The main aim of this paper is to present an environmentally friendly method for aluminum recycling. Development of new recycling technologies in order to increase scrap reuse potential and CO 2 emission savings are of the main importance for aluminum circular economy. In this paper, aluminum chips waste was recycled without any remelting phase in order to increase energy and material savings. The presented process is usually called solid state recycling or direct recycling. Solid state recycling process consists of chips cleaning, cold pre-compaction and hot direct extrusion followed by a combination of equal channel angular pressing (ECAP) and heat treatment. Influence of holding time during solid solution treatment and both artificial aging time and temperature on mechanical properties of the recycled EN AW 6082 aluminum chips were investigated. A comprehensive number of the experiments were performed utilizing design of experiments approach and response surface methodology. Regression models were developed for describe the influence of heat treatment parameters for presented solid state recycling process on mechanical properties of the recycled samples. Utilizing novel procedure high quality recycled samples were obtained with mechanical properties comparable with commercially produced EN AW 6082 aluminum alloy in T6 temper condition. Metallographic analysis of the recycled samples was also performed.In order to reduce the negative effect on the environment, various authors recognized solid state recycling (SSR) as a possible alternative to the conventional aluminum recycling process [4][5][6][7][8][9]. When SSR is employed, material losses are much smaller because the remelting phase is completely avoided. Aluminum is a highly reactive material and it has a tendency to form aluminum oxide on its surface. This is even more pronounced for lightweight aluminum scrap due to its high surface to mass ratio. During the remelting process this oxide is floating on the melt surface mixed with dross. Therefore, aluminum lightweight scrap (chips, foils, and sheet skeletons) is problematic when conventional recycling technology is used because up to 20% of the aluminum can be lost due to the mixing with dross and burning [9]. According to previous research papers concerned with SSR process, it is possible for material yield to be over 90% when this type of recycling is employed, while energy consumption can be only 10% compared to conventional recycling process that uses remelting [6][7][8]. Furthermore, manufacturing profiles from solid state bonded chips gives a 96% saving in CO 2 emission compared to production from billets made by conventional recycling of aluminum manufacturing waste [8]. In order to produce SSR samples with appropriate quality, the combination of the high temperature, normal stress, shear stress, and plastic deformation should be achieved [6,7]. Therefore, the most used process for SSR is direct hot extrusion, but lately severe plastic deformation (SPD) processes opened new possibilities [10]. SPD i...

The latest trends in machining research show that great efforts are being made to understand the impact of different cooling and lubrication techniques as well as cutting parameters on machining performances. This paper presents the investigation results of different cutting parameters and different cutting environments such as dry machining, minimum quantity lubrication (MQL) and minimum quantity lubrication with compressed cold air (MQL+CCA) on average surface roughness, cutting force and material removal rate. The experiments were designed based on three input parameters and three different cutting environments when turning of EN AW-2011 alloy. Taguchi-based grey relational analysis was used to identify the optimal process parameters by which minimum values of surface roughness, minimum value of cutting force and maximum value of material removal rate will be achieved. The results showed that minimum quantity lubrication in the stream of compressed cold air, in comparison to dry and minimum quantity lubrication machining, gives the best machining performances. Therefore, the use of MQL + CCA method, which reduces the amount of lubricant may represent in the described extent of turning operations an alternative to turning processes most often carried out by wet method that causes considerable costs for purchasing, maintaining and using cutting fluids.

No abstract

The required quality of the product arises from the customer preferences and functional requirements of the product and is determined mostly by the machining operation. Properly selected machining parameters in machining processes are of great importance for improving process efficiency and product quality. The aim of this paper is to find cutting parameters with which above mentioned process and product characteristics will be achieved. Experiments were performed according to Box-Behnken design of experiments. Influential input variables were cutting speed, feed per revolution and depth of cut and output variables were surface roughness, power consumption and material removal rate. Multi-objective optimization function was developed to find the machining parameters with which the lowest power consumption, the best surface quality and the greatest material removal rate will be achieved.

No abstract

No abstract

The main aim of this paper is to present and evaluate thermomechanical treatment for semi‐solid feedstock production of A380 (AlSi9Cu3(Fe)) aluminum alloy. Equal channel angular pressing (ECAP) is used to heavily deform and refine as cast dendritic microstructure with needle like eutectic appearance. The deformed microstructure is easily changed to globular microstructure by recovery and recrystallization mechanisms during heating at the semi‐solid temperature range which is a crucial factor for quality semi‐solid feedstock preparation. The microstructural evolutions investigations during semi‐solid heating at different holding times is carried out utilizing optical microscope and scanning electron microscope accompanied by energy dispersive x‐ray spectroscopy. Homogeneous distribution of the silicon particles and intermetallic compounds around globular primary aluminum phase is observed. The used approach is appropriate and seems highly promising for preparation of the quality semi‐solid feedstock.

No abstract