4. Replacement Problem
• When should a product or service be
replaced?
– Economic/ Financial considerations (when cost of
maintenance becomes higher than cost of
replacement)
– Other considerations
• Replace on complete breakdown
• Replace after n failures
• Replace at periodic intervals
• Etc.
5.
6. A thought experiment
• When a product or service deteriorates gradually, how to
decide when to replace?
• How to mitigate the risk of sudden failure? (Your car engine
stalls)
• How to handle a scenario where people rather than
products are involved? (When one of your best people’s
performance goes down, what to do?)
• What to do if a product goes out of fashion/ obsolete
compared to other new products? (When to replace your
Sony Walkman?)
7. General approach to solve
replacement problems
• Analyze the failure or performance reduction
pattern over time
• Assess probability
• Assess costs of replacement
– Actual cost
– Cost of replacement (labour etc.)
– Cost of disruption (opportunity loss, lost
production, lost orders, learning curve)
8. Scenario 1: Maintenance cost
increases over time
Purchasing Maintenance Maintenance Maintenance Scrap
Price Cost Cost Cost Value
11. Sudden Failure Scenario
• We have to look at probabilities of failure and
cost of failure
• Individual replacement
– Replace on failure
– Attrition of employees also falls under this
scenario
• Group replacement
– When one individual in a set of products fails,
replace the entire group