Aluminum matrix composite materials being used in different sectors including automobile, aerospace, defense, and medical and are currently displacing unreinforced materials with their superior mechanical properties. The metal removal process of drilling is widely used in many structural applications. This study experimentally investigates the drilling characteristics of silicon carbide (SiC p )-reinforced Al 7075 composites produced by stir casting method. Also, two different drill materials with high-speed steel (HSS) and titanium nitride (TiN)-coated HSS carry out in drilling operation. The effect of operational parameters such as cutting speed and feed rate and materials parameters such as weight fraction of reinforcement and cutting tools on the surface roughness of drilled holes were evaluated in the drilling operations. The results of the drilling test indicate that the feed rate and cutting speed have a very strong effect on the surface roughness of matrix alloy and composite materials. The surface roughness ( R a ) values increased with increasing the feed rate and decreased with increasing the cutting speed. Under 0.10 mm/rev and 20 m/min drilling conditions and using HSS drill, surface roughness values for matrix, 5% SiC-, 10% SiC-, and 15% SiC-reinforced composites, were obtained 2.57, 2.59, 2.61, and 2.64 µm, respectively; besides, using TiN-coated HSS drill, surface roughness values were obtained 1.60, 1.63, 1.64, and 1.66 µm, respectively. An increase in the weight fraction of the abrasive SiC particle resulted in a very crucial deterioration quality of the drilled hole. TiN-coated HSS drills better performance exhibits than uncoated HSS drills for all the drilling operations about surface roughness properties. Short chip formations observed both the matrix alloy and the composite materials for two different drills in the drilling operations.
Reinforced PTFE materials can be designed to show high mechanical stability against harder materials under sliding wear conditions. Especially bearing metal-reinforced PTFE is of high practical interest. In this class of materials, bronze-filled PTFE was reported to obtain high wear resistance, a low coefficient of friction (COF), and excellent self-lubrication properties in sliding conditions. In the statistical approach of this work, PTFE composites reinforced with 25 vol%, 40 vol%, and 60 vol% bronze particles were evaluated against pure PTFE regarding wear behavior under varied wear test parameters, i.e., material, normal load, and sliding speed. Wear tests were planned to use a standard orthogonal array based on the Taguchi design method. An analysis of variance test was utilized to quantify the effects of test parameters on the wear behavior of the bronze/PTFE composites and pure PTFE. According to the variance analysis, the material type has the largest influence on the COF and the specific wear rate (SWR) under test conditions of this work. Both COF and SWR were found to be influenced by the material type (29.83% and 96.16%), the normal load (33.34% and 0.95%), and sliding speed (9.14% and 1.28%). The lowest SWR and COF values were achieved at the optimum wear test conditions where the wear test parameters were 1 m/s sliding speed (A4B2C2) at PTFE + 60 vol.% bronze reinforced composite 50 N application load and 0.32 m/s sliding speed (A4B3C1) at PTFE + 60 vol.% bronze reinforced composite 100 N application load, respectively.
30 March 2021 in Arabian Journal for Science and Engineering
In this study, the effect of modification Al-12Si (Etial 140) casting alloy with Al10Sr, CuSn5, and Al10Sr + CuSn5 master alloys has been investigated with respect to the cutting forces. In order to characterize the morphology of materials used in this study, metallography, hardness, density tests, and chemical analysis were performed. An optical microscope was used to examine the microstructure of the samples. Machinability tests were performed with the turning method by using a titanium diboride-coated cementite carbide cutting tool. All experiments were carried out under dry machining conditions with three different cutting speeds and feed rates with a constant cut depth. After the turning test, scanning electron microscope (SEM) images were used to examine the build-up edge (BUE) formation on the cutting tool. It was determined that the modification process has a positive effect on increasing the density and hardness. According to the results, it was observed that cutting ( Fc ), feed ( Ff ), and tangential ( Fr ) forces decreased for all material groups with increasing cutting speed V. Furthermore, Fc , Ff , and Fr forces increased for all material groups with increasing feed rate f . Finally, the highest cutting forces were observed on the Etial 140 c + Al10Sr master alloy.
Ceramic particle-reinforced aluminum matrix composites are gaining attention especially from the automotive and aerospace industry requiring light-weight and high-strength materials for various applications. Since the AlB2 reinforced composites are relatively new materials, there is no investigation into the machinability of such materials in the literature. Therefore, the aim of this paper is to study machinability of AlB2/Al-Mg3 composite materials to optimize cutting force and surface roughness during turning operation. Taguchi’s statistical approach has also been utilized for the optimization of the process parameters. The optimum conditions providing the lowest cutting force and surface roughness were estimated. For the experimental planning, L8 (27) orthogonal array and the smaller-the-better response criterion were selected to obtain optimum conditions. Analysis of variance was used to determine the most significant parameters affecting the cutting force and surface roughness generated. The optimum condition was predicted from the combination of following factors and their respective levels; the second level of material type (AlB2/Al-Mg3), first level of cutting tool (TiN coating), first level of feed rate (0.08 mm/rev) and first level of cutting speed (350 m/min). Confirmation tests were performed to determine the effectiveness of Taguchi’s optimization method using the optimal levels of test parameters. A good agreement with a confidence level of 99.5% has been observed between the predicted and tests results for both cutting force and surface roughness.
In this study, the friction and sliding behaviors of Polyetheretherketon (Peek) and Ultra-high-molecular-weight polyethylene (Uhmwpe) polymers when sliding against different counterfaces unreinforced Polyethylenimine (Ur-Pei), 20 vol.% glass fiber reinforced Pei polymer (20 vol.% Gf + Pei), wear durable Pei polymer (Dw-Pei), and stainless steel (Aisi 304L Ss) were determined and compared. Additionally, the tribological behaviors of these two polymers used in the industry were tested using the Taguchi optimization method. Mathematical equations were created using the regression method for optimal friction coefficient and specific wear rate. Accordingly, the optimal friction coefficient was obtained when Uhmwpe polymer was slid against Ur-Pei counterface with a 10 N application load. In contrast, the optimal specific wear rate was determined under 20 N load test conditions for Uhmwpe polymer against Ur-Pei counterface.