problem in the supply of spare parts, is
planning, executing, the required spares
planning. Spare parts requirement requires
articulate planning procedural lead time, and
the correct required spares.
Drawing/specification should be confirm to
standards. The Purchase order should given
correct description, code no: drawings and
amendments if any in due course. The supplier
should be a A class supplier.
The major problem in spares part management is
identification and procurement of exact match.
in India, the
technicians on the road are not aware of exact
specifications and try to fit the materials
available with them to make quick money. Standard
workshops are the best solution. They procure and
manage spares parts from genuine source and exact
Identification of spare parts is not a problem, but
keeping inventory of the spares is the biggest problem.
How do you identify the correct spares, and do allow to
keep excess inventory. A good planning for spares, with
proper drawing/identification/requirement of spares is
required. Forecast the required quantity and keep
The identification of parts are not a problem. now a
days most of the international manufacturers have their
own EPC.With the correct VIN in automoblles and the so
called Serial and Model nos in Industrial or,Marine
applications along with a bit of technical knowledge
about the product the identification factor is no
problem. On the contrary the intelligent stock control
by setting the correct re-order
levels, interchangeability, procurement span, back to back
orders to sustain the required stock status are the basic
things to be observed in parts management. Forecasting
ability to a great extent is a boon
Do not depend upon the
principals only for all your parts.You should have
contacts with your fellow deales,distributors and even
with the fleet owners.
You can count on them on an emergency to save time and
though reduce the down time.
Major problem is human error. If you do not have a
controller meticulous with scrutinizing said
assets/inventory, then no matter the system; it will all
be a bust.
I completely agree all the comments above, I also feel
along Planning, Execution & control of spares you should
also have well defined & Robust Data Management for
better Procurement cycle.
Spare parts does not have consumption prevision, this is
Since budgeting is the most important thing in providing
the spare, we believe that the clear identification what
spares and how much spares need to be stocked which
shall be aligned with the R&M reliability target
performance will take the most major problem. Moreover
if we don’t have system in place which providing the
complete data base of SPIR (Spare Part Interchanged
Record) started from list of parent unit equipment with
complete associated spares
Any Spares parts should be procured with the help of Machine
Catalogue by mentioning assembly no./sub assembly no./
Try to procure from OEM or develop in market. In
Stores, parts should be stored according to Machines
with respective Part nos.
A Complete Data
Bank of Spares should be maintained with storage
locations. Any Spares should have clearly defined
level of storage and condition of storage.
Let us understand that spare parts planning does not
coincide with the normal planning of material
requirement. Spares are required to tide away breakdown
of machines. To plan for spares of any machine, 1.
drawings. 2. cataloge 3.Part nos. 4. suppliers of parts.
To stock spares since we cannot predict the breakdown we
should be able to stock critical parts required for the
machine. Spares maintenance is utmost important for the
time spent on breakdown will lead to loss. One more
aspect is that there should be reliable supplier for
spares, and service centers of any machine should hold
spares for the on-going supplied machines.
what are you using as a benchmark to determine a "Spare
I did not understand MTBF. I was only concerned with
stocking of spares which is unique compared with the
stocking of regular materials. Please let me know more.
There is no levels for spare parts, it is difficult, I
do not how you gauge the levels of keeping spare. Please
note for any equipment 80% of the spares have to kept.
You do not when there will breakdown, and what quantity
you require. Only you open up the required machine, and
examine you'll understand. You should have all the
spares. My experience in working in Steel Pant
maintenance spares were foretasted by the respective
user department, and they predicted the spares
In spare parts first we have to identify as per there
category Insurance spare , critical spare , general
consumable spare in first ins. spare we have to keep it
may be used or not and also critical spare , in case of
cons. spare we can standardization and keep minimum
spare which may be common for other equipment,
i belive it too. We should get an maintenance material
forecast. But to get it is not easy. Could you tell us
how difficult was it?
If we are talking about spare parts, the major problem
will appeare in the critical spares which we doesn't use
often and after certain period of time it will be
obsolete and should get rid of it in the same time these
are the large peices that cost much, so it's forecast is
I believe Marcelo is on the right track ...
Bit I would take this several steps further ...
The term "MTBF" is the Mean Time Between Failure
analysis which is performed on all major assemblies or
This is not a new process but rather a very tried and
I would suggest you meet up with your Engineers and have
them assist you in performing the analysis of which
component, sub-assembly or assembly will have the
shortest life cycle
There is no reason for you attempt to carry 1 unit as a
spare for every 1 unit in the filed for possible
replacement, besides the inventory investment would be
Also, in performing your MTBF analysis, review those
items which an extensive lead time - you may chose to
make the investment in this material ...
