Milling Insert Research Articles

Research on Adhesion Failure of Milling Insert and Mechanical-Thermal Coupled Field in Milling of Difficult-to-Cut Materials

The measuring temperature and force experiments of cutting heat-resistance steel (3Cr-1Mo-1/4V alloy and 1Cr18Ni9 alloy) by plane milling insert and milling insert with complex groove that invented by ourselves has been done, meanwhile, the falling process of sticking-welding chip when milling insert cut-in and cut-out has been observed by high-speed photograph. Mechanical-thermal coupled field has been analyzed using ANSYS, and equivalent complex stress of the coupled field is larger than the stress of single field distinctly, it shows that they have a relation of direct proportion. The results of test and analysis show that the main reasons of adhesion failure are heat that produced in cutting process and the change of temperature grads during cut-in or cut-out and alternate tension stress and stress impact during cut-in or cut-out., which provides technical support and experimental data for the groove's optimization and reconstruction of milling insert with 3D complex groove.

Pulsed DC magnetron sputtered tantalum nitride hard coatings for tribological applications

Transition metal nitride coatings are used in electronics industry as a diffusion barrier coating. In the present study, tantalum nitride thin films were coated at room temperature (300 K) on various substrates, such as cemented carbide milling inserts, glass and stainless steel, using pulsed DC magnetron sputtering technique. Optical emission spectroscopy (OES) was employed to analyze the sputtering plasma to understand the reaction kinetics of tantalum nitride formation. The properties of the films were evaluated by various techniques, including X-ray diffraction (XRD), scratch adhesion test, ball-and-crater method and atomic force microscopy (AFM). The deposition rate was found to increase with an increase in sputtering power. The coatings were amorphous at low sputtering power, and showed development of crystalline structure, with (111) orientation. The initial results show that the film structure and adhesion needs to be improved further for tribological applications.

Study on the Adhering Disrepair and Groove Optimization of Cutting Tools for Difficult-to-Machine Materials

In the course of the milling experiments with the difficult-to-machine material 3Cr-1Mo-1/4V steel, we have found the substance of the adhering disrepair. In addition, we forecast the predominant capability of the waved-edge milling insert with complex 3-D grooves by the synthetically blurry judgement. Eventually, we give the mathematical model between the milling temperature and the maximal adhering disrepair depth of the rake face, and analyze the rule that the milling temperature affects the adhering disrepair. What’s more, we testify the predominant capability of the waved-edge milling insert.

Influence of cutting edge radius on the wear resistance of PM-HSS milling inserts

The wear behaviour of PM-HSS milling inserts is investigated experimentally. Cutting inserts with different cutting edge radii tested in industrial conditions were examined. The radii have been obtained either by micro-sandblasting or by honing. The initiation and progress of the tool wear was analysed with scanning electron microscopy (SEM) of the cutting edges. The experimental results exhibit quantitatively the effect of tool radius on the performance of milling inserts. A radius on the cutting edge prevents fast and unpredictable wear. Moreover, the existence of an optimum value of the radius has been revealed experimentally. In parallel, 2D finite element cutting simulations based on Lagrangian thermo-viscoplastic formulation are used to analyse the tool-stress distributions within the tool coating and substrate. The results obtained from this study provide a fundamental understanding of the cutting mechanics for the coated tool used and can assist in the optimisation of tool edge design. Particularly, the results obtained from the simulations have confirmed that there exists an optimum cutting edge radius that minimizes tool stresses, especially within the coating layer, which seems to be a key factor in the case of milling in dry high speed conditions.

Study on Groove Optimization Technology Based on the Power Spectrum Analysis

Based on the milling force testing system, we have experimented with the waved-edge milling insert and the great milling insert developed by Harbin University of Science and Technology, the American Metal milling insert, the ISCAR hackle milling insert and the flat milling insert, and then compare the insert milling capability of various grooves milling inserts. We have discussed the dynamic milling force under the incontinuous cutting condition, especially the characteristic of time and frequency. Based on the power spectrum analysis of the five types of milling inserts, we have found that the insert whose groove is formed from the curve or curly plane of the period function has an advantage on minishing the milling force and resisting to vibration. The right insert geometry parameters have great effect on improving the cutting capability. By the power spectrum analysis, we found that the complex 3-D grooves milling insert is superior to the flat milling insert on minishing milling force and vibration. The analysis result proves that using power spectrum analysis in groove optimization is viable.

