abdulbadii
Member
How is it harmful to a DC motor specified max 15V or 18V, 2A, given input by a SMPS output 24V max 2A?

MAX could be a damaged label listing.You will also overload the SMPS as the motor will take more than the 2A the SMPS can supply.
Mike.
BTW, how can MAX be two different values? Unless, of course, it's two different motors.