AERONAUTICAL AND MECHANICAL ENGINEERING Abrasive Flow Machining : Major Research Areas & Analysis
Abrasive flow machining also known as abrasive flow deburring or extrude honing, is an interior surfac e finishing process characterized by flowing an abras ive-laden fluid through a work piece. This fluid is typically very viscous, having the consistency of p utty, or dough. In this paper, the main purpose of the process is to investigate the surface finishing of die steel with the use of abrasive flow machining. Grinding medium is pressed along the contours at a defined p r ssure and temperature. Depending on the respectiv e machining task, different specifications of media a re used. The surface finishing is better with use o f abrasive flow machining process as compared to other flow ma chining processes.
Experimental investigation and mechanism of material removal in nano finishing of MMCs using abrasive flow finishing (AFF) process
Abstract Aluminum alloy and its composites appear to have a good future as a candidate material for engineering and structural components. Finishing of these materials is a big challenge as they are heterogeneous in nature having abrasive particles randomly distributed and oriented in the matrix material. Metal matrix composite (MMC-aluminum alloy and its reinforcement with SiC) workpieces were initially ground to a surface roughness value in the range of 0.6 ± 0.1 μm, and later were finished to the R a value of 0.25 ± 0.05 μm by using Abrasive Flow Finishing (AFF) process. The effects of different process parameters, such as extrusion pressure, number of cycles and viscosity of the medium were studied on a change in average surface roughness (Δ R a ) and material removal. The relationship between extrusion pressure and Δ R a shows an optimum at about 6 MPa. In the same way, the relationship between weight percentage of processing oil (plasticizer) and Δ R a also shows an optimum at 10 wt%. Further, an increase in workpiece hardness requires more number of cycles to achieve the same level of improvement in Δ R a . Material removal also increases with an increase in extrusion pressure and number of cycles while it decreases with an increase in processing oil content in the medium. It is also concluded that the mechanism of finishing and material removal in case of alloys is different from that in case of MMC.
In search of optimum chest radiography techniques.
A nation-wide study of chest radiography in Sweden had previously revealed a large variation in the physical and technical factors involved, in particular the radiation dose. In this study the image quality could not be assessed unambiguously. The aim of the present study was to try to establish a correlation between visual grading of radiographs and physical and technical factors in order to find the optimum chest X-ray system. The physical and technical performance of 24 chest units was evaluated. Radiographs were taken of an anthropomorphic chest phantom supplied with test structures simulating various pathologies. Image quality was assessed by visual grading analysis of the radiographs. The physical and technical parameters of the units rated best were used to exemplify good radiographic practice. The results were in agreement with the recommendations issued by the Commission of the European Communities (CEC). It was also shown that low radiation dose is compatible with high-quality radiographic imaging of the chest.