Why is proper lubrication important?

After experiencing numerous axle hub failures on new production, a customer called upon VNC to help determine the root cause and solution.

The very next day, VNC traveled to the customer’s site in order to examine the failed axle hubs and review all of the known facts.

While keeping an open mind to all possible root causes, all early indications pointed towards a problem involving inadequate lubrication, however, upon reviewing the site’s assembly and lubrication processes no irregularities were observed.

With inadequate lubrication seemingly ruled out, several failed bearings, as well as the mating components, were disassembled and taken back to VNC’s inspection lab for a more in depth examination.

Forensic Examination:

Although most of the bearings were badly destroyed and difficult to inspect, the forensic examination continued to point towards inadequate lubrication as the root cause of failure.

During the examination the bearing fragments from the raceways and rollers consistently demonstrated severe discoloration and scoring. At such an early stage in their field life, such signs would not occur under proper lubrication conditions.

In addition to the failed bearings, sampling was completed on the current bearing inventories and all bearings were found to meet specifications.

The Hypothesis:

With all components meeting design specifications, no signs of external contamination, and inadequate lubrication seemingly ruled out, the team turned towards the one observation that could not be explained.

Despite the numerous failed axle hubs on new production, every single failure was occurring on the curb side of the axle. If a product defect were causing failures in the field, this affinity to one side of the axle would not occur. Instead the failures should exhibit a random pattern among the assembly locations.

With renewed focus on the curb side of the assembly line, the assembly and lubrication processes at the customer site were reviewed once again in greater detail.

The Solution:

Several days later after an in depth investigation of the lubrication portion of the assembly line, the customer was finally able to identify the root cause for the recent axle hub failures.

With the renewed focus on inadequate lubrication, it was discovered that the lubrication machinery used on the curb side of the assembly line was improperly modified in order to decrease the time for lubrication.

This modification was found to directly cause less lubrication to be applied to the curb side axle hubs. With less lubrication, the bearing components were not receiving ample lubrication in order to protect the bearing components and perform properly.

Once the machinery was returned to normal operating conditions, the curb side axle hubs were once again receiving a proper amount of lubrication during assembly. With the root cause corrected, the axle hub failures were eliminated.

Contact VNC Bearing today to find out how we can help you.