Marcelo Araújo Câmara

Motor test benches require torque and speed measurement instruments alongside a loading system to characterize performance. However, Technology Readiness Level 4 (TRL4) motors often feature custom geometries, leading to costly adaptations of standard equipment. This paper introduces the Servomotor Torque Measurement System (STMS), an integrated solution that measures torque under rotation. The STMS combines a servomotor (SM), its servo drive, and a programmable logic controller (PLC). It repurposes a single SM to replace three conventional bench components: the torque transducer, speed sensor, and primary load unit. Operating in torque control mode with a speed setpoint of ω SP = 0 rpm, the system applies a controlled load via the torque setpoint while simultaneously acquiring torque and speed data directly from the motor shaft. This eliminates the need for multiple instruments and inline mechanical couplings. The SM acts as a load generator, applying a counteracting torque without affecting the rotational speed, which is also acquired via the PLC. As the SM torque is internally calculated by the drive, the STMS was calibrated for two ranges (0–1.000 N·m and 0–9.00 N·m) using different motor models, following the Brazilian standard NBR 12240. Results showed measurement uncertainties between 0.6% and 0.8% of full scale. The system’s practicality was demonstrated by testing a TRL4 thermomagnetic motor, confirming its feasibility for potential dynamic torque measurement applications.

Objective: This study aims to investigate the tribological behavior of MnSi alloy steel coatings subjected to three heat treatments (normalizing, deep quenching, and surface quenching) under dry contact conditions and in the presence of lubricant. Theoretical Framework: This work is based mainly on the foundations of Callister and Shackelford materials, and on the research on tribology by Hutchings, Rabinovicz and Astakhov. Method: After coating deposition by gas arc welding, followed by face milling and heat treatment, the samples were finished to achieve two different levels of surface roughness (Ra = 0.8 µm and Ra = 0.2 µm). Microhardness measurements were performed, as well as dry and lubricated pin-and-disc wear tests. Results and Discussion: Microhardness measurements were performed, as well as dry and lubricated pin-and-disc wear tests. The results indicated that the surface quenched coating presented the best overall performance (higher hardness and lower wear rate). Research Implications: The results can be applied to surface engineering. These implications may include mining; civil construction; and land, sea, and air transportation. Originality/Value: This study contributes to the literature by addressing heat treatment techniques for increasing wear resistance, thus extending the longevity of parts in friction service. The relevance and value of this research are demonstrated by its direct impact on the use of scarce and non-renewable mineral resources and its reduction in energy demand, as it increases the time between maintenance shutdowns and subsequent shutdowns.

O comportamento da superfície de materiais de engenharia exerce um grande papel em diversas áreas da tecnologia moderna. Assim, conhecer as propriedades e características de superfícies de engenharia é de extrema importância. Uma dessas propriedades é a dureza ao riscamento e uma das principais maneiras de se obtê-la é por meio de ensaios de riscamento. Neste trabalho foi investigada uma nova abordagem de ensaio de riscamento desenvolvido em um centro de usinagem com trajetória do indentador em rampa. Amostras de aço inoxidável austenítico AISI 304 com diferentes processamentos (fresamento e roleteamento) foram utilizadas como corpos de prova e um dressador de ponta única de diamante foi usado como indentador. Os resultados mostraram que a técnica é promissora, visto que os diferentes valores de rugosidade e dureza entre as amostras ensaiadas influenciaram os resultados de dureza ao riscamento e de coeficiente de atrito. Ademais, este tipo de ensaio pode ser uma alternativa na investigação da espessura mínima de corte.

This article aims to investigate the influence of different contact conditions on the friction properties of an Nb-stabilized AISI 430 ferritic stainless-steel sheet with deep drawing quality. Three tribological tests were performed: pin-on-disk, bending under tension, and strip-tension test. Moreover, counter samples of a hard metal (WC-12%Co) with surface finishes of 0.27 and 0.54 μm were used in the friction tests under dry and lubricated conditions. The influence of the texture and relative elongation of the strip on formability also were investigated. A comparative analysis of the results revealed that the coefficients of friction, wear, lubricant efficiency, and hardness measured below the wear surface indicated a strong dependence on surface roughness and the friction test type. The coefficients of friction obtained from the pin-on-disk test were higher than those obtained from the formability tests. In addition, the coefficient of friction increased with increasing relative elongation during the formability tests; it was higher in the bending-under-tension test than in the strip-tension test, mainly owing to the increasing strip surface roughness. The contact pressure during the formability tests was non-uniform during strip sliding under the tool. According to our results, for each friction condition in a specific area of the forming die, there is a value of the coefficient of friction, depending on the kinematic conditions. Therefore, the results can be used as input data to define design guidelines, improve productivity, and improve product quality from this steel sheet.

RESUMO O atrito nas interfaces ferramenta/cavaco e ferramenta/peça é complexo dificultando a determinação do coeficiente de atrito nos processos de usinagem. Assim, vários ensaios tribológicos foram desenvolvidos para simular as condições de corte e determinar o coeficiente de atrito. Este trabalho apresentou análise comparativa do coeficiente de atrito entre o aço ABNT 1045 e WC-10Co revestido com AlCrN por meio de dois métodos: ensaio de torneamento e ensaio de compressão de anel à quente. O ensaio de torneamento foi realizado com corte oblíquo nas velocidades de corte 150 e 220 m/min. A aquisição dos sinais das componentes de força da usinagem por meio de um dinamômetro. O ensaio de compressão de anel foi realizado nas temperaturas de 200 e 400 °C. Os coeficientes de atrito foram obtidos por meio de modelos matemáticos. A análise estatística do coeficiente de atrito apontou equivalência do coeficiente de atrito no ensaio de torneamento na velocidade de corte 150 m/min com o ensaio de compressão de anel à quente 200 °C. Assim como no ensaio de torneamento na velocidade de corte 220 m/min com o ensaio de compressão de anel à quente 400 °C. A análise macrográfica do anel após a deformação no ensaio de compressão de anel observou a influência da temperatura de ensaio no deslocamento do raio neutro. A análise superficial dos anéis e das matrizes do ensaio de compressão foi realizada por meio de microscopia óptica (MO) e rugosidade Ra, onde observou-se o aumento da rugosidade após o ensaio e a presença de desgaste abrasivo.

This work presents an experimental–numerical approach aimed at determining the chip–tool contact length during orthogonal cutting of annealed AISI 4340 steel (223 HV) with TiN-coated tungsten carbide inserts. Initially, pin-on-disc tests were performed, followed by orthogonal cutting tests. The components of the cutting force were used to calculate the coefficient of friction in orthogonal cutting, and its value was compared with those obtained under sliding. Moreover, the cutting force components obtained experimentally were used to assess the reliability of the finite element model and estimate the temperature in the cutting zone. The contact length between chip and rake face was calculated based on the experimental feed force and shear strength of the work material and was compared with the results provided by an analytical model. The experimental–numerical approach can be considered more accurate due to the fact that it considers the effect of the tool–chip interface temperature on the shear strength of the work material. However, the analytical model is quite straightforward, since it only requires the values of chip thickness and undeformed chip thickness to estimate the tool–chip contact length.