The use of an air jet to clean the products during the manufacturing is usual in an industrial environment. In this paper the problem of the removal, from the inner of the tube, of the waste arising from the cutting operation by means of an air blowing system is analysed. In order to obtain indications about the real importance of the involved parameters and their effects, a numerical procedure, based on CFD analysis trough the code STAR CCM+, has been settled. The effects of the different parameters were highlighted. The results are congruent with the experience, indicating that the adopted solution is not suitable for the small tubes. Therefore, a different blowing solution is investigated, with the object to improve the cleaning capabilities of the system. The results for the new blowing solution provide a significant improvement of the capability to remove the waste arising from the cutting operation can be expected.