Efficiency of cutting tools equipped with cBN-based polycrystalline superhard materials having vacuum-plasma coating

The paper deals with the studies of improving the efficiency of cutting tools equipped with cBN-based polycrystalline superhard materials by a vacuum-plasma coating. It has been shown that the tools with coatings are characterized by an increased reliability at the stage of running-in and longer life, and allow using higher cutting parameters.     

Irregularities of the surface machined by oblique single-edged tools equipped with cBN-based polycrystalline superhard material

The results are considered of the investigation into the regularities of variation of parameters of irregularities of the surface cut by oblique single-edged tools equipped with cBN-based polycrystalline superhard material (PSHM) as a function of the cutting conditions and tool geometrics.     

New superhard material for drilling tools

The authors discuss physical-mechanical properties of a new thermostable polycrystalline diamond composite material and its potential use in rock-destruction tools for drilling wells in hard rock. The paper presents the results of investigation aimed at clarifying the effect of dimensions of inserts made of this new material on the drilling tool performance. An optimal size of inserts to be set in the bit face has been established which improves hard rock drilling efficiency in comparison to conventional tools.     

Tribology of cutting by tools equipped with cBN-based PSHM

Mechanisms of the contact interaction between the cutting tool equipped with cBN-based PSHM and the material machined in the cutting zone have been considered. The influence of the thermobaric conditions of loading on the tool (cutting temperature and contact stresses) on the mechanisms has been discussed.     

The study of wear of cutting tools of cBN-based composite material and the influence of tool wear on cutting forces in turning hardened steels

The paper presents some findings of the investigation of finish turning of KhVG hardened steel using a cutting tool with an insert made of a cubic boron nitride based composite (cBN-Si₃N₄ system). The behavior of tool wear throughout the machining time as well as the influence of the tool wear on cutting force components and resulting cutting force have been clarified.     

Development and application of the Cu-Ni-Fe-Sn-based dispersion-hardened bond for cutting tools of superhard materials

Bonds based on Cu-Ni-Fe-Sn alloy and dispersion-hardened with W, WC, NbC, Al₂O₃, ZrO₂, Si₃N₄, and BN nanoparticles have been developed for the use in diamond tools designed for cutting reinforced concrete and refractory materials. The paper addresses special features of cold pressing and sintering of binder/nanoparticles mixtures as well as physical-mechanical and tribological properties of compact materials. The use of the proposed dispersion-hardened bonds has provided up to 3.5-times longer tool life without decreasing cutting efficiency.     

The study of the influence of cutting conditions on machined surface roughness in turning hardened steels with cutting tools of cBN-based composite

The paper presents some findings of the investigation of finish turning of KhVG hardened steel using a cutting tool tipped with a round insert made of a composite based on cubic boron nitride (cBN-Si₃N₄ system). Based on the analysis of machined surface roughness, the cutting conditions have been found which ensure a stable interaction between the cutting tool and the workpiece.     

Intelligent design of cutting tools using smart material

Shaving metal from a workpiece to produce desired geometric shape is carried out in turning machine tool. Attenuating a micro level vibration of a cutting tool using smart materials can save old machines and enhance flexibility in designing new generations of machine tools. The finite element method is employed to investigate structural stiffness, damping, and switching methodology using smart material in tool error attenuation. In this work, a dynamic force model is deployed to investigate the effectiveness of using such technique in toolpost dynamic control. Effects of short and open circuit conditions on tool critical frequencies for different structural stiffness ratios are assessed. In the transient solution for tool tip displacement, the pulse width modulation (PWM) technique is implemented for smart material activation to compensate for the radial disturbing cutting forces. A Fuzzy Algorithm is developed to control actuator voltage level enhancing improved dynamic performance. The influence of minimum number of PWM cycles in each disturbing force cycle is investigated in controlling the tool error growth. A methodology is developed to utilize toolpost static force–displacement diagram to obtain required activation voltage to shrink error under different dynamic operating conditions. Time delay of applied voltage during error attenuation is evaluated at different frequencies.     