A Rise in Temperature by Moving Planar Sources of Heat on the Rake Face for the Waved-Edge Milling Inserts

A Rise in Temperature by Moving Planar Sources of Heat on the Rake Face for the Waved-Edge Milling Inserts

Internet-based optimization and choice of insert grooves for face-milling

Milling inserts with three-dimensional complex grooves are optimized and chosen via the Internet in this paper. The face-milling process is studied, with mathematics models of cutting force for different shapes of cutting edges established, cutting forces predicted and stress fields of different insert grooves analyzed by FEM. According to the predicted results. The most suitable insert grooves for particular machining conditions are then optimized and chosen. The complex groove optimization and choice are based on a client/server model, with the client and server being on different machines across the Internet. Communication between the client and the server uses the TCP/IP. The result of optimization and choice will be sent to the user via the Internet. Manufacturers all over the world can obtain the desired insert groove without paying for expensive experiments. Thus, the cost and lead time of products are reduced.

Development of an expert system for turning and rotating tool selection in a dynamic environment

In metal cutting, the selection of a proper cutting tool plays a significant role in achieving consistent quality and in controlling the overall cost of manufacturing. However, searching for a proper tool/insert — job combination calls for a huge amount of data and an extensive knowledge base. In the present paper, the manual effort of searching is substituted for by E xtool, an expert system, which automatically selects the turning tool/insert or milling insert, the material and the geometry, based on the requirements of users. Trade-off among the different cutting parameters of the operation is also performed by the developed system as and when necessary. The application of this developed expert system is highlighted by executing some practical problems. This research effort can be of great use in manufacturing industries for optimum use of their resources.

MULTIMILLING-INSERT WEAR ASSESSMENT USING NON-LINEAR VIRTUAL SENSOR, TIME-FREQUENCY DISTRIBUTION AND NEURAL NETWORKS

The objective of this study is to establish a signal processing methodology that can infer the state of milling insert wear from translational vibration measured on the spindle housing of a milling machine. First, the tool wear signature in a translational vibration is accentuated by mapping the translational vibration into a torsional vibration using a previously identified non-linear relationship between the two, i.e. a virtual sensor. Second, a time-frequency distribution, i.e. a Choi–Williams distribution, is calculated from the torsional vibration. Third, scattering matrices and orthogonalisation are employed to identify the time–frequency components that are best correlated to the state of wear. Fourth, a neural network is trained to estimate the extent of wear from these critical time frequency components. The combination of the virtual sensor, time–frequency analysis and neural network is then validated with data obtained from real cutting tests.

Assessment of machining features for tool condition monitoring in face milling using an artificial neural network

Because of a wide scatter in the tool lives of face milling inserts and limitations of conventional methods for predicting the same, artificial neural systems have become advantageous for their ability to learn input-output mappings. Process parameters coupled with machining responses and experimental observations provide a basis for monitoring the tool wear in face milling. Chip characteristics such as shape and colour together with features of force and vibration are potential candidates for wear prediction in the field of tool condition monitoring.

Process simulation using finite element method — prediction of cutting forces, tool stresses and temperatures in high-speed flat end milling

End milling of die/mold steels is a highly demanding operation because of the temperatures and stresses generated on the cutting tool due to high workpiece hardness. Modeling and simulation of cutting processes have the potential for improving cutting tool designs and selecting optimum conditions, especially in advanced applications such as high-speed milling. The main objective of this study was to develop a methodology for simulating the cutting process in flat end milling operation and predicting chip flow, cutting forces, tool stresses and temperatures using finite element analysis (FEA). As an application, machining of P-20 mold steel at 30 HRC hardness using uncoated carbide tooling was investigated. Using the commercially available software DEFORM-2D™, previously developed flow stress data of the workpiece material and friction at the chip–tool contact at high deformation rates and temperatures were used. A modular representation of undeformed chip geometry was used by utilizing plane strain and axisymmetric workpiece deformation models in order to predict chip formation at the primary and secondary cutting edges of the flat end milling insert. Dry machining experiments for slot milling were conducted using single insert flat end mills with a straight cutting edge (i.e. null helix angle). Comparisons of predicted cutting forces with the measured forces showed reasonable agreement and indicate that the tool stresses and temperatures are also predicted with acceptable accuracy. The highest tool temperatures were predicted at the primary cutting edge of the flat end mill insert regardless of cutting conditions. These temperatures increase wear development at the primary cutting edge. However, the highest tool stresses were predicted at the secondary (around corner radius) cutting edge.

Tool life and wear mechanism of uncoated and coated milling inserts

A systematic study was conducted for face milling inserts cutting 4140 preheat treated steel. The flank wear of uncoated C5 carbide insert, as well as TiN, TiAlN, and ZrN coated inserts was evaluated and ranked. Tool life was expressed as the function of cutting speed and feed. This information is useful for production optimization. Wear mechanisms of attrition, abrasion, mechanical fatigue, and thermal fracture were identified and were represented by wear maps. The TiN and TiAlN coatings provided significant improvement in tool life. The ZrN coated inserts performed about as well as the uncoated C5 carbide inserts.

Application of PIM for Manufacturing WC-Co Milling Inserts.

