A newly developed ball burnishing tool was designed and tested for surface finishing of large flat surfaces in a shortest possible time. Optimization and analysis of the burnishing process were carried on AISI 1010 steel hot-rolled plates using the Taguchi technique and response surface methodology (RSM) to identify the effect of burnishing parameters (i.e., burnishing speed, burnishing force, and feed rate) on surface roughness, surface hardness, and microstructure of burnished surfaces. The optimal burnishing parameters were found after conducting the TaguchiÕs L 25 matrix experiments and obtaining the response models for the surface roughness and the hardness. It was found that the burnishing force has the most influential effect on the surface roughness and hardness, followed by the burnishing speed, and least influence by the feed rate. In addition, microstructural examinations of the burnished surface indicate that burnishing force more than 400 N causes flaking of the burnished surfaces. The optimal burnishing parameters for the steel plates were a combination of a burnishing speed of 235 rpm, a burnishing force of 400 N, and a feed rate of 0.18 mm/rev. Using these parameters, the mean surface roughness has been improved from Ra = 2.48 to 1.75 lm, while the hardness increases from 59 to 65.5 HRB.

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Conventional ball burnishing processes using a roller or a ball pressed against round or small flat surfaces have long been used to improve hardness, fatigue strength, and wear resistance of mechanical parts by plastic deformation. However, the treatment of large flat surfaces using conventional techniques is rarely considered because of its time consumption. In the present work, the optimal burnishing parameters of rolled sheets of aluminum 1050A are determined by means of a newly developed burnishing tool device especially designed to treat large flat surfaces with orders of magnitude reduction in burnishing time. Experiments were designed and performed on a machining center based on response surface methodology with central composite design. The burnished specimens were then tested to find the burnishing condition under which ductility was improved. This study has resulted in significant new insights into the effect of burnishing on the surface quality and workpiece properties of aluminum 1050A plates. A second-order mathematical model, validated using data obtained from atomic force microscopy, was developed to predict the surface roughness as functions of speed, force, and feed rate. The results indicate that burnishing of aluminum 1050A plates improves its ductility, but not its micro-hardness. Following the various burnishing conditions, the micro-hardness measurements range from 40 to 43 HV (50 g), indicating that there is little or no hardening. Although a moderate effect with varied degrees is found on the surface roughness as functions of the investigated parameters, the burnishing force has a significant effect on ductility. The results also indicate that lower values of roughness do not guarantee better ductility for aluminum 1050A plates. Furthermore, the effect of the burnishing loads on the residual stresses was found to depend on the feed direction.

Natural fibers as an alternative fiber reinforcement material have significant advantages over glass. Indeed, they are more environmentally friendly, healthier and safer. Their application in polymer composites requires the understanding of their structure and mechanical properties. Other advantages of using the cellulose fibers as reinforcement are their low densities and their non-abrasive aspect. Various natural fibers have been widely used. Others, however, remain of limited use such as in the case of palms. This study aimed at introducing palm fibers to be used as reinforcement in a polymeric matrix enabling production of economical and lightweight composites for load-carrying structures. First, an investigation of the extraction procedures of fibers from folioles and leafstalks of doum palm was undertaken. Secondly, the mechanical behavior of the treated and untreated doum palm fibers was studied to determine their mechanical properties. Finally, we compared the mechanical properties of the different parts of the tree with other natural fibers.

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