This paper mainly aims to disclose the effects of cutting conditions on the turning of aluminum alloy 7075 (AA7075). First, the artificial neural network (ANN) was programmed to investigate how cutting parameters, namely cutting speed, feed rate and depth of cut, affect the surface roughness of AA7075. Then, the taguchi method was introduced to design an L 27 orthogonal array, in which each cutting parameter is considered on three levels. The results of orthogonal analysis were used to train the ANN called backpropagation neural network (BPNN) on MATLAB. The trained network was applied to predict the surface roughness of AA7075 through MATLAB simulation. Meanwhile, an experiment was conducted under the same conditions. The experimental results were found consistent with the simulation data, indicating that the BPNN is suitable for simulation the turning of AA7075. It is also learned that the cutting speed has the greatest impact on surface roughness; the surface roughness is negeatively correlated with feed rate; the negative correlation is positively mediated by the cutting speed.

Polishing is a surface machining technique to produce a high-quality finished surface on the product. It is a multistage process, in which each subsequent stage uses a finer abrasive. This paper aims to design and fabricate a polishing machine that performs polishing stages continuously, eliminating the idle time in the polishing process. The designed machine consists of four spindle heads, each of which carries a unique flap wheel. The flap wheels can raise or lower according to the size of the workpiece to be polished. Three types of rollers were adopted in the machine: a mild steel roller coated with heat resistant rubber, a hylam roller and a nylon roller. A pneumatic clamping system was placed at the feeder to fix and hold the workpiece. In addition, the compressor pressure is regulated by a pressure regulator. A prototype of the polishing machine was fabricated according to the design, and used to polish several types of workpieces. The results show that this machine can polish stainless-steel flat bars, square tubes and rectangular tubes into 10mm-150mm width products, operate at a high speed of 2,000~3,000 rpm, and, most importantly, execute multiple polishing operations continuously. The proposed polishing machine is helpful to the automation of the polishing industry.