A crimping system, a control circuit for a crimping machine, and a method to be applied in them, in which: a work piece (15) is subjected to a first force effect by an actuator (5) that is controlled by the pressure of pressurized medium, wherein said force effect is proportional to said pressure and causes a desired deformation in the work piece (15); a follow-up measurement is taken, whose measurement result is proportional either to the dimension of the work piece (15) or said pressure; the work piece (15) is subjected to a second force effect but by applying a reduced pressure which is lower than the pressure that contributes to said deformation; and a verifying measurement is taken, whose measurement result is proportional to the dimension of the work piece (15), when said reduced pressure controls said actuator (5) and the work piece (15) is still in the crimping machine (1).