Parametric Study of Fixtured Vibropeening

Abstract

Vibropeening is a surface treatment process, which combines the peening effect of introducing residual stress with the polishing effect of reducing surface roughness in one single process step. Vibropeening equipment induces vibrations into the media to impart residual compressive stresses in sub-surface layers, as well as polishing on the surface of the work piece. In addition to process parameters, such as vibration frequency, amplitude, and media mass, which are well known in literature, this paper will focus on the study of two additional parameters: immersion depth and process time. It was found that the lower-middle section of the vibratory trough produced the highest Almen deflection. Different continuous treatment times were also studied to explore the maximum introducible residual compressive stress state, and it was concluded that an optimal time range is required to achieve the best residual stress profile. The study demonstrates that different process parameters can influence the effectiveness of the vibropeening process, and that these can be potentially optimized for higher treatment capability.

Investigation on the Relationship Between the Vibratory Peening Process Parameters and Almen Intensity

“…10b) for all part insertion depths investigated here. This agrees well with previous works showing improvement in Almen intensity with these two processing parameters [6][7][8].…”

“…Besides, some studies used light abrasive media like those used in vibratory finishing [1,5,6]. Some others used steel media [7][8][9][10][11].…”

“…Unfortunately, the evaluation of each parameter effect is incomplete since the specimen immersion depth was not reported and not all levels of frequencies were tested for both media masses. Chan et al [8] studied the combined effects of eccentricity between 40 and 75%, frequency between 20 and 25 Hz, and specimen immersion depth from 0 to 20 cm with a tub vibrating in a circular pattern. The highest Almen intensity they found was 0.11 mmN for 75% eccentricity, 20 Hz frequency, and 13 cm immersion depth.…”

Advanced Surface Enhancement

“…Composite surface modification [2] was used to achieve simultaneously the benefits of surface peening and smooth finish. Vibropeening [3] is another technique that combines the advantages of introducing residual stress through peening with the reduction of surface roughness by polishing in a single processing step.…”

Effect of Surface Finishing State on Fatigue Strength of Cast Aluminium and Steel Alloys

“…Vibratory finishing as a post manufacturing process leads to high reproducibility as well as a good surface quality with low scatter of surface roughness values as function of the process settings [ 50 , 51 , 52 ]. But the fatigue design may be affected by this highly reproductive finishing processes due to the evocation of compressive residual stresses in the surface layer [ 47 , 53 , 54 ] and a change of surface layer hardness due to small plastic deformations [ 54 , 55 ], depending on the material as well as the polishing medium. These effects of vibratory processing lead often to an increase of the long life fatigue strength [ 56 ], but may also reduce fatigue strength [ 57 ] depending on the effective residual stress state in the surface layer.…”