Ceramic End Mills Research Articles

Chatter failure comparison for high-speed milling of aerospace GH4099 with silicon nitride ceramic end mills: A laboratory scale investigation

Chatter generated in the high-speed cutting process can seriously limit the machining efficiency and affect the surface machining quality, which urgently needs to be controlled. Aiming at brittle ceramic end mills that are very sensitive to vibration, a strategy based on the modal experimental method is proposed to construct effective and accurate stability lobe diagram (SLD) for chatter prediction and failure analysis in this work. Firstly, the tool tip frequency response function (FRF) of four kinds of self-developed ceramic end mills and commercial cemented carbide end mills with the same structure are established by means of hammering modal experiments, and the modal parameters are solved and identified. Then, based on our established high-speed milling chatter prediction model, the milling force coefficients are obtained by linear regression analysis and calculation, thereby the milling SLDs of five end milling tools are developed. Finally, a series of high-speed side milling experiments are carried out using consistent cutting conditions. The results show that the constructed SLDs can effectively predict the chatter failure region and milling stability for five kinds of end mills, and four ceramic milling tools exhibit more excellent chatter suppression performance according to frequency domain analysis of vibration signals and the observation of workpiece surface vibration marks, in which the S4 ceramic milling tool presents the most significant high-speed milling stability.

Cutting Performance and Wear Behavior of Self‐Developed Silicon Nitride Ceramic End Mills with Optimized Structure for High‐Speed Machining of GH4099

Ceramic tool materials possess a wide range of potential in machining nickel‐based superalloys due to their superior wear resistance, high‐temperature hardness, and strong chemical stability. Herein, a structural optimization scheme of self‐developed silicon nitride ceramic end mill based on stiffness enhancement and performance improvement is proposed, and the key geometric angular parameters scope of the self‐developed ceramic end mills are prioritized via the finite‐element simulation method. Through precision grinding manufacturing and sandblasting pretreatment, the cutting performance and tool wear behavior of three optimized self‐developed silicon nitride ceramic end mills (called S4‐1, S4‐2, S4‐3 respectively) are comprehensively analyzed in comparison, including cutting force, milling temperature, surface quality, and tool life. The results indicate that the cutting force and cutting temperature of all the optimized ceramic end mills are effectively restrained compared with the nonoptimized ceramic tool(S4), and the final workpiece surface roughness is significantly reduced. Further, better surface quality can be obtained by optimized ceramic mills. In terms of tool life, ceramic end mill with optimized construction in best can be increased by up to 1.9 times. The wear mechanism and pattern of the three optimized ceramic milling tools are similar, which is adhesive wear, diffusion wear, and notch wear. Overall, the effectiveness of the optimization scheme for ceramic end mill is successfully verified.

Spark plasma sintering of Al2O3/SiCw ceramic end mill: Grain growth kinetics, mechanical properties and cutting performance

Al2O3/SiCw ceramic end mill was prepared via spark plasma sintering (SPS). The grain growth kinetics, densification mechanism and effect of SiCw on Al2O3 ceramics were studied. Cutting performance of the Al2O3/SiCw ceramic end mill was evaluated by high-speed machining Inconel 718. The results showed that the densification mechanism of Al2O3 ceramics was dominated by grain boundary diffusion when the sintering temperature was lower than 1500 °C. The Al2O3/SiCw ceramic end mill with a 25 wt% SiCw content, prepared at 1400 °C and the holding time of 5 min, possessed the most optimal mechanical properties. The relative density, Vickers hardness and fracture toughness were 99 ± 0.1%, 21.9 ± 0.8 GPa and 6.9 ± 0.4 MPa m1/2, respectively. The ceramic end mill exhibited satisfactory performance in cutting with Inconel 718 workpieces, and the tool failure was mainly caused by wear.

