ML20100R385

Intervenor Exhibit I-53,consisting of Gv Luther 830920 Memo to DE Ellis Re Peening of Diesel Crankshaft Fillets

ML20100R385
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	10/01/1984
From:	Luther G AFFILIATION NOT ASSIGNED
To:	Ellis D AFFILIATION NOT ASSIGNED
References
OL-I-053, OL-I-53, NUDOCS 8412170398
Download: ML20100R385 (3)

Text

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hTEROFFICE AMM MEMORANDUM  ?,%.21 11600.37 SUS ECT DIESEL CRANXSHAFT FILI,ITS, DATE SEPTEMBER 20. 1983 PEENING FRCM GARY V. T.,U . . '

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preliminary analysis perfcrmed by FaAA (as of this

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date) finds that the lower 1/3 of the reentry fillet at the crankshaft pin function is the most critical area with respect to crankshaft failures The reasons given are:

(1) High stress at loading (the crankshaft may  ;

be near a harmonic at its leaded running l speed.  !

4 (2) A residual stress (deter =.w.ed by x-ray l diffraction) at the fillets caused apparently )

by machining. g (3) Surface finish at the fillets. Although the f i

finish does not appear to be rough to the naked eye (or by feel), I have seen scanning electr n

, microscope photographs of cracks in initial stages of propagaticn. The cracks appear to I be initiating at one of the radially machined l "vallers" of the fillet. 9 In order to reduce the residual tenstle stresses at the fillet (and also to reduce the degree of valley f alignment with the pri=ary tensile stress planes), we have h

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specified peening to be perfor=ed (at TOI). I!

y However, review of the as-received cranks found that  ;

they were inadequately peoned at locations of interest (to FaAA) l l e.g. the lower 1/3 of the fillet. FaAA recerrended that the peening be redone by a " Metal Improvement Co." , specialists ,

in controlled peaning. <

l MIC already performs peening to crankshaft fille:s for other diesel manufacturers.

i j MIC's equipment was transported to the site and the peening was performed in a building erected to house the crankshaft.

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MIC reported that the fatique life of a properly peened crankshaf t can be increased by 100t by proper peening.

CC checks - Peenine 1005 peer.ing is defined as areas where the surface is totally dimpled. They have invented a "peenscan method" to verify 1005 peened surf aces. The process utilt.es an ultraviolet solution (the process is somewhat si- .lar to a UV magnaflux check) which the UV sensitive solution is applied to the area to be peened. 1005 peening is defined by a total removal of the ultraviolet sensitive solution.

An ultraviolet light is used to verify its remcval.

MIC-CL Conversatices I questioned the MIC engineer on repeening previously peened surfaces and his reply was that peening typically becomes detrimental to f atique life only if the peening abrades a critical sec': ion. Ha also stated that their equipment is designed for accessability and cor.troI and that their operators are experienced enough so that abrasion of peened sections is not a problem.

Attached is a sample of MIC's shot; you will note  !

,f its uniformly round geometry which'is much "better" than commercial cleaning shot. The tape which the shot is attached to is similar to duct tape and is used for masking areas specified as not to be peened.

Overall, I was impressed with the company's control and expertise. The company essentially wrote MIL-S-13155 (which we invoked on the crankshaf t) . MIL-5-13165 is much more definitive overall in the peening process than any SAE spec.ification I have seen. I requested that they send a pr: duct brochure to Boston describing their processes and any data they they have concerning the b .eneficial effects for other applications.

Other applications they cited may be reduction of residual stress on turbine shafts, and reduction of residual tensile stresses where stress cceros an cracki,pq is a concern,

' .A G. ". Luther l p.S. The new crankshafts reentry fillet geometry is cggh bett,er than the old one.

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