Cemented Carbide End Mills Research Articles

ステンレス鋼 SUS304 のエンドミル切削仕上げ面品位に及ぼす工具摩耗の影響

Machined parts of stainless steels as difficult-to-cut materials are widely used in many industries, which are transportation equipment, electrical machinery, automobile and aerospace industry. This study describes that the characteristics of machined surface by end milling-burnishing method for SUS304 austenitic stainless steel on the vertical machining center. It is found that end milling-burnishing process with using conventional cemented carbide end mill tool can improve finished surface quality of austenitic stainless steel without causing a large change of surface roughness. In this case, the influence of tool wear and surface roughness is discussed. As the result of experiments, width of each cutting edge flank wear land in end milling-burnishing method greatly influences the surface roughness. Finished surface of SUS304 has a surface roughness Rz of 0.18 μm.

Highly Accurate Hole Making Technology of Ti6Al4V by Orbital Drilling: Effect of Oil Mist

Ti6Al4V, which is one of difficult-to-cut metals, is widely used in an aircraft structure, parts of a gas turbine and medical equipment, and hole making operation of Ti6Al4V is needed to fasten the parts. When a conventional drilling by twist drill is applied to hole making of Ti6Al4V, it is very difficult to obtain highly accurate hole in diameter, roundness and inlet - outlet edge quality due to a cutting temperature increase caused by a small heat conductivity of Ti6Al4V.Recently, it is well-known that Orbital drilling, which is also called Circular milling, Planetary drilling or Spiral drilling, is superior to conventional drilling for hole making of Ti6Al4V. The author newly developed a hole making machine to enable orbital motion based on Double Eccentric Mechanism so that an endmill driven by one built-in AC motor can rotate clockwise on its own axis at high speed, simultaneously can revolve counter-clockwise on eccentric axis at low speed (Yagishita, 2015).This paper deals with highly accurate hole making technology of Ti6Al4V by employing the machine and a new type cemented carbide endmill having 6 blades. By supplying oil mist from the tip of endmill using a hole through spindle, it is ascertained that cooling by oil mist is strongly effective in order to improve the deviation of hole diameter and roundness, and also edge quality at inlet and outlet of hole.

Study on the carbide tool wear mechanisms in micro milling stair-shape target of LiF crystal

LiF crystal is a kind of soft brittle crystal used as optical functional material. However, severe wear, especially chemical wear for micro cemented carbide end mill which was encountered at the early stage of micro milling process, was firstly found in this paper. Wear regularities and mechanisms were revealed through micro milling experiments and later analysis. Firstly, micro milling of LiF crystal was conducted, and the effect of spindle speed and feed per tooth on the tool wear and surface roughness of the machined workpiece was studied. Then, main wear patterns and their respective mechanisms were analyzed through the SEM micrographs and energy spectrum analysis. Further component analysis and contrast experiments between fused silica and LiF crystal revealed that chemical reactions, especially oxidation reactions should be occurred. Subsequent experiments proved that micro cubic boron nitride (CBN) end mill was suitable for the milling of LiF crystal and the roughness value of the machined surface was still below 30 nm even after a long cutting distance. The paper can provide guidance for tool material election for milling LiF crystal.