Geometric Structures for Sialon Ceramic Solid End Mills and Its Performance in High-Speed Milling of Nickel-Based Superalloys

Sialon ceramic tool material has become one of the most ideal materials for the high-speed cutting of superalloy materials. However, studies on the geometric structure of sialon ceramic solid end mill is lacking at the present. In this work, the geometric structure of sialon ceramic end mills was designed for difficult-to-machine nickel-based superalloy materials. The cutting force and heat, flank wear and machined surface quality were analyzed to study the effect of the main parameters on tool performance. The results showed that the end mill experienced severe flank wear and chipping, which were the leading cause of its failure during high-speed cutting. The cutting force and temperature decreased gradually with the increase in the helix angle. With the increase in the rake angle, the flank wear and the quality of the machined surface of the specimen first decreased and then increased. With the increase in the relief angle, the cutting temperature of the ceramic end mill gradually decreased, and the cutting force and the machined surface roughness showed an initial decrease and then increased. When the helix angle, rake angle and relief angle were 35°, −15° and 12°, respectively, the sialon ceramic end mill exhibited the best cutting performance and obtained better machined surface quality in the nickel-based superalloys.

Effect of MQL condition on cutting performance of high-speed machining of GH4099 with ceramic end mills

Ceramic tool materials become an ideal choice for machining superalloy materials because of the excellent tolerance to effect of heat, strong chemical stability and high temperature hardness. The present paper focuses on the effects of different cutting environments which are the dry, MQL (pure-oil) and MQL mixed with water on the milling force in each direction, the variation of flank wear, as well as surface topography of workpiece, simultaneously analyzing in deep to the wear mechanism of the mills during distinct technological environments. The results reveal that the milling force of MQL and MQL mixed with water conditions were decreased by 12.8% and 28.2% respectively compared with the dry milling. In terms of the cutting temperature, it was also significantly reduced up to 9.2% and 17.5% separately. In addition, MQL and MQL mixed with water had been successful in improving the surface quality of the workpiece and limiting the tool wear values. Similar to the tool wear mechanism of dry milling, the wear mechanisms of ceramic end mills under MQL and MQL mixed with water were deemed adhesive wear, diffusion wear and notch wear.

Si-containing diamond-like carbon coatings to improve the wear resistance of solid ceramic end mills

The study’s purpose is to determine the rational Si content in the DLC-Si external layer of (CrAlSi)N/DLC-Si coatings deposited on α/β-SiAlON + TiN ceramics. The influence of Si content on physical and mechanical properties of coatings such as microhardness, modulus of elasticity, and friction coefficient, and wear resistance of solid ceramic end mills in machining nickel alloy NiCr20TiAl is determined.

An experimental investigation on Inconel 718 interrupted cutting with ceramic solid end mills

Solid ceramic end mills for machining heat resistant super alloys (HRSA) have the potential to generate higher material removal rates, up to one order of magnitude, with respect to standard carbide tools. The machining operations in aerospace industry, where large removals are required to obtain tiny and slender parts like turbine blades, is a cost-intensive task that can benefit of the adoption of ceramic solid end mills. However, these tools show a quite limited tool life, especially when used with interrupted tool engagement strategies. Moreover, they might induce heat-related problems in the workpiece material surface integrity. This paper investigates the cutting and the tool wear during milling Inconel 718 with solid ø12 mm cutting end tool made by SiAlON. The wear mechanisms are studied together with their effects on process signals as cutting forces and power, measured via external and CNC integrated sensors. The carried experimental campaign allowed to find out that tool clogging and edge chipping were the primary cutting phenomena leading the tool wear. Cutting strategy (downmilling or upmilling) produced different results in terms of tool wear sensitivity and process outputs whereas upmilling configuration showed the best results in terms of cutting signals stability and surface integrity. At the same time, cutting speed was found to increase the cutting power more in upmilling than downmilling cutting. The analysis of the forces and power demonstrated that the typical tool wear mechanisms can be traced by signal monitoring due to their high impact on cutting processes. This fact shows the good potential of signal monitoring for a better tool life evaluation.

