutting residue belonging to workpieces, tools and equipment. All in all is an important prerequisite for a smooth fabrication process. Increased use of coolants in recent years has caused a significant increase in procurement, maintenance and disposal costs. The suitability of the coolant with the environment and the potential health risks to the machine operator created by the latter has increasingly become the subject of criticism. The disposal of the used coolant is not entirely eco-sound and also causes an increase in costs.
b) A comprehensive tool-wear/tool-life performance model in the evaluation of (near dry machining) for sustainable manufacturing
- Main content: Traditionally, metal working fluids (MWFs) have been the way to improve work efficiency despite the adverse effects on ecology and health. A new sustainable process that has reduced the use and application of MWFs is NDM (near dry machining). Although there is controversy about the effectiveness of NDM, the consensus is that the lack of a science-based model precludes its widespread use. This paper presents a new method for predicting tool-wear/tool-life performance in NDM by extending a Taylor speed dry machining equation based on . Testing and validation work of the models was performed in an automotive production environment in the machining of the steel wheel rims. Machining experiments and validation of the new equation revealed that tool wear could be predicted within 10% when the impact of NDM was statistically different than that of dry machining. Measurement of tool wear in validation of the model shows that NDM can improve tool-wear/tool-life more than four times compared to dry machining which highlights the need for sustainable development of the model to fit consistent with current practice
Research and manufacture cutting tools with super hard materials to limit wear, increase durability and replace tools grinding operations after machining
Manufacture of cutting tools that can process parts with difficult-to-machine soft metal materials with high precision and gloss (designing additional grooves and surface coating of grooves and cutting tools). ).
“Abrasive slurry jet micro-machining of holes in brittle and ductile Materials” - K. Kowsari, H. Nouraeia, D.F. James, J.K. Spelt, M. Papini
- Main content: This article investigates the influence of elasticity and viscosity, induced by a dilute solution of high molecular weight polymer, on the shape, depth, and diameter of micro-boreholes in borosilicate glass and in sheet 6061 -T6 aluminum alloy , 110 copper , and 316 stainless steel use low pressure suspension abrasive micromachining ( ASJM ) . Holes are machined using a micro-machined suspension injection machine with a 1% aqueous solution weighing 10 m of Al2 O3 particles. 180 m sapphire hole manufactured by micromachined 140 m diameter with pressures of 4 and 7 MPa. When the microprocessor contained 50 wppm of 8 million molecular weight polyethylene oxide (PEO), the blind holes in the glass were about 20% narrower and 30% shallower than those drilled without the polymer, using same abrasive concentration and pressure. The addition of the PEO resulted in the cross-sectional profile hole which had a sharper edge on the glass surface and was more V-shaped compared to the U-shape of the hole produced without PEO. Hole symmetry in the glass is maintained over a depth of about 80-900 m by ensuring that the micromachines have been aligned perpendicular to the 0.2 ◦ ring. The changes in shape and size were brought about by the normal problems created by the polymer. This soluble polymer-containing micromachine was observed to oscillate sideways and non-periodically, with an amplitude of 20 m. For the first time, ASJM is symmetrical through holes that have been drilled in a 3mm thick borosilicate glass sheet without chipping around the exit edges. The depth of the symmetrical blind hole in metals is limited to approximately 150 m for micromachines with and without PEO. At greater depths, the holes become very asymmetrical, eroding in a particular direction to create a subsurface slit. Asymmetry appears to be caused by the extreme sensitivity of flexible materials to micromachined bonding. This sensitization also caused holes in the metal to be less circular, when PEO was included, apparently caused by random micromachining fluctuations caused by the polymer. Under the same conditions, the hole depth increases in the order: borosilicate > 6061 -T6 aluminum > 110 copper > 316 stainless steel. The edges of holes in the glass can be made sharper through a glass or epoxy layer specimen.
