Applied Mechanics and Materials Vols. 799-800

Abstract: Support structure plays a vital role in Rapid Prototyping system in producing quality and dimensional accurate prints for a product having bridges or overhangs in a Rapid Prototyping product. The paper reports the selection of best support structure for any given model based on build time, material requirement and quality output of the prints. It also discusses the effects of introducing raft layers on a given model. A CAD model in STL (stereo lithography) format is an input to the Rapid Prototyping system. The CAD data is sliced for 3 different support structures by keeping constant printing parameters. Based on the build time, material consumption and part quality obtained, thebest support structure of any given model is experimentally found.

Abstract: The development of complex component assemblies from non-orthogonally oriented panels is laborious with currently available methods. The reason for this is the lack of integrated solutions in planning, fabrication and assembly. Thus, applications in architectural design are mostly restricted to geometrically simple, orthogonal shapes. We present a novel dovetail joining method that aims at facilitating the realization of polyhedral structures. Dovetail elements as well as panels may be fabricated using CNC water jet cutting technology. Compared with conventional processes, the presented method adopts the potential of industrial fabrication strategies and by that increases the reliability of respective processes while decreasing cost synchronously.

Abstract: Wire Electric Discharge Machining (WEDM) is a non-traditional process of material from conductive material to produce parts with intricate shape and profiles. In the present work, an attempt has been made to optimization the machining conditions for maximum material removal rate, minimise kerf width based on (L₉ Orthogonal Array) Taguchi method. Experiments, based on Taguchi’s parameters design, were carried out to effect of machining parameters, like pulse-on-time (T_ON), pulse-off-time (T_OFF), peak current (I_P), and wire feed (W_F) on the material removal rate and kerf width. The importance of the cutting parameters on the cutting performance outputs is determined by using the variance analysis (ANOVA). The variation of MRR and kerf width with cutting parameters is modeled by using a regression analysis method.

Abstract: The computer model that allows predicting the temperature distribution during local ion nitriding with hollow cathode effect (HCE) and depth of the diffusion zone after the treatment was developed. The influence of the HCE on the temperature distribution for the gear was studied. Investigation results of the hollow cathode effect influence on the hardened layer depth for a sample of 38KhMYuA steel are presented.

Abstract: The reaming deals with cutting and burnishing simultaneously and needs a severe cutting performance. The cutting mechanism is so complicated that the method of evaluating the effect of the cutting fluids on the finished surface integrity is not easy. In this study, the examination was carried out to extract an optimum cutting fluid in Incoloy 825reaming. That is, instead of reaming, the simple method was established to experimentally investigate the effect of the cutting fluids on the finished surface integrity, such as the maximum height and dimensional errors. This method is applicable to reaming processes supported by devising the tool geometry and the cutting conditions in facing with the lathe. As a result, it was clarified that the synthetic soluble showed good performance for the finished surface integrity and this simple method was effective for the evaluation of the optimum cutting fluids in Incoloy 825 reaming.

Abstract: In machining operation of mould cavities, the tool travels in various straight and corner profiles following predetermined toolpath. Such condition results in a fluctuation of cutting forces that may produce bad surface finish. The objective of this study is to investigate the most influential parameters on cutting operation for both straight and corner profiles of pocketing operation. Cutting speeds of 150, 200 and 250m/min, feedrates from 0.05, 0.1, 0.15 mm/tooth and depths of cut of 0.1, 0.15 and 0.2 mm were selected for the cutting processes. Taguchi L9 orthogonal array with Pareto ANOVA analysis was employed to analyze the effects of the selected parameters. The result demonstrates there are different effects of cutting parameters on cutting forces for straight and corner profiles. Furthermore, it was found that cutting speed and feedrate are prevailing factors that affected cutting forces for both types of profile.

Abstract: The roundness is one of the most important criteria to accept the mechanical parts in the CNC turning process. The relations of the roundness, the cutting conditions and the cutting forces in CNC turning is hence studied in this research. The dynamometer is installed on the turret of the CNC turning machine to measure the in-process cutting force signals. The cutting parameters are investigated to analyze the effects of them on the roundness which are the cutting speed, the feed rate, the depth of cut, the tool nose radius and the rake angle. The experimentally obtained results showed that the better roundness is obtained with an increase in cutting speed, tool nose radius and rake angle. The relation between the cutting parameters and the roundness can be explained by the in-process cutting forces. It is understood that the roundness can be monitored by using the in-process cutting forces.

Abstract: Porosity is a major problem occurring in aluminium alloy casting. During the process of solidification, alloy would shrink and emit dissolving hydrogen causing porosity formation inside the solidified part which leads to mechanical properties degradation. This research aims to produce a formula to explain the resulting porosity with the initial chemical compositions and cooling rate. A mathematic model is, at first, inferred from previous researches to be a template function. Differential Evolution is utilized to generate inner polynomial parts and to find appropriate coefficients to experimental data obtained from other publications. The optimized function promisingly shows good fit to the problem domain demonstrating that the resulting function is an efficient model to explain porosity formation behaviour.

Abstract: Quality of a weld produced is generally evaluated by different parameters such as weld size, bead geometry, deposition rate, hardness and strength. A common problem that has been faced at the construction sites is to obtain a good welded joint having the required strength with minimal detrimental residual stresses to avoid any premature cracking due to high variation of hardness. In order to address this issue and to attain good weld quality, this study has been made to comprehend the effect of the post weld heat treatment on P91 material welds produced by TIG welding. Findings from the studies indicate that the PWHT has significant influence on the weld hardness of Alloy Steel-A335 P91 pipes. It is eminent that during cooling, after welding of P91, quenched martensite was formed in the HAZ that results in an increased hardness to an undesirable level of more than 250HB. PWHT at temperature of 760°C for 2 hours has good influence on mechanical properties as the hardness decreases and turns out to be uniformly distributed. If the PWHT is correctly carried out, the hardness of parent metals, heat affected zones and weld metal can be brought into the required limits to avoid any premature cracking due to high variation of hardness.

Abstract: Latest research clearly demonstrates the excellent capability of the gear power skiving technology. For further improvement of the skiving process and enhancement of the process reliability the fundamental research on the cutting mechanism of cylindrical gear power skiving was conducted. First the kinematic model of power skiving and mathematical equations of cutter were established according to the engagement principle of crossed helical gears. Then, based on the proposed model, we investigated the simulation process, chip deformation mechanism and the cutter top relief angle. The results support the skiving cutter design and process optimization and are an important basis for the implementation of the advanced gear process.