shot peening residual stress - Metal Improvement Company

C H A P T E R T W E L V E
C ONTROLL ING THE PROCESS
50
S P E C I F Y I N G S H O T
P E E N I N G
Figure 12-11 shows a splined shaft (shaded)
installed with two bearings supporting the shaft
inside an assembly. The outboard spline and
adjacent radius would be likely fatigue failure
locations from bending and/or torsional fatigue. In
this case, engineering would specify shot peening
(of the shaft) on the drawing as follows.
• Area "A": Shot peen
• Area "B": Overspray allowed
• Area "C": Masking required
The details on the print should read
• Shot peen splined areas and adjacent radius
using MI-110H shot; 0.006"-0.009" A intensity.
• Minimum 100% coverage in splined areas
to be verified by PEENSCAN ® .
• Overspray acceptable on adjacent larger diameter.
• Mask both bearing surfaces and center shaft area.
• Shot peening per AMS-S-13165
It is important to note that if Non-Destructive Testing is required, NDT should always be performed before
shot peening. The peening process will obliterate or close up small surface cracks skewing NDT results.
Metal Improvement Company has over five decades of experience engineering shot peening callouts.
MIC specializes in the proper selection of shot size and intensity parameters for fatigue and/or corrosion
resistant applications. The worldwide service center locations are listed on the back cover of this
technical manual.
REFERENCES:
12.1 Internal Metal Improvement Co. Memo
www.metalimprovement.com
Figure 12-11 Assembly Drawing of Spline Shaft
Requiring Shot Peening