Wear and life of tools with inserts from cBN-based polycrystalline Superhard materials in the finish turning of hardened steels at heavy feeds

The results have been considered of experimental studies of the wear regularities of tools with polycrystalline superhard materials based on cubic boron nitride (PCBN) in high-performance finishing of hardened steel with oblique cutters. The effect of machining conditions on the life of such tools has been analyzed.     

Soft PVD Coatings — a new coating family for high performance cutting tools

The joint effort of a cutting tool manufacturer and a coating specialist led to the development of a soft solid lubricant based cutting tool coating (Patents pending!). It is applied by an advanced sputtering technique as a very thin uniform coating with a good adherence to the tools. It has a low coefficient of friction and a low affinity to alloy materials like aluminum, titanium and precious metals. These factors and others allow the machining at high spindle speed and feed rates with an excellent workpiece surface finish. Values can be maintained which are far superior to even those permitted for cemented carbide tools. In some cases, productivity and tool life can be increased by a factor of up to 20.     

A lean environmental benchmarking (LEB) method for the management of cutting tools

Manufacturing companies are striving hard to remain competitive hence, they rely on a number of resources to meet customers’ expectations, among which cutting tools are included. This paper addresses the problems faced in the management of cutting tools activities. Production managers have highlighted the lack of procedures containing metrics and targets that would show them whether their company is able to perform an efficient management, and if it is capable of supporting the deployment process. In this context, this paper presents a novel lean environmental benchmarking (LEB) method for performing a diagnosis of practices and performances to support the implementation of a cutting tool management strategy and/or the effective management of these assets. Strategic, technical and logistical aspects are addressed, particularly, with regard to management focused on lean manufacturing and environmental aspects. Field studies were performed in nine Brazilian companies in the metal-mechanical sector to validate the LEB method proposed. The LEB method helped the participant organisations to clarify the various activities that involved the management of their cutting tools, while the field studies indicated that all nine organisations had a great concern regarding the preservations of the environment, and also an effective utilisation of resources spent for machining components.     

Special features of the applications of cutting tools from polycrystalline cubic boron nitride with protective coatings

The results of the investigations on the efficiency of cutting tools from polycrystalline superhard materials based on cubic boron nitride with a protective coating. A hypothesis is proposed for the increase of the cutting tool life in turning hardened steel due to a decrease of the temperature in the cutting zone and a complex of physico-mechanical properties of the protective coating required for this is analyzed. A protective coating of boron nitride is considered in the amorphous state that plays a role of a solid lubricant in the zone of the tool contact with cutting chips, decreases the temperature in the contact zone through the reduction of the contact length and cutting force, ensures an increase of the tool life and reliability, especially at the stage of the run-in.     

Non-catalytic facile synthesis of superhard phase of boron carbide (B13C2) nanoflakes and nanoparticles

Boron Carbide is one the hardest and lightest material that is also relatively easier to synthesis as compared to other superhard ceramics like cubic boron nitride and diamond. However, the brittle nature of monolithic advanced ceramics material hinders its use in various engineering applications. Thus, strategies that can toughen the material are of fundamental and technological importance. One approach is to use nanostructure materials as building blocks, and organize them into a complex hierarchical structure, which could potentially enhance its mechanical properties to exceed that of the monolithic form. In this paper, we demonstrated a simple approach to synthesize one- and two-dimension nanostructure boron carbide by simply changing the mixing ratio of the initial compound to influence the saturation condition of the process at a relatively low temperature of 1500 degrees C with no catalyst involved in the growing process. Characterization of the resulting nano-structures shows B13C2, which is a superhard phase of boron carbide as its hardness is almost twice as hard as the commonly known B4C. Using ab-initio density functional theory study on the elastic properties of both B12C3 and B13C2, the high hardness of B13C2 is consistent to our calculation results, where bulk modulus of B13C2 is higher than that of B4C. High resolution transmission electron microscopy of the nanoflakes also reveals high density of twinning defects which could potentially inhibit the crack propagation, leading to toughening of the materials.     

