maintenance - mdhzoomin.idt.mdh.se/course/kpp202/ht2010/le7asn100923...condition based maintenance...
TRANSCRIPT
What is maintenance?
• Definition (SS-EN 13306):– Combination of all technical, administrative, and managerial actions during the life cycle of and managerial actions during the life cycle of an item inteded to retain it in, or restore it to, a state in which it can perform the required function.
Maintenance
Maintenance
Corrective Preventive
’retain in’ ’restore to’
Corrective maintenance
Preventive maintenance
Deferred Immediate
Condition based maintenance
Predetermined maintenance
Scheduled, continuous or on
demand
Scheduled
Maintenance activities
• Cleaning
• Lubrication
• Condition monitoring (indirect maintenance)
• Adjustments
• Reconditioning
• Parts exchange (preventive or corrective)
• Modifications
Condition based maintenanceCondition Based Maintenance is defined as: ”Preventive maintenance based on performance and/or parameter monitoring and the subsequent actions.”
and shall serve the following purposes:
• to determine if a problem exists in the monitored item, how serious it is, and how long the item can be run before failure, and
• to detect and identify specific components in the items that are degrading and diagnose the problem.
Condition based maintenance
Condition monitoring
Some common condition indicators:
•Vibrations (e.g. in bearings)
•Particles (e.g. in gearbox oil)•Particles (e.g. in gearbox oil)
•Sound (levels and/or frequencies)
•Cracks, fractures or wear
•Increased temperatures
•Electrical effects, such as resistance, conductivity
Why maintenance?
Equipment ownerEquipment owner
Maintenance
$?Dependability
Dependability
Availability
Maintenance supportabilityMaintainabilityReliability
Is the equipment stable and
functioning?
How efficient is the
maintenance organization?
How easy is it to maintain the
equipment?
Preventive maintenance
MPM
MTBMPM MTBMPM
Down for PM
Operating
MTBMPM
Operating
MTBMPM
Corrective maintenance
MCM
MTTRMTBMCM
MTBFMTBMPM
MTBF
Actual repair time
Operating
MTBF
Operating
MTBF
Corrective maintenance
MTBFMTTRMTW
MTBFMTBF
Total time, down for CM
MTWA MLDT
Operating Operating
MTBF
Operative availability
MTBMMDT
MTBMMTBM
MCM MPM
M
MTWAMLDT
MTW
Operating
MTBM
Operating
Down for maintenance
Dependability
Availability
Maintenance supportabilityMaintainabilityReliability
MTWMMTBFMeasures:
Factors:
Technical system Organization
How to chooseCost
Cost of PM
Total maintenance cost
Amount of
maintenance
Cost of CM
Cost of lost production
Best economical solution
PersonnelMaterial
OverheadVisible costs
Easy to measureLimited profit potential
The economical “iceberg”
Cost of poor maintenance
Poor dependability and capacity
Waste of time and resourcesThrough inefficient processes
Lack of teamwork and communication
Hidden losses Often not measuredHigh profit potential
Successful Maintenance
• Minimize breakdowns
• Minimize downtime
• Minimize rework
• Minimize inventory
• Minimize spare parts
• Minimize overtime
• Reduce cost of maintenance system by extending useful life of the asset
• Reduce the cost of employing reactive maintenance
• Improve reliability & availability
• Improve plant performance
• Support new market opportunities
• Enhanced and consistent product quality to secure, or even increase the customers
• Minimize overtime
• Minimize accidents
Loss of Production (maintenance indirect
cost)
Maintenance Direct Cost Volume Price
Reduce Cost Increase Revenue
Profit
Fault characteristics
Faults Faults
Regular faults Irregular faultsTime Time
Fault development
ConditionCondition
Time TimeWith PF-interval Without PF-interval
Approaches
Predetermined maintenance
Run to failure(Corrective maintenance)
Condition based maintenance
Predetermined maintenance or condition based maintenance
Maintenance economy
Maintenance economyCalculate the best economic alternative (RTF, Predetermined PM, or CBM) for the impeller on the pump. The pump is essential in the production and hence, there are no natural downtime for maintenance. If the impeller breaks, the impeller axel is also damaged and has to be exchanged. The impeller condition may be monitored and prognosticated through vibration monitoring.
DATA:DATA:
Impeller lifetime: 1-7 years
Downtime cost (lost production): 20000:-/h
Maintenance time when planned stop: 2 men, 4 h
Maintenance time when unplanned stop: 2 men, 20 h
Wages: 450:-/h
Impeller cost: 3500:-
Cost for impeller axel: 1500:-
Calculation Fault distribution
RTF Predetermined PM CBM
Exchange per year 1/4 1 1/4
Direct maintenancecost
0,25 x (3500 + 1500 + 2 x 20 x 450)
3500 + 2 x 4 x 450 0,25 x (3500 + 2 x 4 x 450)
Indirectmaintenance cost
0,25 x 20 x 20000 4 x 20000 0,25 x 4 x 20000
Total: 105750:-/year 87100:-/year 21775:-/year
Time1 2 3 4 5 6 7
Life cycle economyMoney 100%
lifetimeIncome
Time
Operations cost
Aquisition cost
LAC
LCP
LSC
LIA
LCC/LCP
LCC = LAC + LSC•LAC
•Development•Acquisition•Acquisition•Etc
•LSC•LOC (Life Operations Cost)•LMC (Life Maintenance Cost)•LTC (Life Termination Cost)
LCP = LIA – LCCLIA – Life Income Availability
Influencing LCC
Life phase Cost factor1.Idea 02.Specification 1
Maintenance aspectsReliability
MaintainabilityPM requirementsSpare part prices
3.Construction 104.Purchasing 1005.Operations 10006.Discarding ----
Spare part pricesSpare part availability
StandardizationCompetence requirements
DocumentationTool requirementsSupport availability
Etcetera…
Further reading:
Life cycle costing - theory, information acquisition and application (Woodward, 1997)
Terotechnology, (Belak, 2004)
My next lecture: Dependability (Thursday, 7/10)Bring calculators
Download/print ”Dependability” from course home page
Terotechnology, (Belak, 2004)