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Cross-sectional profile and surface quality of micro-fins of a heat sink play a significant role in the transmission of heat from microelectronic and MEMS devices subjected to intense heating. Several processes are available for the fabrication of such pin-fins, Reverse micro electro discharge machining (RµEDM) among them is one of the most promising. A wide range of parameters associated with this process provides varying competence for surface roughness. An effectively modeled and simulated surface, thus, may serve as a database for an operator to study the effect of parameters for the desired surface. A single discharge model is developed to study the volume removal by each discharge pulse to achieve the goal. ANSYS finite element code is used to simulate the process to find the volume of the crater for further prediction of average surface roughness values. The model's predictions are compared with experimental results for verifying the approach and presented a good agreement with them. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM) is recently used to manufacture biomedical implants as the customized fabrication of the desired complex shapes is easily achievable with reduced manufacturing time and material waste. However, the poor surface quality of additively manufactured products is a major concern over biomaterials' functionality. Magnetorheological Fluid Assisted Finishing (MFAF) process is an advanced surface finishing process used to improve the workpiece surface quality without altering surface topography. Selective Laser Melting (SLM) is utilized in the presented study to fabricate biomaterials using SS316L powder, and surface quality is further enhanced through the MFAF process. However, average surface roughness (R a) only delivers the details regarding the average altitude of peaks and depth of valleys from the central line. Therefore, kurtosis (R k u) and skewness (R sk) analysis of the polished surface are also carried out to determine detailed surface characteristics. The bio-tribology analysis of the polished surface of the AM implant determines its sustainability inside the human body. Hence, a wear test utilizing the pin-on-disc process is performed on the finished surface to determine the efficiency of the polishing process during tribological contact of the biomaterials with the bone. Further, the improved surface roughness parameters (R a , R k u , and R sk) after the MFAF of AM implant's surface are also investigated with an optical profilometer and scanning electron microscope. The MFAF process produced a highly polished surface on the biomaterial and a final R a value of 32.46 nm is attained after polishing from its initial value of 8.32 μm with a decrease in wear rate (i.e., from 9.86 × 10−5 mm3/min to 0.46 × 10−5 mm3/min). The value of kurtosis less than three (i.e., 0.79) indicates that the flat peaks are generated on the surface irregularities after MFAF. Similarly, the negative skewness (i.e., Rsk = −0.28) represents that the number of peaks is less than the valleys. It indicates that the chances of wear out of the surface irregularities from the workpiece on their tribological contact are very low. • Surface characteristics improvement of Selective Laser Melted biomaterial (SS316L). • A mirror-like polished surface is achieved through Magnetorheological Fluid Assisted Finishing process on the biomaterial. • A final R a value of 32.46 nm is attained after polishing from its initial value of 8.32 μm. • The wear rate is reduced on the polished surface from 9.86 × 10−5 mm3/min to 0.47 × 10−5 mm3/min. [ABSTRACT FROM AUTHOR]

This study analyzes the effects of machining parameters on the surface roughness and macro surface characteristics when machining Al-6082 T6 alloy of ∅30 and 240 mm in size using abrasive water jet (AWJ) turning processes. The material removal tests were conducted using a computer numerical control (CNC) abrasive jet cutting machine for different parameters of nozzle feed rate (10, 15, 20 and 25 mm·min −1 ), abrasive flow rate (50, 150, 250 and 350 g·min −1 ), spindle speed (25, 50, 75 and 100 min −1 ) and standoff distance (2, 5, 8 and 11 mm). Pump pressure at 350 MPa, abrasive type of Garnet and size of 120 Mesh, and nozzle diameter of 0.75 mm are kept constant throughout the experiments. When macro surface characteristics were analyzed, it was found that increased spindle speed, decreased nozzle feed rate, increased abrasive flow rate and lower standoff distance resulted in smoother surfaces. According to the findings of this study, best results were obtained when spindle speed and abrasive flow rate were increased. [ABSTRACT FROM AUTHOR]

Abstract: Abrasive flow finishing (AFF) is used to deburr, polish or radius surfaces and edges by flowing a semisolid abrasive medium over the intended surface to be finished. Such finishing operations play a crucial role in manufacturing process of machine parts. The cost escalates sharply when the requirement is to achieve surface roughness values near nano levels. The need for finishing is to avoid power losses due to friction, increase the wear resistance and to provide a long serviceable life to the equipment. AFF is used in the industries especially in the case of finishing complex internal and external shapes. However, AFF is a time consuming process and any effort to reduce the process time even marginally saves production time and cost of the finished product. In the present study, an effort is made towards improving the performance of AFF process by providing rotary motion to the workpiece (R-AFF: rotational abrasive flow finishing). Preliminary experimental comparative study is done on AFF and R-AFF processes to compare their process performance in terms change in R a (ΔR a) and material removal. Later complete experimental study on R-AFF is conducted using central composite rotatable design and the responses are plotted using response surface methodology. The workpiece materials used in the present study are Al alloy, Al alloy/SiC (10%) and Al alloy/SiC (15%) metal matrix composites (MMCs). The results of R-AFF are encouraging. The present study shows that rotational speed of workpiece has significant effect on output responses (ΔR a). Indigenously developed semi solid abrasive laden medium is used in the present study. Overall, the experiments have shown that R-AFF has a very promising future for the industries in terms of better finishing. [Copyright &y& Elsevier]