A mechanism is reactionless or dynamically balanced when there is no shaking force and shaking moment applied to the base during mechanism movement. The theory for designing reactionless 2 degree-of-freedom (DOF) planar parallel manipulator is discussed in this paper. The legs of the manipulator are four-bar 2-DOF mechanisms with revolute joints. The dynamic balancing conditions of the manipulator are derived, considering that the time rate of the total linear and angular momentum have to be vanished. The dynamic balancing equations first are obtained and illustrated through a numerical example and finally verified by computer simulation using ADAMS software. Manuscript profile

Burnishing is a chip-less finishing process, in which a hard roller or ball presses the surface layer of part to perform plastic deformation in the surface layer and produce improved finish, enhanced hardness and compressive residual stresses on the surface of special materials such as Aluminum and Brass. In the following research, the effect of input parameters such as feed rate, cutting speed, number of passes , burnishing force and cooling system which is applying by minimum quantity of lubrication (MQL) on surface roughness and micro-hardness in roller burnishing of Aluminum alloy 6061 has been investigated. Taguchi method is used for design of experiments and special burnishing tool is used for this research. The optimization results show that the effect of feed rate and burnishing speed is significant on surface roughness and burnishing force and the number of passes plays important role in micro-hardness. The minimum surface roughness in burnishing of aluminum alloy 6061 was 0.138 μm and the maximum was 0.475 μm. The maximum micro-hardness in roller burnishing Aluminum alloy 6061was found 122 HB and the minimum was 100 HB. Manuscript profile