now thats an interesting concept, but I wonder how practicable it is compared to having a shop do your parts with a standard machine and how effective it is on oddly shaped parts
http://www.webs1.uidaho.edu/mindworks/M ... Poster.pdf
http://www.metalimprovement.com/shot_peening.php
Shot peening is a cold working process in which small spherical media called shot bombard the surface of a part. During the shot peening process, each piece of shot that strikes the material acts as a tiny peening hammer, imparting to the surface a small indentation or dimple. To create the dimple, the surface of the material must yield in tension. Below the surface, the material tries to restore its original shape, thereby producing below the dimple, a hemisphere of cold-worked material highly stressed in compression.
Nearly all fatigue and stress corrosion failures originate at the surface of a part, but cracks will not initiate or propagate in a compressively stressed zone. Because the overlapping dimples from shot peening create a uniform layer of compressive stress at metal surfaces, shot peening provides considerable increases in part life. Compressive stresses are beneficial in increasing resistance to fatigue failures, corrosion fatigue, stress corrosion cracking, hydrogen assisted cracking, fretting, galling and erosion caused by cavitation. The maximum compressive residual stress produced just below the surface of a part by shot peening is at least as great as one-half the yield strength of the material being shot peened.
Shot peening is a specialized blasting process that bombards a metallic work piece with a round abrasive, typically steel shot, glass beads, or ceramic shot, thereby compressing the surface. This compression can greatly improve the strength and fatigue life of the part. An analogy would be the blacksmith that hammers a sword to increase its strength.
Parts that are commonly shot peened include:
Valve Springs
Suspension Springs
Leaf Springs
Torsion Bars
Gears
Connecting Rods
There are many others. Shot peening has the potential to improve the service life of nearly any metallic work piece that is subject to repeated stresses.
To work properly, however, shot peening requires more exacting controls over media velocity, abrasive flow rates, work piece exposure to the blast, and abrasive size and shape, than normal blast cleaning operations. Because of the need for these strict controls, shot peening equipment is almost always automated so that the process is consistent and repeatable.