The change in hardness and tool life when the tool surface is sprayed
“Microstructure of TiAlN and CrAlN coatings and cutting performance of coated silicon nitride inserts in cast iron turning”- Ying Long, Junjie Zeng, Donghai Yu, Shanghua Wu
- Main content:
Ti0.5Al0.5N and Cr0.3Al0.7N paints are produced by ca-arc evaporation (CAE) on silicon nitride cutting inserts. The microstructure and compositional phase of the coating were investigated by SEM and XRD, respectively. The hardness of the coating is evaluated by applying micro-hardness test. Rotational testing was performed on both coated and gray coated cast iron rotating cast irons in a dry environment. Wear behavior and shear performance of coated and coated inserts have been studied. The results show that Ti0.5Al0.5N coating has higher hardness than Cr0.3Al0.7N coating due to its smaller particle size. The cutting performance of silicon nitride inserts has been improved with the inclusion of Ti0.5Al0.5N and Cr0.3Al0.7N coated with at least 2 times of the cutting life. No cracking occurred after shear tests for both Ti0.5Al0.5N and Cr0.3Al0.7N overlays. Ti0.5Al0.5N coating performs better cutting efficiency and tool life than Cr0.3Al0.7N coating. The dominant wear mechanism of Ti0.5Al0.5N and Cr0.3Al0.7N inserts has been abraded with grooves in the wear surface die.
Ø Making special “cutting inserts”
- Pictures of special inserts
+ Inserts are specially used for turning
+ Inserts are specially used for milling.
+ Special Inserts for slotting.
+ Special Inserts for boring, boring machining
- Tài liệu:
“Influence of grinding parameters on the quality of high content PCBN cutting inserts”- B. Denkena, J. Köhler, C.E.H. Ventura
- Main content:
Grinding face plunge is commonly used to complete PCBN cutting inserts. To achieve the full design process, an investigation of the influence of grinding parameters on the high content quality of PCBN inserts was carried out in this work. For this, inserts are ground with different grinding wheels (including a variation of grain size and alignment), input parameters, surface finish, and cutting speed and chipped edges and faceted blades. roughness is measured. It was found that the reduction of the abrasive grain size as well as the increase of the variable inlet ratio resulted in an improvement of the insert edge and surface quality. Furthermore, a variation of the input and cut speeds has only a small effect on the quality of PCBN inserts.
“Strategies for grinding of chamfers in cutting inserts” C.E.H. Ventura J. Köhler, B. Denkena
Main content: To increase tool life and improve workpiece quality, process cutting with a defined surface cutting need with a prepared cutting edge. Bevels are widely used in many processes, as they can provide edge enhancement without compromising chip flow. To achieve a stable and reliable cutting process, uniform chamfer geometry along the insert and high edge quality are required. For this, the appropriate grinding strategy for chamfer production must be considered. With the aim of gaining knowledge about chamfer manufacturing process, the chamfering strategy is investigated in this paper. The chamfer is ground on a PCBN , ceramic carbide and cementitious blend insert with a vitrified bond diamond grinding wheel . A single grain chip thickness model was used to describe the different grinding process and methods were analyzed in terms of reducing chamfer geometry deviation. It can be seen that the high rotational speed insert increases the chipping edge and the cutting insert has a significant effect on the chamfer geometry deviation.
“Wear behavior and cutting performance of nanostructured hard coatings on cemented carbide cutting tools in hard milling”
- Main content:
The influence of AlTiN/TiN nanolayer and multi-nanocomposite TiAlSiN/TiSiN/TiAlN hard coating on the wear behavior and cutting performance of carbide cutting tools was investigated in face milling of AISI O2 hardened cold steel working tools (58 HRC) under dry conditions. Coating characterization is performed using nanoindentation, which is back-and-forth during machining. Chips formed during cutting are also analyzed. The results show that wear and oxidation have almost no effect on the tool. AlTiN/TiN nanolayer coating gives best adhesion to surfaces, best wear resistance in machining and thus provides longest service life with carbide inserts
Ø Crafting special cooling systems right in the core of the cutting tool
Ø Modification of abrasive particles for machining soft metals with greater precision and surface finish
“Grinding of PCBN cutting inserts” - B. Denkena, J. Köhler, C.E.H. Ventura
- Main content: Inserts into cutting PCBN have been commonly used for the needs of an economically efficient process and resulting in an adequate workpiece surface quality. A proper application of this cutting material requires precise handling of its material. Plunge face grinding is used to complete the insert after sintering. In order to select a suitable grinding tool and process parameters, the properties of the insert into the mill must be taken into account. Therefore, the influence of PCBN particle size and composition on insert edge cutting and surface quality must be investigated. This work aims to give an overview of material removal mechanism, process force and abrasive wear during grinding of various PCBN inserts. It can be seen that the quality of the insertion depends mainly on the material removal mechanism, which in the case of the study is determined by the PCBN particle size.