湿式条件での超硬エンドミルによるCFRPの切削加工特性に関する研究

湿式条件での超硬エンドミルによるCFRPの切削加工特性に関する研究

Hole Making Machine Based on Double Eccentric Mechanism for CFRP/TiAl6V4 Stacks

Construction parts consisting of 2-layer composite materials made of carbon fiber reinforced plastic (CFRP) laminates and TiAl6V4 still need to be machined, whereby drill holes are frequently manufactured. Recently, it is well-known that Orbital drilling, which is also called Circular milling, Planetary drilling or Spiral drilling, is superior to conventional drilling for hole making of CFRP/TiAl6V4 stacks. The author newly developed hole making machine based on Double Eccentric Mechanism so that a cutting tool driven by one built-in air motor can rotate clockwise on its own axis at high speed, simultaneously can revolve counter-clockwise on eccentric axis at low speed (Yagishita, 2012). The driving mechanism of the machine is entirely different in that respect both high speed rotation and low speed revolution of cutting tool can be created by one built-in air motor from Novator's mechanism (PCT/SE2008/050719) which needs two driving sources.The purpose of this paper is that by replacing a built-in air motor used in the previous hole making machine with a built-in AC motor it is achieved to lighten the weight of the machine and also to be handy by applying electric control device. After that hole making tests are executed to CFRP/TiAl6V4 stacks by using a new type cemented carbide endmill having 6 blades.

Behavior of the magnetic abrasive tool for cutting edge preparation of cemented carbide end mills

Magnetic abrasive processes combine characteristics of grinding and lapping. Due to deformable tool behavior, complex surface shapes and edges can be machined. Therefore, this process is predestined for preparation of drilled cutting tools. High quality finishing results require in depth process expertise. This paper focuses on the behavior of the magnetic abrasive tool taking Magnetfinish® kinematics into account. Main characteristics of the magnetic abrasive tool behavior during finishing end mills of 12 mm diameter are reshaping and in-process densification of magnetic abrasive layer. Consequently, flute surface modifications occur only in the cutting edge surrounding area. Furthermore, in-process displacements of magnetic abrasive cause non-uniform cutting edge rounding. SEM images indicate abrasive motion along the cutting edge as the best method to obtain smooth cutting edge surface.

Microstructure and cutting performance of CrTiAlN coating for high-speed dry milling

Using a closed field unbalanced magnetron sputtering system, the cemented carbide end mills were coated with a CrTiAlN hard coating, which consisted of a Cr adhesive layer, a CrN interlayer and a CrTiAlN top layer. The microstructure and mechanical properties of the coating were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro indentation and scratch test. The cutting performance of the coated end mills were conducted by high-speed dry milling hardened steel (P20, HRC 45). The results indicates that the coating is composed of (Cr, Ti, Al)N columnar grains with nanolayers. The coating exhibits good adhesion to cemented carbide substrate and high microhardness of around 30 GPa. The coated end mills show significant improvement on tool life and much lower cutting force as compared to the uncoated ones. And the related mechanisms were discussed.

초경엔드밀 적용 표면처리 조성별 마모특성 영향 평가

For depth machining in die and mold, Electrical Discharge Machining (EDM) is used generally. To make deep hole and deep shape efficiently, cemented carbide endmill for depth machining is necessary. For this purpose, cemented carbide endmill was designed using design of experiment (DOE). To improve cutting performance, endmill was coated with multilayer surface treatment, TiAlCrSiN and TiAlCrN, for higher wear resistance. In order to evaluate the endmill, Transverse Rupture Strength (TRS) test was tried for investigating the relationship between surface treatment and strength in endmill body. Scratch test was also used for measuring adhesion force of each surface treatment. To evaluate hardness of surface treatment, Atomic Force Microscope (AFM) analysis was carried out. Wear test was executed for characteristics of each surface treatment in high temperature. Consequently, TiAlCrSiN was superior to the TiAlCrN coating in case of high temperature environment such as cutting.

Development of Hole Making Technology of Bi-Layer Composite Materials Consisting of CFRP Laminates and Titanium Alloys

Recently, to construct an airframe 2-layer composite materials consisting of carbon fiber reinforced plastic (CFRP) laminates an TiAl6V4 still need to be machined, whereby drill holes are frequently machined. Special attention has to be paid to the machining quality, which implies hole dimensional accuracy, defect free peripheral zone, edge quality at inlet and outlet of hole and so on. In this research, first by using a high performance CNC machine tool equipped with potent control unit, drilling and circular milling are compared for hole making in CFRP laminates and it is ascertained that circular milling is superior to drilling in defect free peripheral zone and also tool life [. Second, from comparing drilling and circular milling in hole making of 2-layer composite materials consisting of CFRP laminates and TiAl6V4, the superiority of circular milling caused by lower thrust force and lower thermal load than those of drilling has been made clear [. Third, the author has devised a new spindle designed based on double eccentric mechanism so that circular milling can be executed at an airframe assembly site. By using a new handy type apparatus having the spindle driven by air motors, hole making tests were executed to 2-layer composite materials consisting of CFRP laminates and TiAl6V4 with cemented carbide endmill [.