Innovation in Ceramic End Milling

US tooling manufacturer Greenleaf has introduced a new product line in the shape of the XSYTIN-360 family of solid ceramic end mills that it says provide a range of benefits to users

Development of DLC-Coated Solid SiAlON/TiN Ceramic End Mills for Nickel Alloy Machining: Problems and Prospects

The study is devoted to the development and testing of technological principles for the manufacture of solid end mills from ceramics based on a powder composition of α-SiAlON, β-SiAlON, and TiN additives, including spark plasma sintering powder composition, diamond sharpening of sintered ceramic blanks for shaping the cutting part of mills and deposition of anti-friction Si-containing diamond-like carbon (DLC) coatings in the final stage. A rational relationship between the components of the powder composition at spark plasma sintering was established. The influence of optimum temperature, which is the most critical sintering parameter, on ceramic samples’ basic physical and mechanical properties was investigated. DLC coatings’ role in changing the surface properties of ceramics based on SiAlON, such as microrelief, friction coefficient, et cetera, was studied. A comparative analysis of the efficiency of two tool options, such as developed samples of experimental mills made of SiAlON/TiN and commercial samples ceramic mills based on SiAlON, doped with stabilizing additives containing Yb when processing nickel alloys (NiCr20TiAl alloy was used as an example). DLC coatings’ contribution to the quantitative indicators of the durability of ceramic mills and the surface quality of machined products made of nickel alloy is shown.

Selection of diamond coated silicon nitrides for use as ceramic end mills when machining glass and carbon fiber reinforced plastics

The machining of advanced materials is challenging the tooling technology. To cope this, new cutting materials and geometries are developed. In this case, four types of silicon nitride based ceramics are investigated after coating with CVD-diamond for the use as ceramic end mills. To assess the wear resistance, model wear tests and damage evaluation were carried out and evaluated. After subsequent summary of the results, ceramic and cemented carbide substrate were selected for milling of glass and carbon fiber reinforced plastic (GFRP/CFRP) The determined force distribution and wear properties of the tools are presented and discussed. The diamond coated substrates are qualified by their wear profile and the measured constant cutting forces for use in the machining of GFRP/CFRP. Finally, the crack formation progress for diamond coated silicon nitrides when machining glass and carbon fiber reinforced plastics was demonstrated.

Tool wear progression of SiAlON ceramic end mills in five-axis high-feed rough machining of an Inconel 718 BLISK

The machining of heat-resistant super alloys such as Inconel 718 is still challenging. Processes are characterized by low productivity and high tool costs compared to the machining of steel or titanium materials. SiAlON ceramics offer potential for productivity increases, but are rarely used in industrial application due to uncertainties regarding the correct machining parameters or applicable tool life criteria. In this study, a complex miniaturized high-pressure compressor blisk component was machined using ceramic end mills for the roughing operation. Based on these experiments, the productivity increase of SiAlON ceramic roughing tools was compared to conventional cemented carbide tools. Additionally, a detailed tool wear analysis was conducted. Thereby, a wear-related tool radius decrease could be observed over the machined volume and a linear approximation could be made. Multiple tools exhibited similar tool wear progression.

Investigation of Technological Parameters for Machining Toroidal Section of Solid Ceramic End Mills

Solid ceramic mills are a promising technological solution for cutting heat-resistant materials. Although nanostructured cutting ceramics has a number of valuable physical and mechanical properties providing high operational performance of mills, it has low strength. The design of a solid ceramic mills is formed by smooth surfaces without stress concentrators to ensure operability and to reduce the probability of failure. The most important structural element of solid ceramic end mill is a helical groove with a negative rake angle needed to increase surface strength. This groove can be machined with standard grinding wheels of type 1A1 or 1V1. However, the application of grinding wheels of a standard shape requires the use of reduced cutting parameters to prevent chipping on the forming sections of the cutter. Chipping can be caused by too short length of the contact line and the stress concentration at the end point of the profile of the grinding wheel, which is typically fully responsible for shaping the front surface and its transition to the tooth back. In this paper, in order to increase the contact line, we develop a new approach to designing grinding wheels for machining helical grooves of solid mills and determining rational technological and operational parameters for there use. A new approach is developed based on the fundamental principles of analytical geometry and linear algebra, numerical methods and basic axioms of the shaping theory. In this study, we have identified the key relationships between parameters determining the position of the grinding wheel relative to the workpiece and the geometrical parameters of a solid ceramic mills. The developed approach allowing to determine the specific design of the grinding wheel, depending on the initial parameters of the mill and the trajectory of the axis of the wheel relative to the mill, was implemented in the MathCAD environment.

