Wisley Falco Sales

Application of cutting fluids in machining processes

In the last decade a lot has been discussed about the suitability of using cutting fluid in abundance to cool and lubricate machining processes. The use of cutting fluid generally causes economy of tools and it becomes easier to keep tight tolerances and to maintain workpiece surface properties without damages. In the other hand, it brings also some problems, like fluid residuals and human diseases. Because of them some alternatives has been sought to minimise or even avoid the use of cutting fluid in machining operations. Some of these alternatives are dry cutting and cutting with minimum quantity of fluid (MQF). The main goal of this work is to discuss these tendencies. Therefore, topics like kinds and methods of applications of modern cutting fluids and what are new in this area will unavoidably be considered. MQF and dry cutting techniques, their applications and where it is not possible to apply them will also be focused. To exemplify the topics, this work will describe some of the researches been developed in two important Brazilian Universities: State University of Campinas (UNICAMP) and Federal University of Uberlândia (UFU).

Cooling ability of cutting fluids and measurement of the chip‐tool interface temperatures

Many machining researches are focused on cutting tools mainly due to the wear developed as a result of high temperatures generated that accelerate thermally related wear mechanisms, consequently reducing tool life. Cutting fluids are used in machining operations to minimize cutting temperature although there is no available indicator of their cooling ability. In this study, a method to determine the cooling ability of cutting fluids is proposed. A thermocouple technique was used to verify the chip‐tool interface temperature of various cutting fluids during turning operation. The method consists of measuring the temperature drop from 300°C up to room temperature after heating a standardised AISI 8640 workpiece and fixing it to the chuck of a lathe and with a constant spindle speed of 150 rpm the cutting fluid was applied to a specific point. The temperature was measured and registered by an infrared thermosensor with the aid of an AC/DC data acquisition board and a PC. The convective heat exchange coeffici...

Burr formation in face milling of cast iron with different milling cutter systems

Abstract Two face milling cutter systems, both with PCBN (polycrystalline cubic boron nitride) tools, were used to study burr formation in high-speed machining of grey cast iron under various cutting conditions. Surface roughness parameters Ra and Ri, tool life (based on flank wear, VBmax) and burr formation (length of the burr, h) were recorded and used for comparing machining performance. The best performance in terms of tool life and surface roughness was obtained with the milling cutter system consisting of 24 teeth and 24 square wiper inserts. Machining with this cutter configuration produced acceptable surface roughness values, well below the rejection criterion, after machining a batch of 3000 motor blocks in addition to achieving a significant reduction in the burr length.

Tribological behaviour when face milling AISI 4140 steel with minimum quantity fluid application

Purpose – The purpose of this paper is to evaluate the performance of cutting fluid applied by minimum quantity technique when milling AISI 4140 steel with TiAlN coated cemented carbide inserts.Design/methodology/approach – The vegetable oil based cutting fluid evaluated was applied through a nozzle at the centre of the tool holder under vaporized conditions with a flow rate between 0 (dry cutting) and 200 ml/h, at 50 ml/h increments. Tool wear (based on maximum flank wear, VBmax), surface roughness parameters (Ra and Rt) and burr formation (length of burr, h) were recorded and evaluated. Scanning electron microscope images and energy dispersive X‐ray analysis of the worn tools show adhesion as the dominant wear mechanism.Findings – Encouraging tool performance was recorded when milling AISI 4140 steel due to improved lubrication and cooling at the cutting interfaces. Increase in cutting fluid flow rate improves tool life with gradual reduction of the surface roughness parameters and negligible influence ...

Influence of machining parameters on fatigue endurance limit of AISI 4140 steel

The general purpose of this research is to study the influence of commercial machining parameters on fatigue limits of steels. Specifically in this work, the influence of cutting speeds, depth of cut, feed rate and residual stresses of turned surfaces of AISI 4140 steel specimens on fatigue strength were analyzed. In some specimens, the residual stress was eliminated by heat treatment. The fatigue experiments were carried out at room temperature, applying a cyclical frequency of 58Hz, with mean stress equal to zero (R=-1), on a rotating-bending fatigue testing machine of the constant bending moment type. It was used the staircase (or up-and-down) method to determine the fatigue limit of the specimens.

Evaluation of cutting fluids using scratch tests and turning process

This work demonstrates that scratch test techniques can be used to provide a quick and cost effective evaluation of cutting fluids. Apparent coefficient of friction and specific energy for the scratch steel samples under several lubrication conditions provides a good indicator of cutting fluid performance. This is followed by evaluation of the surface finish and the cutting force of the ABNT NB 8640 steel with emulsion and synthetic cutting fluids, at 5% of concentrations, and neat mineral oil in the turning process. Comparative tests were carried out under dry and wet conditions. Results show that the linear scratch test was not efficient while the pendular scratch test was efficient tool in the classification of cutting fluids. The results can be transferred to conventional machining due to its dynamic nature.

Overview of the Machining of Titanium Alloys

Machining of titanium alloys has always attracted considerable great interest in the manufacturing sector as well as within the scientific research community worldwide. Titanium alloys are widely employed in aero-engine and for airframe manufacture because of their outstanding strength to density ratios relative to other materials. Due to the expensive cost of titanium alloys, relative to other metals, attributed mainly to the complexity of the extraction process, difficulty of melting and problems during fabrication and machining, integrated researches have been established globally to improve their machinability. Success in the machining of titanium alloys can be achieved by employing the correct selection of cutting tools, cutting environment, and appropriate cutting conditions for each machining operation. This article reviews the machining of titanium alloys, highlighting the main cutting tools, cutting parameters, and cooling environments that have been employed in last three decades. The purpose is to enhance the general understanding of practitioners and researchers on the principles of machining titanium alloys, the properties that impair their machinability, performance of different cutting tools, wear mechanisms, and dominant failure modes of cutting tools under different machining conditions, including various techniques that enhance the machining of titanium alloys. A good understanding of these parameters as well as processing time and functionality of the machined component will lead to efficient and economic machining of titanium-base superalloys.

Machining Dynamics in Turning Processes

The dynamic stability of a machine tool in the turning process depends essentially on the compliance of the lathe turning structure, as well as on the properties of the cutting process [1]. However, the design of the machine tool, the material(s) employed for its manufacture and their mechanical properties are extremely important for the dynamic behaviour of the machining system (comprising the entire lathe and the work material) [1-13]. Theoretical details of dynamic stability and how to quantify, measure and monitor them as well as other phenomena such as chatter (self-excited vibration) and forced vibration have been covered in previous chapters. This chapter will, therefore, focus on the illustration and the discussion of practical details regarding the turning process. The influence of the input on the output parameters will be evaluated with regards to the dynamic stability in a turning process. The main input parameters affecting the machining system vibration are: work material, work material geometry, tool material, tool geometry, lathe rigidity, cutting conditions (cutting speed, vc, feed rate, f and depth of cut, doc) and tool wear. The behaviour of the machining system during vibration is a major output parameter.