Innovative Mechanical Engineering

INVESTIGATION OF HOT FORGING PROCESS BY FEM SIMULATION

Saša Ranđelović — 2024-10-03

The process of hot forging of steel is one of the most common industrial technologies. Designing this technology is a challenge because today complex geometries of finished products are obtained. The goal of FEM simulation is to generate the most realistic contact between the tool and the deformable material, both in volume and in the immediate vicinity of the boundary surfaces of the tool. FEM simulation by Qformof the hot forging process is a good way to prevent possible errors and problems of tool construction. Using the example of a complex forging, the paper analyzes the geometrical conditions of contact, the stress-deformation state within the deformable volume, and the constructive solution of the tool for hot forging in a closed die.

IMPROVING PRODUCTION EFFICIENCY AND QUALITY IN AN ALUMINUM PROCESSING COMPANY THROUGH LEAN PRACTICES

Milena Rajic — 2024-10-03

This paper analyzes the application of Lean methodologies to improve the efficiency and quality of production in the aluminum foundry MTC "Nissal." The enterprise specializes in the manufacturing, refining, and shaping of aluminum and its alloys. It operates via two primary divisions: profile extrusion and aluminum rod manufacture. The main findings indicate a 14% decrease in production time mostly caused by equipment failures, and a significant rate of faults, with 71% of the defects being attributable to operator irresponsibility.By implementing Lean methods such as the 5S methodology and Statistical Process Control (SPC), the analyses showed areas that may be improved. The 5S audit revealed workplace organization and cleanliness, with an average score of 1.73 out of 5. The 5S shine phase had the lowest score of 1.38. The SPCanalysis conducted on the manufacture of billets in EN AW 2011 alloy revealed a process capability index (Cp) of 1.154 and a process capability performance index (Cpk) of 1.015. These values indicate that the process is incapable and exhibits some inconsistency.By implementing Lean techniques, the enterprise aims to decrease downtime, minimize defects, and improve overall production efficiency and quality. This will help establish MTC "Nissal" as a strong competitor in the aluminum market.

DEVELOPMENT AND CORROSION RESISTANCE PERFORMANCE OF GREEN AUTOMOTIVE BRAKE PADS DEVELOPED FROM THE WASTE SHELLS OF GIANT AFRICAN SNAILS

Martins Obaseki — 2024-08-27

In this study, morphological and corrosion analyses (Fourier transform infrared spectroscopy, scanning electron microscopy, and electrochemical tests) were used to investigate the properties of newly developed, non-toxic organic brake pads. The green automotive brake pads were developed from waste giant African snail shell as reinforcement materials. Also, Fourier transform infrared spectroscopy (FTIR) was used to determine the functional group of the developed brake pad samples. The developed brake pad corrosion resistance was studied using open circuit potential (OCP), Potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Additionally, scanning electron microscopy (SEM) was used to examine the surface morphology of the developed green brake pad. The findings revealed that the developed brake pad with a 75-grain size exhibited optimal corrosion resistance when compared to the control, 40µm and 90µm, samples. SEM analysis revealed enhanced interfacial bonding between the binder and snail shell particles as the grain size decreased, attributed to improved bonding and reduced inter-packing distance with decreasing sieve grade. The existence of corrosion debris was more evident on the deformed surface of the control sample compared to the developed brake pad samples. The study showed that the brake pad developed from snail shells has better morphological and corrosion resistance performance than the control sample brake pads and can be applied in heavy-duty vehicles.

NUMERICAL SIMULATION OF MHD NANOFLUID FORCED CONVECTION HEAT TRANSFER IN A RECTANGULAR ENCLOSURE WITH VARIABLE PARAMETERSTERS

Ehsan Kianpour — 2024-10-03

This numerical research examines the cooling of a hot obstacle within a rectangular cavity containing water-copper oxide nanofluid. This cavity has an inlet and outlet, and the cold nanofluid comes from the left side of the cavity and goes out from the opposite side, after cooling the hot obstacle. All walls of the cavity are insulated and the SIMPLER algorithm is employed for solving the governing equations. The effect of different parameters such as nanoparticle volume fraction, Reynolds number, and Hartmann number is investigated. The results show that with an increase in the Reynolds number, the isothermal lines become more compact and the dimensions of the cold zone near the inlet increase. This phenomenon causes the isothermal lines to be closer to the hot barrier and the temperature gradient, and as a result the heat transfer of the hot barrier increases.

NONLINEAR DYNAMICS OF BALL ROLLING OF RADIAL BEARINGS IN AN ASSEMBLY VITH AN UNBALANCED MULTI-STAGE ROTOR

Katica (Stevanovic) Hedrih — 2024-10-03

The paper presents a mathematical analysis of the kinematics and dynamics of rolling balls of an ideal radial ball bearing assembly of eight or twelve balls, between the stationary circular groove and the movable one mounted on the shaft, which rotates at the appropriate angular velocity. Ordinary non-linear differential equations and equations of phase trajectories of the assembly were derived for two cases: a) when the eccentricity of the center of mass of one or more pairs of radial bearing balls occurs in the rolling bearing and when the rotor is balanced; and b) when the non-linear dynamics of the rolling of the ball bearings occurs in the rolling bearing caused by the non-linear dynamics of an unbalanced, single-stage or multi-stage rotor.