Lincoln Cardoso Brandão

Turning hardened steel using coated carbide at high cutting speeds

The present work studies some aspects of the turning process applied on hardened steel using multilayer coated carbide tools at high cutting speeds. The influence of cutting parameters (vc, f, and depth of cut - d.o.c.) on tool temperature, tool wear, cutting forces, and surface roughness were analyzed. The current literature reports many studies using PcBN on hardened steel, but it is also important to know the results when using coated carbide tools, mainly for economical reasons. Temperature was measured by a thermocouple positioned at the lowest insert face, underneath it. Temperature near the rake face was calculated using the measured gradient within the insert thickness. To measure the gradient a special technique was used with one embedded thermocouple near the rake face and one underneath. Tool wear measurements demonstrated the capability of such tools in turning hardened steel with reasonable tool life. Forces measured resulted in relatively low values, being the radial component the largest of all. For the different cutting conditions studied, the doc has the greatest influence on force and temperature. Additionally, the best surface roughness values were smaller than 0,4 µm Ra.

Experimental and theoretical study on workpiece temperature when tapping hardened AISI H13 using different cooling systems

Tapping operations on hardened steels have always been a great challenge. Dry machining and two cooling systems were used when tapping hardened AISI H13 (53 HRC). Embedded thermocouples were used for temperature measurement close to the thread diameter in the radial and axial direction. A FEA model was used to evaluate the heat “Q”, and coefficient of convection “h”. The lowest temperature peak occurred with the flooded system, followed by the MQL, and dry condition. The heat and coefficient of convection increased when using the flooded system, followed by the MQL, compared to the dry condition. Those values were also in accordance with early published works, using different techniques.

Analysis of the Forces in Micromilling of Hardened AISI H13 Steel with Different Grain Sizes Using the Taguchi Methodology

The micromachining process has been applied to the free form and micromolds markets. This has occurred due to the growth in demand for microcomponents. However, micromachining of hardened steels is a challenge due to the reduction in tool life and the increase of the surface roughness when compared with the macromachining process. This paper focused on the analysis of micromilling forces on hardened AISI H13 steel with different grain sizes. Experimental tests were carried out on workpieces with different austenitic grain sizes and a hardness of 46 HRC. Micro-end-mill cutters with a diameter of 0.5 mm and (TiAl)N coatings were applied in the milling of workpieces of 11 × 11 mm. The input parameters were two radial depths of cut, two cutting speeds, and two feed rates. The influence of the input parameters on the response cutting force was analyzed using the Taguchi method. Finally, considering the large grain size, the cutting forces in the x-, y-, and z-axes direction were small.

Processing of Threads on a Magnesium Alloy Using a Special Process

Tapping is a complex process largely applied on metal cutting industry. The tapping process can be carried out using cutting or forming tools. This work presents a study of the form tapping process using a tool without cutting edge and helix angle and with external diameter much smaller than the final thread. The experimental tests were carried out with three forming speeds and three helical feed rates to produce M12 threads into the AM60 Magnesium alloy. The results showed that these specfic forming taps provided internal threads with good thread shapes and finishing forms that were as good as the traditional forming tap, which uses tools with the same final thread hole diameter. In addition, the increase of helical feed rate decreases the torque and thrust force, but the differences were greater in torque than in thrust force. The greatest decrease of torque occurred for the lowest forming speed, and the lowest decrease of torque occurred for the highest forming speed. Moreover, the thrust force and torque recorded in the experimental tests were lesser than in traditional form tapping for the same thread area, at least for the magnesiun alloy used.

Influence of Different Cooling Systems on Surface Roughness in the Turning of the Ti-6Al-4V Alloy Used as Biomaterial

Titanium and its alloy are materials with great application in the aeronautic and biomedical area. These applications have grown in the last decade due to high resistance to corrosion and biocompatibility of the Titanium alloys. However, Titanium and its alloys are classified as hard-to-machining materials that increase the production costs due to the highest tool wear. Thus, the finishing of components made of Titanium alloys can be impaired due to the complex shearing mechanism. This work shows a study of the influence of cooling systems and the input parameters on the turning of the Ti-6Al-4V alloy. Two depths of cut, two feed rates, new and worn tools, and three cooling systems were used as input parameters. The response was the surface roughness measured according to the Ra parameter. According to the results, it can be supported that the variation of all input parameters has influence on response. However, the most important input parameter on surface roughness was the feed rate. Thus, it can be concluded that the correct choice of the cutting parameters is relevant to produce high-quality components.

