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Scoring  Scoring is deep, multiple scratches caused by sliding at the rolling contact surface in the presence of foreign particles usually found on ball, roller, and raceway surfaces. (Refer to Table 302 and Table 303 for limits.) 
Skidding  Skidding is excessive slipping between balls or rollers and raceways. Skidding is evidenced on roller bearings by a burnished or frosted ring around the rollers and/or raceways, on ball bearings by a speckled wear pattern, or by a burnished or frosted ring on balls, and by burnished or irregular frosted or smeared areas on the inner race. Skidding is cause for rejection. (See Figure 306 and Figure 307.) 
Spalling  Spalling is exhibited by irregular shaped cavities of flaked-out metal from a raceway or rolling element surface with jagged bottoms caused by rolling contact fatigue. Spalling is cause for rejection. (See Figure 308.) 
Fractures  See Cracks. 
Raised metal  Raised metal not specifically covered by description or illustration is not acceptable. 
Burrs  See Raised metal. 
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Inspection
20-00-02/70-00-01
Table 301.  Bearing Component Inspection Criteria Definitions and Limits (Cont)
Term  Definition (Description of Defect)
Roller end wear  Roller end wear may appear as circular scratches, burnishing, scuffing, frosting or pitting.
The roller end inspection criteria is based on the DN value of the bearing where D is the bore in millimeters and N is the speed of the rotating ring.
For example, a 40 millimeter bore bearing with rotating inner ring speed of 20,000 rpm equals 800,000 DN. If the DN value is greater than 700,000, the following guidelines shall be followed.
1.  Roller ends which exhibit wear of 0.0001 inch (0,00254 mm) or more measured from the unworn surface are cause for rejection. Exceptions to this criteria are:
.  
Wear on the center portion of the roller end caused by debris between cage and roller as shown in Figure 309 is acceptable.

.  
Roller end patterns that are eccentric irrespective of wear depth are cause for rejections. (See Figure 310.)

.  
Excessive pitting conditions as shown in Figure 311 are cause for rejection.

.  
Excessive scuffing patterns as shown in Figure 312 are cause for rejection.

.  
Other roller end patterns are shown in Figure 313 and Figure 314 and are subject to the above criteria.

2.  
For bearings with a DN value of less than 700,000, all criteria are the same as for bearings with DN above 700,000 except that the wear limit is 0.0002 inch (0,00508 mm).

3.  
Cage defects, which are cause for rejection, include the following.

.  
Flaking, peeling, and blistering of silverplate (Figure 315).

.  
Grossly uneven wear of silverplate on pilot surface (Figure 315).

.  
Cage pocket wear that has worn through silverplate. Figure 316 shows a marginal case that should be considered as cause for rejection when specified in inspection instructions of applicable chapter/section/subject for a particular bearing.

.  
Cracked cages as shown in Figure 317 are not acceptable.

.  
Bent or broken cages are not acceptable.

.  
Purple to black discoloration is acceptable on bearing cages unless silver plated surfaces show evidence of heavy chemical attack, i.e., pitting, surface roughness, or exposed base metal.

 

Inspection
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20-00-02/70-00-01
Table 302.  Inspection Criteria for Acceptance of Bearing Component (Rings and Rolling Elements) Defects*
　
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