KPP202 Antti Salonen Maintenance. An introduction

Transcription

1 KPP202 Antti Salonen Maintenance An introduction

2 What is maintenance? Definition (SS-EN 13306): Combination of all technical, administrative, 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.

3 Maintenance retain in Maintenance restore to Preventive maintenance Corrective maintenance Condition based maintenance Predetermined maintenance Scheduled, continuous or on demand Scheduled Deferred Immediate

4 Maintenance activities Cleaning Lubrication Condition monitoring (indirect maintenance) Adjustments Reconditioning Parts exchange (preventive or corrective) Modifications

5 Condition based maintenance Condition 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.

6 Condition based maintenance

7 Condition monitoring Some common condition indicators: Vibrations (e.g. in bearings) Particles (e.g. in gearbox oil) Sound (levels and/or frequencies) Cracks, fractures or wear Increased temperatures Electrical effects, such as resistance, conductivity

8 Why maintenance? Equipment owner Dependability? $ Maintenance

9 Dependability Availability Reliability Is the equipment stable and functioning? Maintainability How easy is it to maintain the equipment? Maintenance supportability How efficient is the maintenance organization?

10 Preventive maintenance M PM MTBM PM Operating MTBM PM Operating Down for PM

11 Corrective maintenance MTBM CM MTBF Operating M CM MTTR MTBM PM MTBF Operating Actual repair time

12 Corrective maintenance MTBF MTW MTTR MTBF Operating Operating MTW A MLDT Total time, down for CM

13 Operative availability MTBM MDT MTBM Operating M MTW Operating M CM M PM MTW A MLDT Down for maintenance

14 Dependability Availability Factors: Reliability Maintainability Maintenance supportability Measures: MTBF M MTW Technical system Organization

15 Cost How to choose Total maintenance cost Cost of PM Cost of lost production Cost of CM Best economical solution Amount of maintenance

16 The economical iceberg Visible costs Hidden losses Personnel Material Overhead Cost of poor maintenance Poor dependability and capacity Waste of time and resources Through inefficient processes Lack of teamwork and communication Easy to measure Limited profit potential Often not measured High profit potential

17 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 accidents Loss of Production (maintenance indirect cost) Maintenance Direct Cost Volume Price Reduce Cost Increase Revenue Profit

18 Fault characteristics Faults Faults Regular faults Time Irregular faults Time

19 Fault development Condition Condition With PF-interval Time Without PF-interval Time

20 Approaches Predetermined maintenance Condition based maintenance Predetermined maintenance or condition based maintenance Run to failure (Corrective maintenance)

21 Maintenance economy

22 Maintenance economy Calculate 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: 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:-

23 Calculation Fault distribution Time RTF Predetermined PM CBM Exchange per year 1/4 1 1/4 Direct maintenance cost 0,25 x ( x 20 x 450) x 4 x 450 0,25 x ( x 4 x 450) Indirect maintenance cost 0,25 x 20 x x ,25 x 4 x Total: :-/year 87100:-/year 21775:-/year

24 Life cycle economy Money 100% lifetime Income LCP LIA Aquisition cost LAC Operations cost LSC Time

25 LCC/LCP LCC = LAC + LSC LAC Development Acquisition Etc LSC LOC (Life Operations Cost) LMC (Life Maintenance Cost) LTC (Life Termination Cost) LCP = LIA LCC LIA Life Income Availability

26 Influencing LCC Life phase 1.Idea 0 2.Specification 1 3.Construction 10 4.Purchasing Operations Discarding ---- Cost factor Maintenance aspects Reliability Maintainability PM requirements Spare part prices Spare part availability Standardization Competence requirements Documentation Tool requirements Support availability Etcetera

27 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