Optimization of microstructural and mechanical properties of brass wire produced by friction stir extrusion using Taguchi method

Friction stir back extrusion is used to produce brass wires from its chips, and then the process parameters are optimized using Taguchi L9 orthogonal design of experiments. The rotational speed, traverse speed, and the produced wire diameter are the parameters taken into consideration. The optimum process parameters are determined with respect to grain size, microhardness, and ultimate pressure strength of the produced samples. The predicted optimum values for output parameters are confirmed by conducting the confirmation test using optimum parameters. Analysis of variance shows that the rotational speed is the most dominant factor in determining the grain size and microhardness of the produced wires, and the tool traverse speed and the wire diameter are the second and the third effective parameters. However, in terms of the produced wires ultimate pressure strength, the traverse speed is the most dominant factor rather than the rotational speed. The optimum values for the rotational speed, the traverse speed, and the wire diameter are 500 r/min, 31.5 mm/min, and 6 mm, respectively, and the produced wire, by these optimum parameters, presents 14.17 µm, 127.1 HV, and 904.7 MPa for the grain size, the microhardness, and the ultimate pressure strength, respectively.

Influence of the vent pipe diameter on the discharge capacity of a circuit vent building drainage system

Experiments on different vent pipe diameters (nominal diameters of 100, 75 and 50 mm; DN100, DN75 and DN50, respectively) in a full-scale circuit vent building drainage system were conducted in a 60 -m high structure, and the wastewater discharge capacities as a function of vent pipe diameter were measured. Critical pipe pressures, water seal losses of sanitary fixtures and air flow rates were measured. The ultimate pressure values in pipes on lower floors were larger than those in pipes on higher floors using DN100 and DN75, which was opposite to the results with DN50. A positive correlation between the ultimate pressure values and floor heights, as well as between ultimate pressure values and water seal losses, was found for DN100 and DN75. The maximum discharge flow of the three systems using DN100, DN75 and DN50 vent pipes was 17.0 L/s, 14.0 L/s and 7.5 L/s, respectively. Nevertheless, in China, the maximum wastewater discharge capacity in a circuit vent system adopting a DN100 vent pipe connected to a DN100 drainage stack in tall residential buildings is 11.5 L/s according to the Code for Design of Building Water Supply and Drainage. Thus, the vent pipe diameter DN75 can fully meet the design requirements of drainage systems for high rise buildings in China. The engineering cost associated with material expenses for building drainage systems can be minimised by optimising the size of vent pipe based on required capacity rather than using a single size universally. Practical application: The engineering cost associated with material expenses for building drainage systems can be minimised by optimising the size of vent pipe based on required capacity rather than using a single size universally.