Selecting a Coating for Ceramic End Mill Based on the Stress-Strain Behavior of its Cutting Edge. Part 1

A coating for a Si3N4 ceramic end mill was selected based on the analysis of the results of numerical simulation of the stress-strain behavior of its cutting edge. It was found that the TiC coating is more effective than TiN coating, and reduces the temperature and stresses of the cutting edge of the mill under the transient thermoelastic conditions. This is critical for reducing the intensity of micro-chipping of ceramic material during operation.

Selecting a Coating for Ceramic End Mill Based on the Stress-Strain Behavior if its Cutting Edge. Part 21

Selecting a Coating for Ceramic End Mill Based on the Stress-Strain Behavior if its Cutting Edge. Part 21

The choice of coating for the ceramic end mill, taking into account the stress-strain state of its blade. Part 1

The coating for the end mill made of Si 3 N 4 -ceramic is selected based on the analysis of the results of numerical simulation of the stress-strain state of its blade. It was found that the TiC coating is more effective than the TiN coating, which reduces the temperature and stresses in the blade of this cutter under conditions of unsteady thermoelasticity. This is crucial to reduce the intensity of chips of microvolumes of ceramics during operation. Ill. 2. Ref. 19.

The choice of coating for the ceramic end mill, taking into account the stress-strain state of its blade. Part 2

It was found that the TiC coating is more effective than the TiN coating and stabilizes the temperature distribution and structural stress heterogeneity in the surface layer of Si3 N4 ceramic adjacent to the coating. It is recommended to apply TiC coating to end mills made of Si3 N4 -ceramic intended for milling of spatially complex surfaces on nickel alloy billets. Ill. 4. Ref. 25.

Innovative principles for manufacturing of solid ceramic end mills with antifriction wear resistant coatings for milling of diffi cult-to-machine nickel alloys

Innovative technological principles for manufacturing of solid ceramic end mills, including spark-plasma sintering of ceramic workpiece based on compositions α/β-SiAlON with additives of 10 and 20 % titanium nitride, subsequent forming abrasive blasting and deposition of antifriction wear-resistant coatings of three compositions TiN—Al/TiN, TiN—AlTiN/SiN and CrTiN—AlTiN—AlTiCrN/SiN are developed and tested. Rational modes of sintering are established for powder compositions, and the composition of 80 % (90α + 10β) and 20 % TiN is recommended as the most wear-resistant composition for ceramic milling tools. The role of coatings in increasing of durability of ceramic tool during milling of INCONEL 718 nickel alloy is assessed. It is shown that TiN— AlTiN/SiN coating provides 1.7 times higher resistance of ceramic milling cutters in comparison with uncoated tools

Machining High-Temperature Alloys by Means of Solid Ceramic End Mills

The cutting of high-temperature alloys is considered. The performance of solid ceramic end mills is assessed by experimental comparison of five different designs with different geometry, in which different materials are employed. It is found that SiAlON mills outperform TiC + Al2O3 mills.

Solid Ceramic Toroidal End Mill

The possibility of designing solid ceramic end mills with different geometry is considered. A mathematical model is developed for the cutting section of the mill on the basis of functional relations between the main geometric parameters of a ceramic end mill with a toroidal cutting section. Possible correlations are analyzed among parameters determining tool performance: the shape and size of its helical rake surface, the normal rake angle in its toroidal section, and the strength of the mill. The stress is assessed by finite-element modeling in ANSYS software. The results of finite-element modeling and geometric analysis of the cutting section confirm the need to create a special recess in the toroidal cutting section.

Design of the ceramic-bladed end milling cutters with regard for their stress-strain state for the innovation technological processes. Choice of ceramics. Part 3

The inhomogeneity of stresses at the boundaries of the main structural elements of Si3N4-ceramics under conditions of unsteady thermoelasticity is studied. The created recommendations on the choice of rational ceramics for the manufacture of ceramic end mills for processing parts from hard-to-cut materials are given. Ill. 2. Ref. 5.