Lubrication in metal cutting under built-up edge conditions

The effect of a mineral oil lubricant and sulphur (an EP additive) on machining of medium carbon steel has been investigated. The lubricant was applied with several different concentrations an additive containing sulphur. The concentrations were 0%, 1 %, 2%, 3%, 4% and 5% of the additive. The results were compared with dry conditions. The effect of cutting speed and feed rate was also investigated. During the tests cutting force, transient surface temperature and surface finish were measured. Cutting force and surface finish were measured using traditional equipment. measure the temperature of the workpiece a new method was developed. The temperature of the transient surface was measured at three different positions below the cutting edge during the cut using an infrared sensor. The results were then extrapolated to obtain the temperature of the transient surface close to the cutting edge (the maximum temperature of the surface). The temperature results can be used to calculate the cooling rate of the surface. Quick stop tests were also used to obtain chip samples and information about BUB size and shape. The lubricant had no effect on forces, temperature or BUB size, but improved surface finish. This works suggests that the enhanced surface finish obtained when lubricant is applied is not due to lubrication on the rake face (preventing a BUE), but action on the machined surface after it has been formed. The BUE is squeezed parallel to the cutting edge and touches the workpiece altering the surface finish, by a rubbing action and also because periodically part of the BUB bonds to the surface. The lubricant works on this rubbing action and can avoid bonding of the squeezed BUE and also of debris particles that are inevitably formed during the operation. It has been shown that a very low volume of lubricant is enough to improve the surface finish because the area that requires lubrication is small

Proposta de trabalho: Estudo da influência da aplicação de fluido de corte à alta pressão durante o fresamento do aço ABNT 1045 / Work Proposal: Study of the influence of high pressure cutting fluid application during milling of ABNT 1045 steel

A aplicação de fluido de corte à alta pressão cada vez mais vem sendo alvo de investigação sobre seu uso durante os processos de usinagem. Isto é resultante dos benefícios promovidos por esta técnica, que devido ao alto poder de penetração na zona de corte, pode influenciar diretamente na redução de calor gerado durante a formação do cavaco e também na redução do atrito entre o cavaco e a ferramenta. Outra vantagem da aplicação de fluido de corte à alta pressão é aumentar a vida da ferramenta beneficiando o acabamento superficial de peças usinadas, além de auxiliar na remoção e controle do cavaco, proteger a máquina ferramenta contra a corrosão atmosférica, etc. Este trabalho baseia-se na investigação da aplicação do fluido de corte à alta pressão e seus impactos na rugosidade da superfície usinada, na evolução do desgaste em ferramentas de corte e nos esforços de usinagem. Os testes serão realizados no processo de fresamento frontal, em um centro de usinagem CNC da marca Romi, modelo D1250, com sistema de refrigeração interna pelo eixo árvore. O material a ser usinado será uma liga de aço comum ao carbono ABNT 1045. Os experimentos serão comparados com a usinagem à seco e com fluido aplicado na forma de jorro. A pressão máxima de aplicação do fluido de corte será mantida constante em 7Mpa. As ferramentas utilizadas, serão pastilhas de metal duro da classe ISO P, revestidas com TiAlN, utilizando a técnica de deposição de vapor físico (PVD). Deste modo, este trabalho visa analisar a viabilidade da utilização da técnica de aplicação de fluido de corte em alta pressão, comparados com a forma tradicional e na usinagem à seco, a fim de propiciar o desenvolvimento de novas técnicas de uso do fluido de corte, de forma sustentáveis e economicamente viáveis de lubri refrigeração em processos de fabricação

Study of the internal thread process with cut and form taps according to secondary characteristics of the process.

The internal threading with tap or forming tap, is a widely applied factoring process throughout industry. However, the knowledge held by the toolmakers is not transferred to the scientific literature, which justifies the small number of studies regarding this matter. This data limitation reduces the tool and cutting condition selection guide to geometrical characteristics. This current work has twomain goals; the first one is to study the process behavior regarding the secondary and uncontrollable characteristics, such as thread length, tool coating, feed rate, and hole?s diameter. It also investigated the load distribution in the cutting edge for a tap operation. The second goal of this work is the investigation of the behavior of a new type of floating system in terms of torque and axial force. One of the outcomes of this work was that the torque distribution along the fillet was not uniform, with the torque of the third fillet higher than the others. The floating system tested reduces the axial force and torque by reducing synchronicity errors even in extremely conditions

A Probabilistic Neural Network Applied In Monitoring Tool Wear In The End Milling Operation Via Acoustic Emission And Cutting Power Signals