Ø Increase hardness, reduce wear with carbide tooling materials
“The effects of the multi-layer hard surface coating of carbide inserts on the cutting forces in turning operations
“Modeling flank wear of carbide tool insert in metal cutting”- X. Luo, K. Cheng, R. Holt, X.Liu
- Main content: The influence of AlTiN/TiN nanolayer and TiAlSiN/TiSiN/TiAlN multi-nanocomposite hard coating on the surface and cross-sectional performance of carbide cutting tools were investigated in face milling of AISI O2 hardened cold steel working tools (58 HRC) under dry conditions. Characterization of the coating is performed using nanoindentation, tip inspection, back and forth, wear test. Chips formed during cutting are also analyzed. Results showed that wear and oxidation of weacarbide insertsr were the dominant tool failures. The AlTiN/TiN nanolayer coating gives the best adhesion to surfaces, the best wear resistance in machining and thus provides the longest service life.
High-tech machining monitoring using electronic chips and 3D microscopes
“Novel tool wear monitoring method in ultra-precision raster milling using cutting chips”
- Main content: Tool wear monitoring is a popular research topic in the field of ultra-precision machining. However , there seems to be no research on monitoring wear tools in ultra - precision raster milling ( UPRM ) using chip cutting . In the present study, instrument monitoring was first conducted in UPRM using chip cutters. During the cutting process, the fracture face of the diamond tool is directly imprinted on the surface of the cutting chip as a group of convex convexities. Through examining the sites , the cross-sectional shape of these ridges by a 3D scanning electron microscope , cut the virtual edge of the diamond tool under the built surface layer . A mathematical model was established for virtual advanced prediction with two geometric elements: semicircle and isosceles triangle used to approximate the cross-sectional shape of the convex part. Since the theoretical prediction of edge cutting concurs with one of the tests, the suggested abrasive monitoring method was found to be effective.
Improve accuracy and surface finish when machining soft materials
“Improving machining performance of single-crystal diamond tools irradiated by a focused ion beam”
- Main content: The shape tool is an important factor in determining the shape and precision of the machined area in ultra-precision machining. Using a focused ion beam (FIB) is an effective means to fabricate micro-tool shapes to submicro-scales. However, ionizing radiation causes doping and defects in the tool that reduce tool performance. To apply FIB work on a single crystal diamond tool without sacrificing tool performance, a combination of 500 C heat treatment and aluminum deposition is used to remove the gallium (Ga) ion that causes emitted by ionic radiation. This method is evaluated through experiments showing that Ga ion irradiation causes working materials to adhere to the tool surfaces. This adhesion and resulting rapid tool wear are reduced by heat treatment. The proposed method also improves the reproducibility and wear resistance of the tool so that it is capable of producing a surface quality better or equivalent to that produced by non-irradiated tools, even even longer cutting distances.
Experimental investigation of friction and wear in machining to find the best methods of reducing wear
“Experimental investigation on friction under metal cutting conditions”
- Main content: This article presents an experiment to analyze the friction phenomena inside the tool-chip interface in metal cutting. Therefore, it is designed to obtain experimental data under conditions characterized by high contact temperature, pressure and shear velocity. The experimental methods are derived from an orthogonal shear process, a transformation with a high rate of formation and a friction process using an extremely small rake angle. Such an angle prevents chip formation and results in a smooth resinous flow of metal across the tool surface which generates very high contact temperatures and thus approaches the conditions of needle cutting. type . Investigations were conducted for three billet materials AISI 1045, AISI 4140 and Inconel 718 combined with uncoated WC-6Co reinforced carbide tools. For the literature, empirical analysis shows significant thermal softening in the contact interface caused by frictional heat generation and plastic deformation. To account for the observed phenomenon , a temperature dependent friction model is proposed and evaluated by a finite element model .
- A few other references:
In the book: "Vietnamese metalworking handbook" there is a very detailed article on the production of cutting tools with special grooves that enhance chip removal and limit surface wear by spraying. : http://issuu.com/easterntrademedia/docs/metalworking_guidebook_vietnam
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