Process parameter optimization of A8011 pilfer-proof material using response surface methadology

Abstract

Commercial capmaking process include drawing, redrawing and several ironing operations. A8011 Pilfer-proof material is commonly used for making bottle caps, such as alcoholic beverages, water, nonalcoholic beverages and concentrated beverages. It is important to have prevention from taint or contamination, deformation hardening characteristics inhibiting the ease of opening, but actually ensuring clean snap seperation of the cap from the sleeve. Recently, it is also important for manufacturers to make deeper caps in order to provide flexible industrial needs.On the other hand, it is observed that during drawing process earing develops incured by the anisotrophic properties of the sheets.Minimizing the earing of products has always been the object of the can industry. Thus, a total understanding of earing behaviour during cold rolling is a prerequisite for a satisfied prediction.As it is important to improve the performance of the systems and increase the yield of the process without increasing the cost, optimization is an important phenomen. Conventional method for optimization is one-variable-at-a-time, which means there is one parameter change to find the optimimal operating condition while keeping other parameters at a constant level. But with this method it is impossible to measure the effect of the interactions, therefore most optimization studies are being carried out using response surface methadology(RSM).In this study, we worked on process pamaters of manufacturing A8011 pilfer proof material with 0,22mm thickness. The aim of the study was increasing the drawing depth and decreasing the earing behaviour. In ordere to optimize the responses we used a RSM design with four independent variables, homogenization thickness, homogenization temperature, annealing thicknesses and three levels for each. The experimental data were analyzed by response surface procedure using Minitab15 to fit the second order polynomial model predicted for optimization. Annealing temperatures and duration were kept constant at 350?C and 4 hours. The results obtained show that the mathematical model is useful not only for predicting optimum process parameters but alsı process optimization. The resulting drawing depth was computed as 6.481mm and plastic strain ratio as 0,0. Using the optimal combination of these parameters is useful in minimizing the cost arised as a result of earing and cracks occurred as a result of drawing process.