Cutting Edge Preparation of Micro Milling Tools

Micro milling is commonly used industrially for the production of precision components. Premature tool wear is usually the reason for a short tool life of cemented carbide end mills. An approach to improve the tool wear behavior is the defined cutting edge preparation. In this contribution, experimental investigations on the formation of cutting edge geometry during immersed tumbling of micro milling tools are presented and discussed. It could be shown that it is possible to prepare end mills with a diameter D = 1 mm and to generate edge radii of 4.0 μm ≤ rβ ≤ 31.2 μm. Investigations about the correlations between the cutting edge geometry and the tool wear behavior in micro milling operations showed decreased flank and crater wear as a result of an appropriate cutting edge preparation.

Comparison of the Embodied Energy of a Grinding Wheel and an End Mill

In this paper, measurement results of the embodied energy of a corundum grinding wheel and a coated cemented carbide end mill are presented. Both tools are industrial standard regarding geometry and composition. The single process steps and their energy demands for the manufacturing of both tools is analyzed and compared. In addition, based on literature values, their respective wear behavior machining Inconel 718 is compared. Despite a much higher embodied energy of the grinding wheel compared to the end mill, it is shown that the required embodied energy to machine a specific volume of material (J/mm3) is considerably lower for the grinding wheel.

Increasing Tool Life by AlCrTiSiN Film

A cemented carbide end mill was coated with AlCrTiSiN film by cathodic arc physical vapor deposition methods (CAPVD). A performance of AlCrTiSiN film for increasing tool life was evaluated by scratch test, cutting test and oxidation test in comparison with uncoated end mill. From the scratch test, the AlCrTiSiN film was helpful to resist crack and delamination of coating. From the cutting test, the maximum flank wear of AlCrTiSiN film was about two times higher than that of the uncoated end mill resulting in tool life extension. From the oxidation test, the first oxide of AlCrTiSiN film generated after service life was a titanium dioxide (TiO2) at a temperature of 900oC. From all of results, it revealed that the AlCrTiSiN film significantly enhanced the tool life of the cemented carbide end mill.

A Comparative Study of Wear and Oxidation Behaviors of End Mill Coated by PVD Coatings

The objective of this research is to study wear behaviors of TiN, nanolaminated AlCrN and nanocomposite TiAlSiN coated on cemented carbide end mill deposited by cathodic arc physical vapor deposition methods in comparison with uncoated end mill. Wear behaviors were investigated by nanoindentation hardness test, scratch test and cutting test. Oxidation test was also done in air at temperatures of 700°- 900°C in order to evaluate resistance of oxidation. In the nanoindentation hardness and scratch tests, nanocomposite TiAlSiN coating exhibited higher hardness than TiN and nanolaminated AlCrN coatings. The nanolaminated AlCrN coating represented the highest adhesion ability in terms of critical load and the lowest coefficient of friction in comparison with the TiAlSiN and TiN coatings, respectively. The cutting performance, represented in terms of maximum flank wear as a function of cutting length, was found to be highest in the AlCrN coating. Oxides of these coatings, i.e., TiO2 for TiN, TiO2 for TiAlSiN and Cr2O3 for AlCrN, generated at different temperatures of 700°, 800° and 900°C, respectively. From all of results, it is obvious that the AlCrN coating exhibited more excellent wear resistance and oxidation resistance than the uncoated end mill, TiN coating and TiAlSiN coating.

