Pradeep Kumar Jha

The Key Attributes of Synthesizing Ceramic Particulate Reinforced Al-Based Matrix Composites through Stir Casting Process: A Review

It is apparent that technological development depends on advances in the field of materials. One may design most durable and highly efficient automobile or aircraft; however, without appropriate materials to fulfill the design requirements, the product may not be realistic. Therefore, to enhance the performance of engineering materials in line with technological development, engineers and scientists are always striving to improve existing materials or to produce new materials. Metal Matrix Composites (MMCs) are example of such newly emerging engineering materials. However, MMCs are more expensive than their competitors. Cost is the key factor for their wider application in modern industry. Cost reductions can be achieved by cheaper reinforcements, simpler fabrication methods, and higher production volume. Refractory particles are relatively cheaper and easily available reinforcements. Particulate reinforced MMCs are economically processed through the stir casting route. However, in stir casting process, there are lots of processing challenges, such as undesirable interfacial reactions, porosity, uneven distribution, agglomeration, engulfment, and poor wettability. The purpose of this review is therefore to provide a reliable scientific basis for the researchers planning to synthesize particulate reinforced MMC in stir casting route.

Effect of Sliding Distance, Applied Load, and Weight Percentage of Reinforcement on the Abrasive Wear Properties of In Situ Synthesized Al–12%Si/TiC Composites

This study investigated the effect of applied load, sliding distance, and weight percentage of reinforcement on the abrasive wear characteristics of in situ synthesised Al-12Si/TiC composites using a pin-on-disk machine. The strength, hardness, and percentage porosity were also investigated. Scanning electron microscopy (SEM) was utilized to study the microstructure and wear surface behavior of the experimental materials. The results revealed that the strength and hardness increased with increasing weight percentage of reinforcement. However, the percentage porosity was relatively high in the higher weight percentage of reinforcement. The weight loss and coefficient of friction increased with increasing applied load and sliding distance. In contrast, the weight loss and coefficient of friction decreased when the weight percentage of TiC increased. Wear debris in the form of fine black powder and small grooves were noticed in the SEM micrograph of the abraded surfaces of all tested materials.

A review of rapid prototyping integrated investment casting processes

Investment casting is competitive with all other casting processes where the size of the product is within a mutually castable range. Though investment casting is used to produce metal parts of any intricate shapes with excellent surface finish, it suffers from long lead time and high tooling costs, which makes it uneconomical for the production of either single casting, or small and medium production units. These problems could be overcome by the applications of rapid prototyping and rapid tooling technologies for low-volume investment casting production runs. The present article analyzes different classifications of rapid prototyping techniques and it reviews various investigations made on the usability of rapid prototyping- and rapid tooling-integrated investment casting process, with their advantages and limitations. The emerging areas of applications of rapid prototyping like dentistry, jewelry, surgical implants, turbine blades, etc., are accordingly discussed. Further, an elaborate discussion is made on the application of newer technologies for directly developing ceramic shells. This article also emphasizes on various future scopes possible in rapid prototyping-integrated investment casting process.

Modelling and predicting the effects of submerged arc weldment process parameters on weldment characteristics and shape profiles

The submerged arc weldment cross section shape profiles indicate the macrostructure zones’ boundaries of both the base metal and weld that are affected by the weld thermal cycle. These macrostructure zones are broadly designated as the weld reinforcement, penetration and heat affected zones. The present investigation is aimed at predicting the shape profiles and characteristics of the submerged arc weldment zones based on statistical analysis. A full factorial design matrix was used for the submerged arc weldment butt-bead-on plate welds to study the effects of welding input variables. The outputs from the welding, such as the weld macrostructure characteristics, were mathematically modelled with respect to the input process variables. The interaction effects of the welding input process variables on the responses were also investigated. Based on the weldment characteristics, including that of the bead contact angle, a mapping technique was developed for the graphical representation of the macrostructure zones’ shape profiles. The modelling approach adopted in the present investigation can be used to predict the fusion and heat affected zone shape profiles of submerged arc-based repair welds and claddings.

Abrasive Wear Behavior of In Situ TiC Reinforced with Al-4.5%Cu Matrix

The present work deals with the investigation on weight loss and coefficient of friction of TiC reinforced Al-4.5%Cu in situ metal matrix composites. Experiments were conducted using pin-on-disc apparatus against abrasive paper by varying the applied load, sliding distance, and weight percentage of TiC. The results indicated significant improvement in the mechanical properties and wear resistance of experimental composites as compared to the parent metal matrix. The percentage of porosity though increased with increasing TiC reinforcement. The variation of weight loss of composites increased linearly with increasing applied load and sliding distance, whereas decreased with increasing weight percentage of TiC reinforcement. The coefficient of friction decreased linearly with increasing applied load and TiC reinforcement. SEM micrographs of worn surfaces show a well compacted transfer layer of wear debris along with wear track over the sliding surface. Grooves, delamination, and crack propagation were also observed in all test samples. The effective depth of penetration and size of debris was seen to reduce with increasing wt.% of TiC reinforcement in metal matrix.

