A method is provided for ensuring and/or checking the quality of a crimping using a crimping machine for crimping a cable with a contact sleeve and using a first optical sensor for detecting and/or recording first image data of the contact sleeve and using an evaluation electronics system. The method includes detecting the first image data of the contact sleeve by the first optical sensor; carrying out, via the evaluation electronics system, a first comparison of the first image data of the first optical sensor with first reference data of a predetermined contact sleeve; checking the first comparison for the presence of a predetermined first criterion; and, if the predetermined first criterion is satisfied, outputting a first signal. The detection of the first image data and the first comparison and the checking for the first criterion and the output of the first signal are carried out before the cable is crimped with the contact sleeve. A crimping machine suitable for carrying out the above method is also provided.