Typical Characteristics of
• Large in numbers and varieties
• Absence of Specifications
• Erratic consumption / No pattern
• Sourcing constraint
• High Prices High / non moving Inventory due
to above parameters
• Requirement of Large Space and preservation
• Difficult to dispose off
Initial Approach Comprehensive List With
details of Equipment and Spares
Estimate Requirements based on past
experience for similar equipments
Classify Criticality of Equipments
Classify Spares as Vital, Essential, Desirable
Identify Insurance Spares
Identify High Cost Spares
Identify Durable and Consumable Spares
Decide Frequency for review of Spares for
Based on VED classification and cost of
Spares, decide optimum safety stocks
Fix min, max and reorder levels for
For durable spares, MRP data to be reviewed
by competent engineers to assess
Insurance spares requirement to be initiated
by user and reviewed at high levels
Preservation plan and activity to be chalked
out for durable and insurance spares
Adopt Standardization as follows :
Use Standard drives and couplings
Use standard fasteners with maximum
Avoid fine threaded fasteners wherever possible.
Instead use standard threads with lock washers.
Establish standard range of lubricants for the
Use standard structural shapes ,bearings and
Use standard pipes and tube fittings.
Replace with standard parts whenever non
standard parts become defective.
Among various categories like Routine,
Leverage, Bottleneck and Critical ,Spare
parts fall into category of Bottleneck.
Hence we should have close
relationship with suppliers I.E
Safety stocks pertaining to different
service levels is calculated as K^m
where K is a constant with various
values ranging from 0.7 to2.3 to give
service levels from 75% to 99%
Critical, cheap and frequently used
items will require higher assurance level
and hence higher safety stocks
Non-Critical, expensive and slow
moving parts will have low safety stocks.
Categorization of Spares
Preventive maintenance spares-such as filter
cartridge, rubber parts etc. These are known
as programmed spare parts.
Items with fairly steady and high usage.
Short life items like bulbs, fuses, V-belts,
bearings, switches etc. The aggregate
quantity based on number of machines to be
Low and irregular usage items. Long life
items having fractional usage even annually.
Items required for over-haul. Requirement
per machine per over-haul.
Spare parts Management is to be treated as separate
discipline from normal Inventory Management.
Close cooperation and coordination among Operations,
maintenance and Supply departments is essential to
achieve optimum inventory levels.
Top Management support and encouragement for
calculated risk taking and innovation is a must for
Involvement of smart and knowledgeable engineers for
assessment of requirements, usage/disposal of non-moving
spares, identification of interchangeability of
spares, development of drawings for source development
and preservation norms.