Optimization and Prediction of Angular Distortion and Weldment Characteristics of TIG Square Butt Joints

Abstract Autogenous arc welds with minimum upper weld bead depression and lower weld bead bulging are desired as such welds do not require a second welding pass for filling up the upper bead depressions (UBDs) and characterized with minimum angular distortion. The present paper describes optimization and prediction of angular distortion and weldment characteristics such as upper weld bead depression and lower weld bead bulging of TIG-welded structural steel square butt joints. Full factorial design of experiment was utilized for selecting the combinations of welding process parameter to produce the square butts. A mathematical model was developed to establish the relationship between TIG welding process parameters and responses such as upper bead width, lower bead width, UBD, lower bead height (bulging), weld cross-sectional area, and angular distortions. The optimal welding condition to minimize UBD and lower bead bulging of the TIG butt joints was identified.

Parametric optimization of the investment casting process using utility concept and Taguchi method

Investment casting process, also known as lost wax process, is utilized when complex detail, undercuts or non-machinable features and accurate parts are desired. It begins with a wax pattern which is an exact replica of the as cast part. So the properties of the wax patterns are ultimately passed on to the castings. This article highlights the application of utility concept with Taguchi method for the multi-response optimization of wax patterns made by the investment casting process. The wax injection process parameters considered are injection temperature, injection pressure and injection time, whereas the responses are linear shrinkage, surface roughness and penetration, respectively. The experiments are planned as per Taguchi’s L9 orthogonal array. The utility concept converts multi-response optimization problem into single response optimization problem and thereafter Taguchi method is applied. The results indicate that injection pressure is the most significant process parameter influencing the quality characteristic of the wax patterns. The confirmation tests with optimal levels of injection process parameters are carried out to illustrate the efficacy of the proposed method. The results are found to be within the confidence interval. The optimization results revealed that a combination of lower level of injection temperature and injection time along with higher level of injection pressure leads to overall improvement in the quality of the wax patterns. It has also been established that there is some quality loss in terms of surface finish of the wax patterns in multi-response optimization as compared to single response optimization, though an overall improvement in the process is being observed.

Modeling and parametric optimization of investment casting process by uniting desirability function approach and fuzzy logic

Investment casting is accepted worldwide on the basis of the superior quality of the castings being produced in terms of high dimensional accuracy and surface finish. It usually employs disposable wax patterns and the quality of the wax patterns are reflected in the investment cast product. Keeping this in mind, integration of desirability function approach and fuzzy logic for the multi-response optimization of wax patterns made by the investment casting process has been conceptualized in the present study. The aforementioned method overcomes the limitation of the desirability function approach for multi-response optimization problems. The responses, linear shrinkage and surface roughness have been considered for simultaneous optimization. The input parameters considered are injection temperature, injection pressure and die temperature. A fuzzy model has been developed with desirability values of responses as inputs and multi-performance index MPI as output. The optimal levels of the process parameters are determined through the analysis of means of the MPIs. Confirmatory experiments are conducted to verify the optimal settings. The proposed method may be practically employed by the investment casters around the globe to increase the overall efficiency of the process and product.

Optimization of multiple responses in the lost wax process using Taguchi method and grey relational analysis

Investment casting process is one of the most versatile and flexible process which produces near net-shape metal components. The disposable pattern employed in the process is generally made up of wax blend, whose accuracy has a direct effect on the accuracy achievable in the final cast part. This article addresses an approach based on Taguchi method in integration with grey relational analysis for multi-response optimization of wax patterns made by the investment casting process. The experiments are planned using Taguchi’s L18 orthogonal array. The responses considered in this study are linear shrinkage, surface roughness and penetration, respectively. A grey relational grade obtained from grey relational analysis is used to determine the optimal process parameters. The significance of the process parameters on overall quality characteristics of the wax patterns has been evaluated quantitatively by the analysis of variance method. Optimal results have been verified through confirmation experiments, which indicate that the multi-performance characteristics of the wax patterns can be improved effectively through this approach. It was also found that though high injection temperature increases the surface finish of the wax blends, it adversely affects the mechanical properties of the wax blends.

Influence of injection process parameters on dimensional stability of wax patterns made by the lost wax process using Taguchi approach

Investment casting is a manufacturing technique employed to produce near net shape metal components. Wax is the most widely used pattern material. In the present work, the wax blend, to be used in the investment casting process, is prepared by mixing different waxes and starch as filler material to reduce the shrinkage of wax patterns. The effect of the selected injection process parameters on the dimensional stability of the wax patterns made by the investment casting process using silicon rubber mould has been studied and the optimum injection process parameters to reduce the shrinkage of wax patterns have been suggested. The wax injection processing parameters considered for experimentation were injection temperature, injection pressure and injection time. Taguchis L9 orthogonal array was used for designing the experiments. The signal-to-noise and the analysis of variance were used to find the optimum levels and to indicate the impact of the process parameters on shrinkage of wax patterns. The confirmation tests were conducted and the results were found to be within the confidence interval. The analysis of experimental results showed that the injection temperature and injection pressure greatly influenced the dimensional stability of wax patterns.