This paper mainly focuses on parametric optimization of squeeze cast hybrid (LM24-SiC p-coconut shell ash) composite through Taguchi method and genetic algorithm. The composite samples have been cast through squeeze casting for each experimental trial based on L 9 (3) 4 orthogonal array. From analysis of variance, it has been found that reinforcement and squeeze pressure were the casting parameters making significant improvement in the impact strength. A mathematical model representing the process was developed using nonlinear regression analysis. The optimum casting conditions were obtained through Taguchi method and genetic algorithm and checked through the confirmation experiments. In this study, it was confirmed that the castings obtained for the optimum squeeze casting conditions exhibited nearly 20% improvement in impact strength compared to the gravity die casting condition.

Squeeze casting is one of the simplest processes of manufacturing of composite materials and it attains higher advantages of low material processing cost, easy handling of material, size, design and good stability of matrix structure. LM24 aluminium alloy reinforced with silicon carbide (SiC) and coconut shell ash (CSA) were used to prepare the composite. LM24 alloy had wide engineering applications, wherein the addition of SiC enhances the wear resistance and CSA particles offer significant technical and economic benefits. In the present study, the composite samples were prepared based on Taguchi experimental conditions L16 (4-levels and 5- parameters) through squeeze casting method. From the experimental results, percentage of reinforcement and squeeze pressure were most influential parameters on impact strength. The optimum casting condition was obtained by using Taguchi optimization. From microstructural study, applying high level of squeeze pressure improved the uniform dispersion, good bonding between the matrix and reinforcement. Also, 25% of impact strength was improved the composite using Taguchi optimum conditions compared than conventional alloys. Higher squeeze pressure seen to have refined dendritic structure with uniform distribution of reinforcement materials in the aluminium matrix.

In any machining process, the vital part is determination of the optimum values for the process parameters to attain the highest desired quality at a low machining cost. This paper mainly focuses on the surface-roughness optimization in the turning of a hybrid aluminium-matrix (LM24-SiCp-coconut shell ash) composite through the Taguchi method and a genetic algorithm. All composite samples for the study were prepared under the optimal squeeze-casting conditions and experimental trials were selected based on the L9 (3) 4 orthogonal array. The main response considered in this study related to the surface roughness, and machining parameters such as the cutting speed, feed rate, depth of cut and tool-nose radius were taken into consideration. The surface roughness was tested on the composites turned with a high-speed CNC lathe machine. From the experimental data, a regression model of the surface roughness was developed. The optimum machining conditions were obtained through the Taguchi method and a genetic algorithm and checked through confirmation experiments. In this study, it was concluded that the genetic algorithm used for determining the optimum machining conditions showed better results than the experimental outcome based on the orthogonal array and the optimum conditions obtained with the Taguchi method. Keywords: LM24 aluminium alloy, silicon carbide particles, coconut shell ash, surface roughness, Taguchi method, genetic algorithm V katerem koli postopku mehanske obdelave je klju~nega pomena dolo~itev optimalnih procesnih parametrov, ki omogo~ajo najvi{jo zahtevano kakovost obdelave pri najmanj{ih stro{kih. Avtorji so se v glavnem osredoto~ili na optimizacijo parametrov stru`enja, ki dolo~ajo povr{insko hrapavost hibridnega kompozita (LM24-SiCp-pepel kokosovih lupin) z Al matrico. Za to so uporabili Taguchijevo metodo in genetski algoritem. Vsi vzorci za pri~ujo~o {tudijo so bili izdelani s postopkom visoko tla~nega litja v testastem stanju (angl.: squeeze casting) pri optimalnih parametri~nih pogojih. Eksperimentalni preizkusi so temeljili na izbrani L9 (3) 4 ortogonalni matrici. Glavni vplivni parametri povr{inske hrapavosti, obravnavani v tej {tudiji, so bili: hitrost rezanja, hitrost podajanja, globina reza in polmer konice plo{~ice rezilnega orodja. Povr{insko hrapavost kompozitnih vzorcev so preverjali z merilnikom Mitutoyo SJ-210 po zelo hitrem stru`enju na ra~unalni{ko vodeni (CNC) stru`nici. Na osnovi eksperimentalnih podatkov so razvili regresijski model za povr{insko hrapavost. Optimalne pogoje mehanske obdelave so dosegli s pomo~jo Taguchijeve metode in genetskega algoritma in jih preverili s pomo~jo eksperimentalnih postopkov. Avtorji zakljuujejo, da optimalni pogoji mehanske obdelave, dolo~eni z genetskim algoritmom, dajejo bolj{e rezultate kot eksperimentalni rezultati, ki temeljijo na optimalnih pogojih, dolo~enih s Taguchijevo metodo za izbrano ortogonalno matrico. Klju~ne besede: Al zlitina LM24, silicij karbidni delci, pepel kokosovih lupin, povr{inska hrapavost, Taguchijeva metoda, genet...

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Aluminium based composites exhibit many attractive material properties such as increased stiffness, wear resistance, specific strength and vibration damping and decreased co-efficient of thermal expansion compared with the conventional aluminium alloys. Aluminium Matrix Composites consist of non-metallic reinforcement which offers advantageous properties over base material. Reinforcements like SiC, B4C and Al2O3 are normally preferred to improve the mechanical properties. Here Aluminum LM25 is selected as matrix material while Silicon carbide and Boron carbide are selected as reinforcement material. The fabrication of aluminium matrix was done by stir casting method. In the present study an attempt has been made to investigate the effect of three major stir casting parameters (stir speed, stir duration and preheated temperature of reinforcement material) on stir casting of Aluminium LM25 - SiC - B4C composite. Experiments were conducted based on Taguchi methodology. Taguchi quality design concepts of L9 orthogonal array has been used to determine S/N ratio and through S/N ratio a set of optimum stir casting parameters were obtained. The experimental results confirmed the validity of Taguchi method for enhancing tensile strength of castings.