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Developing a Motor Bearing Regreasing Strategy
H. Ron Elliott, Lubrication Engineer, Castrol
North America
The objective is to design a motor relubrication program that
will ensure motor maintenance is done on the basis of chronological
need. The below relube program is based on the assumption of a
simple Preventative Maintenance approach rather than Predictive
or Proactive Maintenance programs, which the manager can explore
later. The main steps to accomplish this objective are to:
1. Document and identify the motors in a relevant way
2. Determine the "Relube Interval" and lubricants required
3. Determine the last and next scheduled relube dates
4. Set up a relube schedule
5. Keep the schedule updated
I would recommend Excel to tabulate this data, although any good
database program could be used. Excel information is easy to manually
manipulate; and for those skilled, much of the maintenance of
the database might be automated. At a minimum, I would recommend
creating the below fields to track data:
· Motor ID (location, identification, etc.)
· Motor Info (HP, manufacturer, frame type)
· Lubricant (recommended bearing lube)
· Date Installed (if available)
· "Relube Interval" (the recommended time between relubes)
· "Last Relube" (date motor was last lubed)
· "Next Relube" (date motor to be next relubed)
· Comments (list any special actions or conditions)
The most critical Excel field for determining the order of the
spreadsheet will be the "Next Relube" date. When completed, the
spreadsheet should list the motors in order of when pending maintenance
is required. Maintenance would then simply address the motor relube
program in the sequential order of the spreadsheet list.
Step 3 is where the greatest difficulty lies in setting up a
new program. Some special conditions and exceptions to be considered
are:
· Motors past due for relube: List them at the top of the spreadsheet
in order of lateness or criticality so they will be first done.
In the "Next Relube" field, enter the date as to when the motor
should have been relubricated, even if that date is past.
· Motors of unknown date of "Last Relube": Assume that half
the "Relube Interval" has passed and set "Next Relube" date accordingly.
Consequently, enter the "Last Relube" date field with the date
one-half the "Relube Interval" previous. (Example: if today's
date is July 21, 2003 and the "Relube Interval" is 4 years, enter
July 21, 2001 for the "Last Relube" date; enter July 21, 2005
for the "Next Relube" date.)
· Motors that have been installed for a period less than the
"Relube Interval": Set the installation date as the "Last Relube"
date, and schedule the "Next Relube" date accordingly.
· Permanently Lubed Bearings: Mark "No action"
· Special exceptions: Note unusual situations, such as vertical
motors that use oil in the bell housing, and grease in the shaft
bearing.
As mentioned, arrange the spreadsheet in ascending order based
on the field of "Next Relube". As each motor is relubricated,
update the "Last Relube" and "Next Relube" fields. Then use the
Excel "Sort Function" on the "Next Relube" field to reorder the
spreadsheet. This way, the next required relube actions would
always be the top rows.
After acquiring and tabulating the necessary information to create
the schedule, the maintenance manager can begin implementation.
After he initiates the program in Step 4 he needs to be diligent
and keep the schedule updated (Step 5). This will be critical
to making the system work. The Relube schedule will become a "living"
document by reason of frequent updating and should always reflect
the order in which maintenance is to be done from the current
date onward.
The schedule should not be clouded by having to wade through
previous, closed out maintenance. In other words, the list should
have each motor listed only once, in the order of when scheduled
for "Next Relube".
Each motor will list the last time it was lubed, the next time
it is scheduled for relube, and the "Relube Interval", along with
other pertinent motor data.
Another important part of successful implementation of the program
will be to determine what maintenance relube equipment is needed
to accomplish the duties.
In establishing the program, be careful to ensure that management,
maintenance, and affected workers are educated to the need of
the program and its goals as early as possible. Many good programs
- even those with management blessing - have failed because of
ruffled feathers, prejudice, or just resistance to new programs
or personnel
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to this Readers Challenge.
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