When creating a "Spare Inventory", the financial
investment is for the contractual period of time -
suffice it to say - if you have a contract with Company
X for the next 7 years - then you must either have on
hand or have access to this inventory.
A financial controller will understand this - and will
make the proper reserves for said inventory
Spares parts management should be linked to proper bill
of material ( BOM )of the equipment. Each item in that
BOM should be properly identified as criticality on
operation point of view with lead time to get on hand.
Based on which; Material planner can plan for ordering
which will in turn can directly have impact on inventory
i have already listened about mtbf, but never seen a
pratical application. We have thousands of itens. Could
you send me a example? How to select the itens?
we are creating our BOM and the plan is to creat a
material forecast. Thanks for the suggestion.
spares comes in raw categories and there are huge
quantities with different sizes whether it is mechanical
components , Electrical, Electronics components. that
all should be properly codified and to be stored with
their part number wise. lets take an example of
Resistance or capacitor in electronic industries. it is
quite typical to manage the inventory with part name. So
there should be properly codification with its
identification than only it can easly trace out in
is a simplified version of the term "MTBF"
but in my obersversation it works well
and this where the conversation with the
Engineers becomes critical
And to PP Kumar comments - agreed - the more
classification - the better
And regarding lead times ...
if this link (back to Procurement) is not
dynamic - then it will send off "false
or worse "notice to buy will be always late"
Mean time between failures (MTBF) is the
predicted elapsed time between inherent
failures of a system during operation.
MTBF can be calculated as the arithmetic
mean (average) time between failures of a
system. The MTBF is typically part of a
model that assumes the failed system is
immediately repaired (mean time to repair,
or MTTR), as a part of a renewal process.
This is in contrast to the mean time to
failure (MTTF), which measures average time
to failures with the modeling assumption
that the failed system is not repaired
(infinite repair rate).
The definition of MTBF depends on the
definition of what is considered a system
failure. For complex, repairable systems,
failures are considered to be those out of
design conditions which place the system out
of service and into a state for repair.
Failures which occur that can be left or
maintained in an unrepaired condition, and
do not place the system out of service, are
not considered failures under this
definition. In addition, units that are
taken down for
scheduled maintenance or inventory control, are not
considered within the definition of failure.
For each observation, downtime is the instantaneous
time it went down, which is after (i.e. greater
than) the moment it went up, uptime. The difference
(downtime minus uptime) is the amount of time it was
operating between these two events.
MTBF value prediction is an important element in the
development of products. Reliability engineers /
design engineers, often utilize Reliability Software
to calculate products' MTBF according to various
methods/standards (MIL-HDBK-217F, Telcordia SR332,
Siemens Norm, FIDES,UTE 80-810 (RDF2000), etc.).
However, these "prediction" methods are not intended
to reflect fielded MTBF as is commonly believed. The
intent of these tools is to focus design efforts on
the weak links in the design.
There are many variations of MTBF, such as mean time
between system aborts (MTBSA) or mean time between
critical failures (MTBCF) or mean time between unit
replacement (MTBUR). Such nomenclature is used when
it is desirable to differentiate among types of
failures, such as critical and non-critical
failures. For example, in an automobile, the failure
of the FM radio does not prevent the primary
operation of the vehicle. Mean time to failure (MTTF)
is sometimes used instead of MTBF in cases where a
system is replaced after a failure, since MTBF
denotes time between failures in a system which is
repaired. MTTFd is an extension of MTTF, where MTTFd
is only concerned about failures which would result
in a dangerous condition.
1.^ Jones, James V., Integrated Logistics Support
Handbook, page 4.2
2.^ Colombo, A.G., and Sáiz de Bustamante, Amalio:
Systems reliability assessment – Proceedings of the
Ispra Course held at the Escuela Tecnica Superior de
Ingenieros Navales, Madrid, Spain, September 19–23,
1988 in collaboration with Universidad Politecnica
de Madrid, 1988
"B10d Assessment - Reliability Parameter for
Electro-Mechanical Components"]. TUVRheinland.
Retrieved 16 April 2012.
Jones, James V., Integrated Logistics Support
Handbook, McGraw–Hill Professional, 3rd edition
(June 8, 2006), ISBN 0-07-147168-5
As I have stated before ...
this is where the Engineers have to come to the
it would be ludcrious for anyone to start a process
whereby a 1:1 spares relationship needs to be
also, P P Kumar has this right - categories components,
subassemblies, major assemblies into critical MTBF mode
I believe, even though the cost would be greater - it
would be "smarter" for us to carry sub-assmblies, et al
rather than try to carry each individual component.
So let me ask this, when was the last time you actually
tried to perform troubleshooting on a sub-assembly which
may have >1000 components?