Andre Batako

Application of Minimum Quantity Lubrication in Grinding

Fluid delivery in grinding process remains an important matter requiring further research. The growing demand and the rising cost of cutting fluid usage and the environmental aspect of fluid disposal are a key driver for research into alternative fluid delivery techniques. One of the alternative fluid reduction methods employed in machining is minimum quantity lubrication (MQL). In specific grinding operations, MQL is capable of maintaining or even reducing temperature, yet using extremely small amounts of lubricant. Therefore, MQL addresses not only more economical production costs but also a critical matter of the natural and worker environment protection. This article reviews application of the MQL technique in abrasive machining in comparison to conventional and dry grinding. Common steels EN8, M2, and EN31 were ground with a general purpose alumina wheel. Results obtained determined that MQL performance can be compared to flood delivery under the conditions investigated. In some specific conditions, MQL achieved better results. Performance indicators included: grinding power, specific forces (tangential and normal), grinding temperature, and workpiece surface roughness.

Modelling of vibro-impact penetration of self-exciting percussive-rotary drill bit

Abstract The penetration of a drilling tool into a hard medium under periodic impact action is analyzed and the simulation model presented. This is further development of previously investigated model of a self-excited percussive-rotary drilling system. The system used the stick–slip phenomenon to generate an impact action superimposed on the drilling process. A phenomenological visco-elasto-plastic model of the media is used and the system response is studied numerically, first as a forced vibration and second as a result of a self-excited vibro-impact process. Relief of the main drive has been obtained and an increase in the rate of penetration is observed with increased impact intensity and hardening of the medium. Results of the preliminary drilling experiment with superimposed dynamic action have shown an improvement in the rate of penetration.

Influence of thermal loads on the stress-strain state of aluminum-oxide ceramic cutting plates

The influence of thermal loads on the stress-strain state of oxide-ceramic cutting plates is investigated; in the analysis, the nonlinear properties of aluminum oxide and gray iron are taken into account. Requirements are formulated on the properties of aluminum-oxide cutting plates.

A study of the cutting properties and wear mechanism of ceramic edge tools with nanostructure multilayer composite coatings

The paper presents the results of studies of the cutting properties and wear mechanism of the edge cutting tool equipped with replaceable indexable inserts made of cutting ceramic with nanoscale multilayer composite coatings when cutting hardened steel. It has been shown that applying the latter allows one to tune the contact processes based on the changes in friction and lengths of dense and complete contacts between the chip and the rake face of the cutting tools, thereby reducing normal contact strains and the probability of macro- and microbrittle fracture in the contact areas of the tool.

Friction-driven vibro-impact system for percussive-rotary drilling: A numerical study of the system dynamics

Stick—slip-induced vibration in drilling has a detrimental effect on the drilling system and may lead to the failure of the drill string. This study is a further development of a friction-driven vibro-impact system which was investigated previously. The system used the stick—slip properties to generate a vibratory motion of a hammer that collides with the bit. The previous study focused on the influence of the friction on the response of the system without impacts. This paper investigates the full dynamic response of the model including friction and impact. Numerical bifurcation analysis of the system is undertaken to establish various motions and dynamical changes. This study focuses on the system performance outside the stable interval identified in the earlier investigation. The response of the system is illustrated along with the phase portraits.

Improvement of structure and quality of nanoscale multilayered composite coatings, deposited by filtered cathodic vacuum arc deposition method

This article studies the specific features of cathode vacuum arc deposition of coatings used in the production of cutting tools. The detailed analysis of the major drawbacks of arc-Physical Vapour Deposition (PVD) methods has contributed to the development of the processes of filtered cathodic vacuum arc deposition to form nanoscale multilayered composite coatings of increased efficiency. This is achieved through the formation of nanostructure, increase in strength of adhesion of coating to substrate up to 20%, and reduction of such dangerous coating surface defects as macro- and microdroplets up to 80%. This article presents the results of the studies of various properties of developed nanoscale multilayered composite coating. The certification tests of carbide tool equipped with cutting inserts with developed nanoscale multilayered composite coating compositions in longitudinal turning (continuous cutting) and end symmetric milling, and intermittent cutting of steel C45 and hard-to-cut nickel alloy of NiCr20TiAl showed advantages of tool with nanoscale multilayered composite coating as compared to the tool without coating. The lifetime of the carbide inserts with developed NMCC based on the system of Ti–TiN–(NbZrTiCr)N (filtered cathodic vacuum arc deposition) was increased up to 5–6 times in comparison with the control tools without coatings and up to 1.5–2.0 times in comparison with nanoscale multilayered composite coating based on the system of Ti–TiN–(NbZrTiCr)N (standard arc-PVD technology).

Nanostructured Multilayer Composite Coatings on Ceramic Cutting Tools for Finishing Treatment of High-Hardness Quenched Steels

The functional role of nanostructured multilayer composite coatings (NMCC) deposited on the operating surfaces of replaceable faceted cutting inserts (CI) from cutting ceramics based on aluminum oxides with additives of titanium carbides is studied. It is shown that the developed NMCC not only raise substantially the endurance of the ceramic tools under high-speed dry treatment of quenched steels but also improve the quality and accuracy of processing of the parts and the ecological parameters of the cutting process.

Influence of ceramic properties on the stress-strain state of a plate in steady heat conduction

For ceramic cutting plates, the influence of their thermal conductivity, the elastic modulus, and the temperature coefficient of linear expansion on the stress-strain state is considered, in conditions of steady heat conduction.

An Analysis of Ship Hull Vibration Failure Data

ABSTRACT In this paper, failure data collected from a classification society is presented and an analysis is carried out to determine the major causes of Ship Hull Vibration (SHV).The failure data collected is focused on Propulsion System Vibration (PSV) defects and SHV defects. The major causes which create SHV are discussed and final conclusions and recommendations are given.

Process monitoring in high efficiency deep grinding- HEDG

High Efficiency Deep Grinding (HEDG) is an emerging technology that allows grinding to be undertaken at high wheelspeeds (up to 250 m/s), relatively large depth of cut (1 to 25 mm or more) and extremely high workspeeds up to 1000 mm/s. However, this new technology is not fully understood, thus it needs further investigation into machining requirements in order to develop adequate strategies to control the process. Various sensors are used to monitor the process performance in grinding. Thermocouple technique is commonly used and has advantages of low-cost, ease of use and direct surface temperature measurement. Temperature measurement is particularly challenging in deep grinding with cuts that may exceed 5 mm and high workspeeds approaching 1 m/s. Grinding coolant and electrical noise cause further challenges for achieving accurate and reliable temperature measurement. A single-pole thermocouple technique that provides reliable measurements is presented. This paper presents various grinding force measurement techniques and the thermal modelling that has been used to predict temperature in the HEDG process as a function of cutting parameters. Results obtained for in-process monitoring of the high efficiency deep grinding using the power and temperature measurements are presents.