Rukiye Ertan

Experimental investigation of FDM process for improvement of mechanical properties and production cost

Purpose – The mechanical properties and surface finish of functional parts are important consideration in rapid prototyping, and the selection of proper parameters is essential to improve manufacturing solutions. The purpose of this paper is to describe how parts manufactured by fused deposition modelling (FDM), with different part orientations and raster angles, were examined experimentally and evaluated to achieve the desired properties of the parts while shortening the manufacturing times due to maintenance costs. Design/methodology/approach – For this purpose, five different raster angles (0°, 30°, 45°, 60° and 90°) for three part orientations (horizontal, vertical and perpendicular) have been manufactured by the FDM method and tested for surface roughness, tensile strength and flexural strength. Also, behaviour of the mechanical properties was clarified with scanning electron microscopy images of fracture surfaces. Findings – The research results suggest that the orientation has a more significant in...

Influence of Heat Treatment Parameters on the Microstructure and Mechanical Properties of Boron-Alloyed Steels

Abstract This paper focuses on the effect of heat treatment parameters on the microstructure and mechanical properties of quenchable 22MnB5 steel sheets with an Al–Si layer. Heat treatment parameters such as temperature and cooling rate from the solid solution temperature were investigated. For this purpose, the heat treatment was conducted within the temperature range from 700°C to 950°C, and two different cooling techniques were applied to the specimens: air cooling and water quenching. The microstructures of the specimens were then studied using optical microscopy. Additionally, tensile and hardness tests were performed at room temperature. The results show that the effects of heat treatment were obviously influenced by the original microstructure of the 22MnB5 sheet. With the increase of heat treatment temperature, the martensite proportions increased, and the hardness and tensile strength also increased, especially after the 850°C quenching. Moreover, quenching after 900°C has been reached was determined to be an ideal process for hot forming 22MnB5 steel sheets.

The effects of graphite, coke and ZnS on the tribological and surface characteristics of automotive brake friction materials

Purpose – The purpose of this paper is to investigate the role of solid lubricants (graphite, coke, ZnS) on brake performance.Design/methodology/approach – In this study, the tribological and surface characteristic of non‐asbestos organic type brake friction materials containing three different solid lubricants (graphite, coke, and ZnS) in different proportions were examined and evaluated experimentally. The coefficient of friction (COF) and wear behavior of the samples were tested on a chase‐type friction tester, and particular emphases were given to the effect of temperature and number of braking cycles on the COF. Each of the lubricants was added to the mixtures in different amounts and seven different brake linings were manufactured, provided that the total amount of solid lubricants and other ingredients were not changed. The worn surfaces of the specimens were analyzed using a scanning electron microscope with energy‐dispersive X‐ray microanalysis.Findings – The experimental results indicate that gr...

Experimental study on the flexural properties of 3D integrated woven spacer composites at room and subzero temperatures

The flexural behavior of the 3D integrated woven spacer composites with carbon fiber-reinforced polymer face sheets are performed with epoxy and polyester matrix in the warp direction. The static loading of foam core carbon/epoxy and carbon/polyester composite sandwich panels in three-point flexural test was characterized at room temperature (23℃) and at liquid nitrogen temperature (−40℃). Macro-fracture morphology and progress have been examined to understand the deformation and failure mechanism. Significant increases in the flexural strength with brittle type core shear failure were observed at low temperatures as compared with the corresponding room temperature behavior. The performance of the epoxy-based composite is compared to the polyester one. Significant changes in the flexural properties of the composites have been found, first related to the temperature and then to the resin type. The flexural properties of the epoxy-based composites were affected greatly by temperature and exhibited higher flexural performance than polyester-based composites at low temperatures.

Optimisation of brake friction material on tribological characteristics and cost using constrained mixture design method

In the present paper, the effect of ingredients proportion was investigated in terms of tribological performance and cost in a brake friction material. The simplex-centroid design method, a constrained mixture design, was used to manufacture friction materials with different relative amounts of the ingredients. The friction tests were carried out using Chase-type friction tester. The effect of the proportions was obtained in the quadratic model of a three-variable case on the ternary diagrams. Optimum proportions of the ingredients with the highest tribological properties and the lowest cost were determined by comparing response values with boundary conditions on each optimisation circle.

Effect of Plasma Nitriding Parameters on the Wear Behaviour of AISI D6 Tool Steel

Abstract In the present investigation, the effects of plasma nitriding pressure and time on the structural and tribological characterization of AISI D6 grade cold work tool steel were studied. DC glow discharge plasma nitriding process under NH3 gas was performed at temperatures of 500 °C and at pressures of 150 Pa, 450 Pa and 800 Pa for durations of 2 h, 7 h and 10 h. The mass loss and the coefficient of friction were measured using a ball-on-disc wear test with 1.668 N, 4.143 N, and 9.113 N test loads. Cross-section and surface characterizations were evaluated using optical microscopy, SEM, and microhardness test techniques. The surface microhardness was found to increase with the nitriding time and the pressure. The wear resistance of the specimen strongly depends on the nitriding parameters and the applied test load in determining whether a plastic deformation of the surface layer has occurred or not.

Effects of Welding Parameters on the Mechanical Properties of Inert Gas Welded 6063 Aluminum Alloys

Abstract The influence of welding parameters, namely welding current and gas flow rate, on the mechanical properties of Gas Tungsten Arc Welding (GTAW) and Shielded Metal Arc Welding (SMAW) welded 6063 Aluminum alloy (AA 6063) has been investigated. In order to study the effect of the welding current and gas flow rate, microstructural examination, hardness measurements and room temperature tensile tests have been carried out. The experimental results show that the mechanical properties of GTAW welded joints have better mechanical properties than those of SMAW welded joints. Increasing the welding current appeared to have a beneficial effect on the mechanical properties. However, either increasing or decreasing the gas flow rate resulted in a decrease of hardness and tensile strength. It was also found that, the highest strength was obtained in GTAW welded samples at 220 A and 15 l/min gas flow rate.