Efficient Plant May 2022 - 6

column | implementations
Design-in
Maintainability
Dr. Klaus M. Blache
Univ. of Tennessee Reliability
and Maintainability Center
(RMC)
T
Remaining Life-Cycle Cost
Reduction Opportunity After
Each Equipment Phase
35%
20%
15%
3%
5%
HE WORDS maintenance and
maintainability are often used
interchangeably. Maintenance is the
performance of fixing or replacing an asset.
Maintainability is a designed-in parameter.
As shown in the graph, by the time a
machine is built, you've lost more than 95%
of the possibility for life-cycle cost reductions.
Maintainability needs to be implemented in
the planning phase.
Statements from the Principles of Maintainability
Design (B.S. Blanchard in NASA
RCM Guide ) include:
Great maintenance procedures cannot
overcome poor equipment design.
All parts and components are replaced
eventually, so design for that time.
Label key components, show flow
direction, and provide decision-making
information.
Design systems so failures are obvious.
Reduce the opportunity for human error
during maintenance.
Repair is mainly a human activity.
Design maintenance tasks to fit human
limitations.
Design repair tasks, alignments, and
adjustments for minimum tear down.
Accessibility should enable easy access
to maintenance points and largely reduce
maintenance time.
I teach thirty categories for Design for
Adapted from B.S. Blanchard in NASA RCM Guide
By the time a machine is built (construction),
you've lost more than 95% of the possibility
for life-cycle cost reductions.
Maintainability. A sampling of four categories
that you should be considering are:
Standardization: Minimize the proliferBased
in Knoxville, Dr. Klaus M. Blache is
director of the Reliability & Maintainability
Center at the Univ. of Tennessee and a
research professor in the College
of Engineering.
Contact him at kblache@utk.edu.
6 | EFFICIENTPLANTMAG.COM
MAY 2022
ation of parts, material (hoses, mechanical/
electrical components, valves), tools, and
processes/procedures. Have you eliminated
the need for special tools? Are spare parts
common coded to reduce excess spares?
Accessibility: This defines the ease at
which a component can be accessed for
intended maintenance. Is the repair space
large enough? Are reach distances adequate?
Are guards or other interfering items easily
and safely removed? Can parts that break
frequently be easily removed?
Visual Aids: Good visual controls facilitate
fast and accurate maintenance. Do you
use bar coding on your assets and in your
spare-parts storage? Are lubrication points
identified (color coded and alpha-numeric)
with type of lubricant, amount, and frequency?
Are all maintenance points visually
accessible from the side or end of machine
and have line-of-sight inspection capability?
Troubleshooting: Is key information
quickly available, such as pressure, amperage,
fluid flow, component identification? Do
you have self-checking features and/or builtin
test capability? Can hydraulic, electrical,
and other systems be easily traced throughout
the machine? Are your engineers trained
to include design-for-maintainability
concepts into machinery and equipment
designs? Do you have checklists on key
items for areas such as routine maintenance,
accessibility, and hydraulic/mechanical/
electric system design? Are there DfM
(Design for Maintainability) expectations
written into your purchasing specifications,
i.e., statements such as, " all hydraulic lines
should be replaceable in 10 to 15 minutes. "
Not designing in maintainability adds
to MTBF. By spending a little more initially
(versus cutting costs), how maintenance is
performed can be significantly improved
over the life of the asset.
There are numerous reliability and
maintainability activities that should be
done during the planning phase through
the operating and maintaining-equipment
phases. If you're looking for checklists as
they apply to the life cycle of machinery
and equipment and actions to be followed,
refer to the Reliability and Maintainability
Guideline for Manufacturing Machinery and
Equipment (SAE Order No. M-110.2). EP
Planning
Concept/
preliminary
design
Final design
Construction
Operating &
maintaining
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