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Tool condition monitoring, which is very important in machining, has improved over the past 20years. Several process variables that are active in the cutting region, such as cutting forces, vibrations, acoustic emission (AE), noise, temperature, and surface finish, are influenced by the state of the cutting tool and the conditions of the material removal process. However, controlling these process variables to ensure adequate responses, particularly on an individual basis, is a highly complex task. The combination of AE and cutting power signals serves to indicate the improved response. In this study, a new parameter based on AE signal energy (frequency range between 100 and 300kHz) was introduced to improve response. Tool wear in end milling was measured in each step, based on cutting power and AE signals. The wear conditions were then classified as good or bad, the signal parameters were extracted, and the probabilistic neural network was applied. The mean and skewness of cutting power and the root mean square of the power spectral density of AE showed sensitivity and were applied with about 91% accuracy. The combination of cutting power and AE with the signal energy parameter can definitely be applied in a tool wear-monitoring system.203386405CNPq (National Council for Scientific and Technological Development)CAPES (Federal Agency for the Support and Improvement of Higher Education)FAPEMIG (Minas Gerais State Research Foundation)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Estimation of a Moving Heat Source due to a Micromilling Process Using the Modified TFBGF Technique

Moving heat sources are present in numerous engineering problems as welding and machining processes, heat treatment, or biological heating. In all these cases, the heat input identification represents an important factor in the optimization of the process. The aim of this study is to investigate the heat flux delivered to a workpiece during a micromilling process. The temperature measurements were obtained using a thermocouple at an accessible region of the workpiece surface while micromilling a small channel. The analytical solution is calculated from a 3D transient heat conduction model with a moving heat source, called direct problem. The estimation of the moving heat source uses the Transfer Function Based on Green’s Function Method. This method is based on Green’s function and the equivalence between thermal and dynamic systems. The technique is simple without iterative processes and extremely fast. From the temperature on accessible regions it is possible to estimate the heat flux by an inverse procedure of the Fast Fourier Transform. A test of micromilling of 6365 aluminium alloy was made and the heat delivered to the workpiece was estimated. The estimation of the heat without use of optimization technique is the great advantage of the technique proposed

An?lise da temperatura filete a filete no rosqueamento interno por machos de corte.

Among the manufacturing processes, threading stands out, as it can be accomplished by machining or by forming. This process is responsible for the creation of internal and external threads, which has great applicability in production lines. Due to the market?s great competitiveness, methods are sought to increase production by decreasing the time of each unit process. However, tapping is usually performed at low cutting speeds due to limitations related to the manufacturing process. The study of the tapping can bring benefits, such as the reduction of wear mechanisms, resulting in an increase in tool life. In this research, the temperature was measured from fillet to fillet in the conical part of the tool, varying the cutting speed and the number of fillets. The tap used is, M 10 x 1.5 HSS, uncoated in threading process for internal thread production in SAE 1045. To analyze the temperature was used the tool-workpiece thermocouple method on each fillet of the tap. The cutting speeds used were 10 and 25m / min. From the second fillet on the temperature is constant, even with the increase in the number of fillets, as expected

An approach to torque and temperature thread by thread on tapping.

During internal threading, small alterations in cutting parameters, tool geometry, or process characteristics produce considerable effects on torque and temperature behavior. Understanding these effects is critical to the design and development of new taps. In this work, the torque behavior for a tap operation is evaluated as a function of the number of threads, tool manufacturer, and angle of the taper region of the tool. The chip?tool interface temperature was analyzed, considering the influence of cutting speed and number of threads. Experimental tests were carried out using M10x1.5 taps and cutting speeds of 10 m/min and 25 m/min. Taps with two different geometries were considered in this analysis. The results show a difference in the distribution of the torque along the threads of the conical part between the tools. The presence of adhered material increased the torque during the reverse stage. The torque during the reverse stage for a tap with a damaged tooth was approximately 50% of the torque during the cutting stage. The temperature showed an increase with the number of threads stabilizing between the fourth and fifth threads and increasing again in the sixth filled due to adhesion of workpiece material

Study of machinability of VP 100 steel with different levels of titanium in end milling operations

During the manufacture of a mould, machining is certainly the most important process. The composition required to provide important properties in the steels used, such as hardness, wear and corrosion resistance, results in a low machinability has resulted in a low volume of material removed by the end of life of the cutting tool, due to the strong wear generate. In this study, we investigated the behavior of steel processing VP 100 is used in manufacturing plastic injection molds. To this end, we used two versions of VP100, one with 270 and another with 350 parts per million (ppm) of titanium. The tests comprise six different cutting conditions in end milling operations. We observed the volume of material removed for each tested condition, considering the evolution of flank wear of tools to a maximum of0.5 mm. Steel VP 100 with 350 ppm of Ti showed a higher volume of material removed in five of six tests showing that, in this case, a higher content of titanium improved the machinability of the steel under study.