Robot's economic repeatability

The economic feasibility of a new venture plays a decisive role in its acceptability in the marketplace. The application of robots in assembly processes is no exception. Being relatively new in assembly of industrial components, thorough investigation and experimentation usually precedes robot integration in production systems. In today's marketplace several classes of robots are available with diversed specification range and operational cost. One of the most important robot specifications in assembly is its repeatability. In the same class of robots, those with smaller repeatability range are usually more expensive to operate. In this paper a mathematical model is introduced to aid the practicing engineers in choosing the most economical robot for the considered assembly processes. The model relates the interaction between the random nature of the dimensions of the parts presented for assembly, the clearance between the mating surfaces and the robots repeatability and its operational cost, and determines their effect on the probability of successful assembly. The results of the model are tabulated showing the acceptable clearance range of the assembled parts and the optimum robot's repeatability range for the process under consideration.