Active part-mating algorithms using 6-axis force sensor data for the assembly automation and/or telerobotics are presented and experimented. Parts to be mated are cylindrical and have no chamfers. Most of assembly tasks can be divided into two basic modes; the normal mode which has only a positional error and the tilted mode which has an orientational error as well as a positional error. In the normal mode, a simple and fast algorithm using the are tangent(atan2) function value of the x and the y components of the moment around the tip of the peg is presented and experimented. In this algorithm, by aligning the world frame of the robot with the sensor frame in a specific manner, the value of the atan2 function tells us the direction of the positional error and the direction the robot should move to. In the tilted mode, the presented algorithm distinguishes a contact external to the hole from that of internal to the hole by comparing the tangential component of the contact force with the vertical component of it. Then, it moves an external contact into an internal contact by assuming that only a positional error exists (i.e. same as normal mode). After moving the peg into the hole, it corrects an orientational error. Finally, in the combined mode of the above two, there is no a priori information about the relative tilt between a peg and a hole. In this case, the algorithm to perform part-mating in spite of the tilt is only the combination of the above two algorithms because of the fact that the algorithm for the tilted mode distinguishes an external contact from an internal contact.