The objective of this study is to examine the feasibility of manufacturing WC-Co milling insert by PIM process. WC-Co is used in a wide variety of cutting tools due to its high hardness, stiffness, compressive strength and wear resistance properties. WC-Co parts for a high stress application were conventionally produced by the press and sinter method, which were limited to 2 dimensional shapes. Manufacturing WC-Co parts for a high stress application by PIM implies that tool efficiency can be highly improved due to increased freedom in design.P30 grade WC powder (WC-Co-TiC-TaC system) was mixed with RIST-5B 133 binder and injection molded into milling inserts (Taegu Tech. Model WCMX 06T308). The mean particle size of the powder was about 0.8μm. Injection molded specimens were debinded by solvent extraction and thermal degradation method at various conditions. The specimens were sintered at 1400°C for 1 hr in vacuum. Carbon content, weight loss, dimensional change, and macro defects of the specimen were carefully monitored at each stage of the PIM process.PIMed WC-Co milling inserts reached 100% full density after sintering. Its mechanical properties and micro-structures was comparable with the press and sintered milling insert. Carbon content of the sintered WC-Co insert was mainly determined by the atmosphere of thermal debinding. By controlling powder loading and injection molding condition, dimensional accuracy could be obtained within 0.4%. We confirm that PIM can not only be an alternative manufacturing method for WC-Co parts economically but also provide a design freedom for more efficient cutting tools.

The Texture and Macrostress Measurements for Cutting Tool PVD Coatings

The details of X-ray techniques such as fluorescence thickness measurements, residual macrostress and texture determination for mono- and multilayers coatings of HSS and CC cutting tools are considered. The features of macrostresses measurement concern with thin high textured coatings are considered. The macrostress phenomenon concern with difference of thermal extension coefficient (TEC) of coating and substrate, deposition parameters and layer sequence in the multilayer coatings are discussed. The macrostress data concern with cutting performance of coated milling inserts are considered. High compressive residual stresses and pronounced {111} texture for HSS and weak compressive or tensile stresses for CC it is revealed for monolayer TiN coatings. The multilayer coatings TiN/Ti/TiN... are designed to minimize the stress level. The specific texture of alternating layers like Ti, TiB 2 , Al 2 O 3 , AIN and SiC, which have the TEC anisotropy (α c ¬= α a ), can be used for governing of macrostress. Ultra-high macrostresses up to 16000 MPa have been revealed for Zr-N, Zr-N-C, Zr-Nb-N and Zr-Nb-N-C coatings on HSS. The texture of ZrN phase for the polycomponent coating systems have more strong technology sensitivity in comparison with two-component coatings.

Comparison of the steel-milling performance of carbide inserts with MTCVD and PVD TiCN coatings

This study is a comparison of the performance of PVD-TiN-, PVD-TiCN-, and MTCVD-TiCN-coated milling inserts. It is shown that metal-cutting conditions and insert geometry dictate the optimum performance for each type of coating. The importance of compressive residual stress in PVD coatings in delaying the initiation of damaging cracks at the edge is evident in these results. Conditions in which thermal shock is not severe, such as dry milling or lower-speed wet milling and the use of sharp cutting edges, are shown to maximize the performance of the PVD-TiCN-coated tool. On the other hand, the MTCVD coating necessitates a strong cutting edge geometry on a tough substrate to obtain good performance, in wet milling. Practical productivity implications, including environmental concerns, are considered.

Factors leading to improved thermal cracking resistance in carbide milling inserts

Factors leading to improved thermal cracking resistance in carbide milling inserts

Effect of variation in edge geometry on wear and life of coated carbide face milling inserts

Brittle tools such as carbides and ceramics usually fail by wear and often by brittle fracture. Wear is a systematic process and predictable but, because brittle fracture is random and catastrophic in nature, it is very detrimental in all respects, particularly for machining expensive jobs in sophisticated machine tools. The problem of such premature tool failure becomes more acute in intermittent cutting such as face milling which is characterized by both thermal and mechanical shock loading. It has been reported earlier that proper edge bevelling retards tool failure, particularly by fracturing, mainly through edge strengthening, controlled contact cutting and better heat dissipation. The present authors have experimentally studied the effects of bevelling the major cutting edge with varying land geometry on the magnitude and pattern of chipping, fracturing and wear of coated carbide face milling inserts under high speed-feed machining of low carbon steel. Based on the experimental results a mathematical model has also been developed depicting the role of the major geometrical and process parameters on the tool life. It has been observed that the land geometry and edge radius play significant roles in the wear pattern and life of such milling inserts. Scope exists to optimize the geometry of the cutting edges for the best performance of such tools for different levels of cutting speed and feed.

Relationship between carbon chemistry and thermal cracking resistance in carbide milling inserts

Determination of thermal crack resistance for a tungsten carbide composition with varying carbon concentrations is made using a milling test and laboratory analysis. It is shown that the most thermal-crack-resistant material had the highest compressive residual stress. Residual stress also appeared to be dependent upon the material's carbon stoichiometry and binder phase chemistry.