In this paper, we discuss the manipulation of planar objects by multiple cooperating mobile robots using the concept of Object Closure. It is the condition under which the object is trapped so that there is no feasible path for the object from the given position to any position that is beyond a specified threshold distance. We proposed the concept of Dynamic Object Closure for achieving object caging task that robots team is able to cage a moving object after a predefined time interval. A Random Caging Formation Testing algorithm (RCFT) is proposed for checking Dynamic Object Closure condition. Some simulation results are presented for illustrating the validity of the proposed algorithm.