Qiqihaer Northern Machine Co The artful application of vibratory stress relief   Abstract: Stress exists within any work pieces and during any processing. Under some special occasions, the pre-stress is beneficial, but under most cases, stress within work pieces is harmful. If not serious, the inner stress will cause deformation of work pieces; if serious, it will cause accident due to a reduced life span of work pieces. While the application of Vibratory stress relief tech has well solved the stress problem within work pieces, and helped to avoid deformation forever. Key words: vibratory stress relief   inner stress    deformation   1. Preface We opened a semi-circle slot on the axle of cylindrical parts, of which 100% were detected to have deformation with none meeting the drawing requirement. It was caused by the rebalance of inner stresses after processing. As the axle cylindrical parts could not be corrected, this became a huge problem for our company. There are two methods as follows to process the work piece: First, open the slot, followed by processing the outer circle and fixing the size of inner hole. This method can tackle the deformation problem, but as the slot is opened down to the central line, it¡¯s difficult to make the inner hole to be exactly done according to the drawings. Second comes the way to process and fix the inner hole and outer circle first and then to open the slot. Thus the size can meet the requirement of the drawings, but deformation problem remains. Considering our real situation, we adopted the second method.   2. Draw up our processing plan First of all, we should relieve the inner stress within work pieces. Without the inner stress, work pieces won¡¯t distort, so inner stress should be relieved after processing. The thermal stress relief method will cause oxidation on the work piece surface and deformation, which are bad for the work pieces that already are processed and fixed. Therefore, we adopted Vibratory stress relief for the following reasons: first, vibration will not cause oxidation of the surface, and it completely relieves the stress. Second, the work pieces treated through finish machinery will not deform in Vibratory stress relief process. In this way, we decided to use this method. We took some necessary measurement on the work pieces such as: first half open the semi-circle slot on the work piece and leave a rib at the center of the circle, which is equivalent to crude machinery, and then go through Vibratory stress relief process.   3. Vibratory stress relief We introduced the Navigator Vibratory stress relief equipment from Beijing Semboo Science and Technology Co,. LTD. The equipment , when treat the work pieces, can auto-select vibration parameter and optimizing the selection of more than 5 vibration frequencies to relieve the residual stress from multi-dimension. Besides, it also boasts low noise, proved to be a green and environmental friendly product to completely relieve the residual stress. We fix the work pieces on the platform for vibration treatment. Several pieces for each time. 4. Conclusions After vibration stress relief, we remove the rib on the work piece during processing. After inspection, the precision remains unchanged pre and after vibration, which is to say, no deformation occurs. Then we launched the same experiment on three other work pieces with the same result. At last we improve the technics, and the work pieces processed through this technics are 100% qualified. Our biggest difficulty has been solved since then, and this is the successful application of Semboo¡¯s Vibratory stress relief tech in our production.