Blast cleaning may be defined as a secondary manufacturing process in which a suitable stream of solid particles is propelled with sufficient velocity against a work surface to cause a cleaning or abrading action when it comes in contact with the workpiece. As indicated in the definition, blast cleaning may be employed for a variety of purposes. Ordinarily, it is considered as a method for removing sand from castings, burrs or scale from forgings, mill products, or heat treated parts; to promote machinability, and to minimize the possibility of interference in actual operation. In addition to this use, blast cleaning also produces an excellent surface for industrial coatings. All these objectives are often accomplished in the one operation.
This SAE Recommended Practice provides uniform procedures for using the standard shot peening Almen strips reported in SAE J442. Standard Almen strips are used to establish saturation, determine intensity, monitor repeatability of the shot peening machine operations, and can be used to predict a desired result on a part. It is recommended that the standard Almen strip A be used for intensities that produce arc heights of 0.10 mm A (0.004 in A) to 0.60 mm A (0.024 in A). For intensities below 0.10 mm A (0.004 in A), the standard N strip is recommended, and for intensities above 0.60 mm A (0.024 in A), the standard C strip is recommended. Use of SAE 2597 Computer Generated Shot Peening Saturation Curves is voluntary, existing shot peening processes that do not take advantage of computer generated saturation curves need not be changed to meet the requirements listed herein.
This SAE recommended practice provides some procedure for determining shot peening coverage and relating coverage to part exposure to the media stream. Effectiveness of shot peening is directly dependent on coverage. Either incomplete or excessive coverage can be detrimental to fatigue strength and life.