Analysis of coating interlayer between silicon nitride cutting tools and titanium carbide and titanium nitride coatings

Silicon nitride (Si₃N₄) cutting tools exhibit excellent thermal stability and wear resistance in the high-speed machining of cast irons, but show poor chemical wear resistance in the machining of steel. Conventional chemical vapour deposition (CVD) coating of Si₃N₄ tools has not been very successful because of thermal expansion mismatch between coatings and the substrate. This problem was overcome by developing a CVD process to tailor the interface for titanium carbide (TiC) and titanium nitride (TiN) coatings. Computer modelling of the CVD process was done to predict which phases would form at the interface, and the results compared with analyses of the interface. Three Si₃N₄ compositions were considered, including pure Si₃N₄, Si₃N₄ with a glass phase binder, and Si₃N₄ + TiC composite with a glass phase binder. Results of machining tests on coated tools show that the formation of an interlayer provides superior wear resistance and tool life in the machining of steel as compared to uncoated and conventionally coated Si₃N₄ tools.     

Effect of the microstructure on the cutting performance of superhard (Ti,Si,Al)N nanocomposite films

A d.c. reactive magnetron sputtering technique was used to deposit (Ti,Si,Al)N coatings onto WC-Co cutting tools. The microstructure of the coatings was analysed using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) measurement. Before the cutting experiments, the XRD results revealed a structure indexed to an fcc TiN. The results obtained by the XRD tests, with detector variation in asymmetric mode (rocking curves) showed a decrease in the quality of the fiber texture in the (111) grains with the change on deposition chamber geometry (two magnetrons in place of four magnetrons). Cross-sectional HRTEM images of the (Ti,Al)N sample showed grains with a diameter between 16 and 30 nm, while for the (Ti,Si,Al)N samples grains with a diameter between 6 and 10 nm were observed. Furthermore, through the visualization of bright field images it was possible to discern a columnar structure. For samples prepared at high deposition rates (2 μm/h), HRTEM micrographs revealed the formation of the multilayer stacking of (Ti,Si)N/(Ti,Al)N.     

The study of the influence of wear of a cutting tool of cBN-based composite material on the tool fracture probability in the finish turning of hardened steels

The authors have experimentally clarified the influence of the tool wear on the tool fracture probability in the finish turning of hardened steels of various hardness values using a tool with a round cutting insert of cBN/Si₃N₄ composite. The maximum stresses and fracture probability have been determined for the tool face and flank. Recommendations regarding the use of cBN/Si₃N₄-inserted cutting tools are provided.     

The study of the influence of wear of the cutting tool with an insert of cBN-based composite material on the tool vibrations in finish turning of hardened steels

It has been found out that wear of a cutting tool with an insert of cBN-based composite material has an effect on the tool vibrations in finish turning of hardened steels with various hardness values. The influence of the tool vibrations on the machined surface roughness has been studied.     

Valuation of a Cellulose Acetate (CA) latex as coating material for controlled release products

Cellulose acetate (CA) latex plasticized with 150% triacetin (TA) and 120% triethylcitrate (TEC), based on polymer weight, provided dense and homogeneous films when deposited onto propranolol HCl tablets using conventional fluid bed technology. Film permeability to the drug was low and flux/permeability enhancers were added to the CA structure during its manufacture. Films containing 40% surcrose and 10% PEG 8000 were found to provide the best release characteristics in terms of small lagtime (1 hour) and drug release profile (over 12 hours). When sucrose was added to TA or TEC plasticized fimls, a macroporous membrane was created during exposure to the dissolution fluid due to sucrose release from the film. These observations are consistent with the controlled porosity walls previously described for CA films deposited from organic solvents. It was postulated that drug mass transport occurs mainly within the porous CA structure and the mechanism responsible for its is a combination of molecular diffusion/osmotic pressure via water transport into the porous cellulose acetate membrane. Plasticizer loss during drying had also been demonstrated and related to the change in release profile seen with drying time.