Proc. of the 5 th International Conference on Advances in Mechanical Engineering (ICAME-2011), June 06-08, 2011 S.V. National Institute of Technology, Surat – 395 007, Gujarat, India 11 Experimental and Numerical Optimization based Approach for Fibre Reinforcement in Rotomolding Nikhil Gakkhar, A.K. Digalwar * , Ashish M. Gujarathi * Birla Institute of Technology and Science (BITS) Pilani 333031, Rajasthan, India *Corresponding Authors (e-mails akd@bits-pilani.ac.in, ashishg@bits-pilani.ac.in) This study deals with the experimental analysis of fiber reinforcement of rotational molding processes and its numerical model based evaluation. The experiments are carried out to get patterns, using linear low density poly- ethylene (LLDPE) and glass fiber, to improve its surface finish, strength and hardness. For that design of experiment (DoE) is performed and then various experiments has been conducted. The theoretical optimum value is obtained and is compared with the experimental values. The optimum value by experimental calculations i.e., the weight of LLDPE and weight of fiber, with constant time, is in the permissible error with the theoretical value. This justifies that the experimental designs obtained are of optimum/local optimum value. Furthermore using a random population of points is generated and factors, which can improve the optimum design, are identified and reported. 1. Introduction Variety of Polymers due to their improved properties have gained popularity in the recent past and thus are being used by several manufacturing industries as a basic row and intermediate raw material. The polymer processing industries use various techniques for plastic formations. Among the various methods of plastic casting, rotomolding process has wide application in this field. Rotomolding was not developed commercially earlier but in mid 60’s the development had started in this field. With the formation of the Association of Rotational Moulders (ARM) in 1976, the popularity of rotomolding process has increased. And by late 80’s various polymers and resins are used for the same. Liu et al. [1] discussed the history of the development of this process, using LLDPE polymer. Application of Various polymers, which are used, was discussed by many researches [2]. Later on, in 2000 resin and glass fibre were added to rotomolding process for better yield. Waigaonkar [3] suggested various ways for resin selection for this process. However, despite tremendous exploration in resin and polymers of rotomolding, very few research attempts have been done on fibre reinforcement with rotomolding parts. T. Aurich and G. Mennig [4] discussed few engineering properties of flax fibre and its application in Rotomolding. But, the area of glass fibre reinforcement in rotomolding process is still unexplored. With all these finding there exist a gap to find out the better approach for fiber reinforcement for rotationally molded products. This study is performed to overcome that gap in the research area of rotomolding. 2. Experimental For this experiment the design of experiment method is done by full factorial method. The main purpose of this design is to get the optimum point for the experiment and then compare it with the experimental data. The values of different weights of LLDPE and Fibre along with the weight of resins are taken as parametric variables and equations are derived to optimize the variable for better surface finish. Using statistical software Minitab (v15.0) the factorial run is performed and optimum points are taken for 30 runs. With these points the surface plot is constructed and shown in Figure 1. Figure 1 shows the maxima (the optimum point) for the given range of LLDPE and fiber value. The Range of fiber is from 90 grams to 150 grams and for LLDPE it’s 50 grams to 600 grams.