Evaluation of Hole Quality in Hardened Steel with High-Speed Drilling Using Different Cooling Systems

This work evaluates the hole quality on AISI H13 hardened steel using high-speed drilling. Specimens were machined with new and worn out drills with 8.6 mm diameter and (TiAl)N coating. Two levels of cutting speed and three levels of cooling/lubrication systems (flooded, minimum lubrication quantity, and dry) were used. The hole quality is evaluated on surface roughness (Ra) parameter, diameter error, circularity, and cylindricity error. A statistical analysis of the results shows that the cooling/lubrication system significantly affects the hole quality for all measured variables. This analysis indicates that dry machining produces the worst results. Higher cutting speeds not only prove beneficial to diameter error and circularity errors, but also show no significant difference on surface roughness and cylindricity errors. The effects of the interaction between the cooling/lubrication systems, tool wear, and cutting speed indicate that only cylindricity error is influenced. Thus, the conclusion is that the best hole quality is produced with a higher cutting speed using flooded or minimum lubrication quantity independent of drill wear.

Evaluation of Quality of Steering Systems Using the Honing Process and Surface Response Methodology

Gears are components indispensable in power systems, gearboxes, and machine tools. Modern gears have preferably high strength, high hardness, wear resistance, and low weight. According to this characteristics, the manufacturing process of gear generally use undefined cutting edge. Nowadays, honing process has been introduced in Brazil into companies that manufacturing steering systems and gearboxes. Honing has great advantages that are the possibility of adjustment of gearing failures and mixed orientation of the manufacturing of grooves approaching to the pitch diameter. This paper shows an analysis of honing process that includes a modeling of accurate, the Brazilian development status, and mainly the optimization using response surface methodology. Tests were carried out in plant using 54 pinions of 4320-H steel with hardness of core of 295 HV2 and surface hardness of 600 HV2. The machine used in tests was a Fässler model HMX-400. The input parameters were spindle speed of pinion, speed of grinding wheel, feed rate, spark out, and cycle time. The results showed that the cycle time and feed rate influenced directly the helix form error and the evolvent profile error. The re-sults showed not only on the decrease of surface roughness but also on that, the geo-metric errors were below the standard DIN 5.

Design of Experiments—Statistical and Artificial Intelligence Analysis for the Improvement of Machining Processes: A Review

The modern industry needs that its manufacture process to be fast, efficient, low cost, ecologic, and other. It occurs because many consumers require that the products have great quality and a fair price. Furthermore, in sometimes, the industry has the sale price imposes by client. Thus, the industry develops news techniques, process, tools, and other to attain this goal. However, these new developments require great studies to obtain the best condition and avoid that become more a waste. The Statistical or Artificial Intelligence (AI) Analysis are great ways to understand the new developments and obtain the best conditions. This review chapter presents the techniques (Statistical and AI) that were applied to plan and analyse the machining processes. Aim of this chapter is to argue the planning and analysis importance in researches, as well as help researchers to choose a technique and define their machining experiments, optimising the time, material and other means.

Finite Element Method in Machining Processes: A Review

An ecological production and low cost is the target of several industries. Increasingly, the product development is critical stage to obtain a great quality and fair price. This stage will define shapes and parameters that will able to reduce wastes and improve the product. However, the expense of prototypes also should be reduced, because, in general, the prototypes are more expensive that final product. The use of finite element method (FEM) can avoid much tests that reduce number of prototypes, and consequently the project cost. In the machining processes simulation, several cutting conditions can be reproduced to define the best tool and parameters in function of analyzed forces, stress, damages and others. This paper debates the use of FEM in the machining processes, shows some researches and indicates the main attributes to develop simulation studies for conventional machining and micromachining.

Materiais compósitos particulados em matriz epóxi reforçados com serragem, cimento e silicato de magnésio

Este trabalho tem como objetivo investigar propriedades fisicas (densidade volumetrica e absorcao de agua) e mecânicas (modulo de elasticidade e resistencia a compressao) de materiais compositos particulados em matriz epoxi reforcados com serragem de madeira, cimento Portland e silicato de magnesio. Um planejamento experimental inicial foi elaborado envolvendo apenas a resina epoxi e a serragem de madeira. Posteriormente, elegeu-se o tratamento que forneceu os maiores valores para o modulo de elasticidade na compressao. Sobre a condicao escolhida, foram desenvolvidas outras quatro, incorporando-se 10% e 20% em fracoes massicas de particulas de silicato de magnesio e cimento Portland sobre a resina. Os compostos com 30% de serragem de madeira Eucalyptus grandis e faixa granulometrica 50-80 US-Tyler apresentaram os melhores valores para o modulo de elasticidade na compressao, sendo utilizados como condicao de referencia para a inclusao das particulas de cimento e do talco. O emprego do cimento nos compostos conferiu aumentos significativos no modulo de elasticidade a compressao, densidade e reducao na absorcao de agua. O mesmo nao ocorreu com a incorporacao de particulas de silicato de magnesio, a qual foi significativa apenas na absorcao de agua, sendo os maiores valores provenientes dos materiais fabricados com a adicao de 20%.