Effect of Machining Parameters on Milled Natural Fiber-Reinforced Plastic Composites

Natural fiber-reinforced composites are recognized as better materials for structural components due to their inherent properties. However, milling these materials presents a number of problems, such as surface delamination and surface roughness (Ra), which appear during the machining process, associated with the characteristics of the material and the cutting parameters. In order to reduce these problems we present this study with the objective of evaluating the cutting parameters (cutting velocity and feed rate) and the influence of the fibers under delamination factor (Fd) and surface roughness (Ra). An experimental plan, based on Taguchi techniques and on the analysis of variance (ANOVA), was established considering milling with prefixed cutting parameters in Natural Fiber-Reinforced Plastic (NFRP) composite materials using cemented carbide end mill. The results of NFRP composite were compared with Glass Fiber-Reinforced Plastic (GFRP) composites. The objective was to establish a model using multiple regression analysis between cutting velocity and feed rate with the delamination factor (Fd) and surface roughness (Ra) of different fiberreinforced laminates.

Evaluation of mechanical properties of Ti(Cr)SiC(O)N coated cemented carbide tools

In order to enhance the life of cemented carbide tools for milling Ti6Al4V alloy, Ti(Cr)SiC(O)N (including TiSiCN, TiSiCON, CrSiCN and CrSiCON) coatings were deposited on flat samples for characterization and K40UF cemented carbide end-mills for milling tests. The adherence strength of the coatings was determined using scratch tests. Wear tests were carried out using a ball-on-disk tribometer with Ti64 balls without lubricant. Dry milling tests of the coated end-mills were carried out on the Ti64 alloy at a 45 m/min cutting speed. The results indicated that the Cr-based coatings (CrSiCN and CrSiCON) have a better adherence strength and toughness than the Ti-based coatings (TiSiCN and TiSiCON). The CrSiCN and CrSiCON coatings had a lower friction coefficient than the TiSiCN and TiSiCON coatings, while the TiSiCN and TiSiCON coatings had a lower wear rate than the CrSiCN and CrSiCON coatings. The milling test results showed that TiSiCN and CrSiCN coated tools had a better cutting performance than TiSiCON and CrSiCON coated ones.

A Time Domain Simulation Approach for Micro Milling Processes

Prediction of Process Machine Interactions (PMI) can be achieved using models for conventional milling processes in the time and frequency domain. However, instabilities such as regenerative chatter can also be observed in micro milling processes using filigree cemented carbide end mills. The dominant chatter frequencies are basically related to the end mills eigenfrequencies. Nevertheless, the dynamic characteristics of the machine tool structure and the work piece must not be neglected. In this paper a comprehensive time domain process model is presented. The machine tool dynamics are considered as non-coupled oscillators based on measured frequency response functions at the tool holder. The end mill is modeled as rotating Euler-Bernoulli beam with variable boundary conditions at the tool clamping. At first, the parameter identification for a geometric cutting force model is described. It contains the cutting edge radius as a time-depended parameter. Thereafter, the modeling and parameter identification of the structural parts are presented. A stability criterion is defined with special regard to the tool deflection at the TCP. Finally, simulation results at different stable and unstable operating points for full immersion cutting are discussed in detail and compared to experimental tests.

Influence of the bias voltage on the structure and mechanical performance of nanoscale multilayer CrAlYN∕CrN physical vapor deposition coatings

