Maintenance Resources

Sunday, April 25, 2010

Shortfalls in Spare Management and cost saving

Spare part management is one of the most crucial but neglected side in most of the organization. It directly contributes to cost . For establishing a good spare part management systems it is require to establish a good and effective maintenance management throughout the plant. Beside this, it is not possible to establish a cost effective, optimum spare management system.

I have a big spare room with a huge inventory cost. Some of the materials are not using for last one year. I don’t know when it will fail. I spend a lot of time to search the correct spare. I have material inward and outward register but hardly we are following it (I too know that it is a Herculean task and so I left it on GOD….and so on……..

Generally a spare management in most of the middle and small companies runs with following defects.
1.    Force deterioration of the machine spares in exists which means  MTBF data is not reliable  for the spares.
          If you go through net, you will find individual MTBF data for most of the items like PLC components, sensor etc. Those data are based on product reliability (multiplication of individual component reliability to determine product reliability) which is lucrative and far from our reality, almost like mileage declaration of a car by manufacturing companies. You will get a idea but it will not exactly match with your individual data because your driving condition is not known by manufacturer. So, you can get close to the manufacturer claim if you go close to their considered ideal situation i.e. force deterioration should be removed.

2.    Lack of  predictive observation to plan for the spares
         Just a week ago one operator told me about some flaws. I adjusted it temporarily and forget to take action to eliminate the causes of the flaws. It will repeat again with a bang and then I have no spare…just can curse myself for not taking action on that time. So, it is require to noting down the flaws before to forget and it need to be available to general so that they can give a maintenance request to do the opportunity maintenance

3.    Maintain the spare level comes under regular maintenance persons who are running to do their breakdown or PM jobs. For them they really don’t have time to think ‘bout spare level, reorder level (and due to verities of spares it is not possible to implement 100 % visual control).

So, instead of appoint one dedicated spare control person I prefer to hand it over to store for good accountability. they can issue it on request , maintain the track and intimate when it reaches to predefined re-order level very easily because it is none but their daily business (matching to their regular job profile).

For optimization of spare management, following tools are used (This is just a list for information and you can find a lot of topics on individual items if you are really interested on it)

Approach                                                 Basic of classification             Major application
ABC analysis --------------------------- Annual sales volume-------------- Stock control
HML  (High, medium, low value) ---------Spare unit price---------------  Delegation of purchase power
VED (Vital, essential, desirable) approach---Part criticality ---------------  Storage point
XYZ analysis -------------------------------inventory value-------------- Obsolescence control
VEIN (Vital, essential, important, normal)---Equipment criticality------------Standby decision
FAN (Failure analysis)---------------------Design of spare ---------------Reliability engineering
GOLF (Govt. controlled, ordinary and
locally available, Foreign procurement) ----  Source of spare ------------- Purchase strategy (Lead-time and                                                                                                               reorder point)
3-D  ------------------------------------ Cost, criticality and availability ----All of the above uses

AND here is a tinny and easy calculator to decide for high value spares whether it require in spare or not.

Spare Parts Management Calculator by World Class Manufacturing

And last here is formula to define economic order quantity (EOQ)

D: The demand for widgets in quantity per unit time. Demand can be thought of as a rate.
Q: The order quantity. This is the variable we want to optimize. All the other variables are fixed quantities.
C: The order cost. This is the flat fee charged for making any order and is independent of Q.
h: Holding costs per widget per unit time. If we store x widgets for one unit of time, it costs us x.h.
A good CMMS will be time and cost saving approach…Isn’t it ?  :)


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