The effects of bias voltage on the microstructure and the related tribological properties of CrAlYN∕CrN nanoscale multilayer superlattice coatings were investigated. The coatings were deposited at 450°C substrate temperature by combined high power impulse magnetron sputtering (HIPIMS) and unbalanced magnetron sputtering techniques. The substrates were 304 stainless steel, M2 high speed steel for structural analysis and mechanical testing, as well as cemented carbide substrates end mills for dry high speed milling applications. Substrates were pretreated by HIPIMS etching. The bias voltage Ub was varied between −75 and −150V. The chemical composition was determined by neutral mass spectroscopy. The microstructure was characterized by x-ray diffraction and cross sectional transmission electron microscopy. All coatings had a single phase B1 fcc structure. The chemical composition was not affected by the bias voltage. Local epitaxial or axiotaxial growth attributed to the HIPIMS etching pretreatment was observed on the large surface areas of the substrate crystals. This turned to columnar growth with {110} texture at low bias voltages Ub between −75 and −120V, while at Ub=−150V an equiaxed structure of large crystal sizes developed with {111} texture. At the same time the waviness of the superlattice significantly decreased. An increase in bias voltage resulted in a significant rise in both residual stress levels (from −3.3to−9.5GPa) and plastic hardness (from Hp=34–51GPa), while the coating/substrate adhesion decreased from 61to45N. The friction coefficient increased from 0.43 (at Ub=−75V) to 0.55 (at UB=−120V), while the initial sliding wear rates decreased remarkably (2.6×10−16m3N−1m−1 at UB=−75V to 3.7×10−17m3N−1m−1 at Ub=−150V). The life time of 8mm ball-nosed cemented carbide end mills decreased from 39min at Ub=−75V to 19min when Ub was raised to −150V. These results highlight that the combination of HIPIMS substrate treatment and designed deposition parameters provides good opportunity to tailor coating structures with optimized properties.

CrAlYCN/CrCN nanoscale multilayer PVD coatings deposited by the combined High Power Impulse Magnetron Sputtering/Unbalanced Magnetron Sputtering (HIPIMS/UBM) technology

CrAlYCN/CrCN coating combining high hardness (H p = 36 GPa) and low friction coefficient ( µ = 0.42 against Al 2O 3) has been developed for machining of Si containing Al-alloys. The coating was deposited by the combined High Power Impulse Magnetron Sputtering/Unbalanced Magnetron sputtering, (HIPIMS/UBM) technology. Macroparticle free Cr + ion flux was generated by HIPIMS discharge to sputter clean the substrates prior to the coating deposition. The use of HIPIMS for surface pre treatment resulted in excellent adhesion, scratch test adhesion critical load value of Lc = 55 N on HSS and Lc = 68 N due to the local epitaxial growth and extremely smooth coating surface, Ra = 0.012 μm due to the elimination of growth defects. The coating crystallised in fcc structure with a preferred {220} orientation. XTEM analysis revealed a nanoscale multilayer structure of the coating with carbon segregated at the column boundaries but also vertically to form a lateral phase at the interfaces between the individual nanolayers. Addition of C to CrAlYN/CrN increased the chemical inertness between cutting tool and workpiece material without deteriorating the oxidation resistance of the coating. Thermo gravimetric analysis showed that the temperature for the onset of rapid oxidation was as high as 940 °C. In dry milling of AlSi9Cu1 alloy, CrAlYCN/CrCN coated 8 mm diameter cemented carbide end mills outperformed non coated end mills by factor of 2.5 with effective hindered built up edge formation mechanism.

1118 cBNコーティング超硬エンドミルの焼入れ鋼に対する切削性能(GS-13 切削・研磨加工)

1118 cBNコーティング超硬エンドミルの焼入れ鋼に対する切削性能(GS-13 切削・研磨加工)

Influence of Plating Conditions on Cutting Performance of cBN Coated Cemented Carbide End-Mill

This study highlights the influences of pre-treatment and plating conditions on the cutting performance of cBN-coated tools. The pre-treatment evaluations investigate the profile, chemical cleaning, and bombardment conditions of the cutting edge. The plating condition evaluation concerns the influence of TiN and cBN plating conditions. In this paper, TiN plating is employed as a pre-process of cBN plating. Moreover, developed cBN-coated cutting tools were used to conduct cutting experiments for hardened die steel and austenitic structure stainless steels. The results show that the new cBN-coated cutting tools demonstrate effective performance for practical use in industrial applications.