SMS Spares Management Software

1. 1 SMS – Spares Management Software

2. 2 The software allows for calculation of the optimal stock size for both the repairable and the non-repairable parts cases. Optimization criteria considered are the ones listed in the figure (I will explain briefly each one of them shortly). For the non-repairable case, we have considered cost minimization and interval reliability of the stock as possible criteria for optimization. In the case of repairable parts, all four criteria are applicable and are considred in SMS. After selecting the criteria to be used, and using the models presented in detail in the paper in the proceedings, SMS gives us the optimized stock size (or spares requirement). Interval reliability of the stock is (go to slide) Instantaneous reliability of the stock is (go to slide)…..of course, interval reliability, as it involves a longer interval, is more demanding than instantaneous reliability. Cost minimization is the most common optimization criteria, and relates to finding the stock size that minimizes costs per unit time, including stockholding and shortage penalty costs. Availability is defined as (go to slide)The software allows for calculation of the optimal stock size for both the repairable and the non-repairable parts cases. Optimization criteria considered are the ones listed in the figure (I will explain briefly each one of them shortly). For the non-repairable case, we have considered cost minimization and interval reliability of the stock as possible criteria for optimization. In the case of repairable parts, all four criteria are applicable and are considred in SMS. After selecting the criteria to be used, and using the models presented in detail in the paper in the proceedings, SMS gives us the optimized stock size (or spares requirement). Interval reliability of the stock is (go to slide) Instantaneous reliability of the stock is (go to slide)…..of course, interval reliability, as it involves a longer interval, is more demanding than instantaneous reliability. Cost minimization is the most common optimization criteria, and relates to finding the stock size that minimizes costs per unit time, including stockholding and shortage penalty costs. Availability is defined as (go to slide)

3. 3 Repairable Spares

4. 4 Criteria for Decision Making

5. 5 Scenario

6. 6 Results: Repairable Parts

7. 7 Reference Case -case study results were based on data from a fleet of Hydro One Power Transformers -reference case -variation of parameters were performed for each case and results have been summed up in the form of graphs-case study results were based on data from a fleet of Hydro One Power Transformers -reference case -variation of parameters were performed for each case and results have been summed up in the form of graphs

8. 8 Repairable Instantaneous Reliability -both calculate stock reliability at any moment in time -H1 uses replacement time of 0.001 yr (negligible) -> very similar to instantaneous reliabiltiy case -recall: add up all failure probabilities up to a certain point -> means that reliability more than its actual value -but adding a minor replacement time decreases reliability -the two minor changes cancel each other out and the results between the two models are extremely similar -more spares -> reliabilities increase & results become more similar because the failure probabilities at higher levels are even less probable with more spares so cut-off at level six is more adequate-both calculate stock reliability at any moment in time -H1 uses replacement time of 0.001 yr (negligible) -> very similar to instantaneous reliabiltiy case -recall: add up all failure probabilities up to a certain point -> means that reliability more than its actual value -but adding a minor replacement time decreases reliability -the two minor changes cancel each other out and the results between the two models are extremely similar -more spares -> reliabilities increase & results become more similar because the failure probabilities at higher levels are even less probable with more spares so cut-off at level six is more adequate

9. 9 Case studies: Fume fan shaft, blast furnace in a steel operation: non-repairable part, decision support Power train component, haul trucks: repairable parts, multiple criteria Frigate control system: supportability interval

10. 10 1. Fume fan shaft – steel mill

11. 11 How many spares – Fume fan shaft?

12. 12 I will now present a case study constructed with data coming from a mining operation in South America. Data used is for a component in the propulsion system (power train) of haul trucks.I will now present a case study constructed with data coming from a mining operation in South America. Data used is for a component in the propulsion system (power train) of haul trucks.

13. 13 6,600 operating hours per truck per year (average fleet utilization) Preventive replacement policy at 9,000 operating hours in place Here is a brief description of the data utilized.Here is a brief description of the data utilized.

14. 14 Based on estimations provided by maintenance personnel Estimated at MTTR = 452 operating hours

15. 15 This summary presents the data that was entered into the SMS software, where optimal results were obtained accordingly to all four criteria.This summary presents the data that was entered into the SMS software, where optimal results were obtained accordingly to all four criteria.

16. 16 It is interesting to see that the result varies depending on the criteria selected. In this case, as the shortage costs are known (quantifiable) it seems appropriate to go with this answer, of 14 spares. Note that the associated reliability for the stock (instantaneous – or fill rate) is very high. This is due to the fact that, as downtime costs are large compared to stockholding costs, it is better to have more spares than to accept the small risk of having a shortage. In other applications, shortage costs are very difficult to quantify, so usually in that case we will be interested in achieving certain reliability.It is interesting to see that the result varies depending on the criteria selected. In this case, as the shortage costs are known (quantifiable) it seems appropriate to go with this answer, of 14 spares. Note that the associated reliability for the stock (instantaneous – or fill rate) is very high. This is due to the fact that, as downtime costs are large compared to stockholding costs, it is better to have more spares than to accept the small risk of having a shortage. In other applications, shortage costs are very difficult to quantify, so usually in that case we will be interested in achieving certain reliability.

17. 17 4. Frigate control system – supportability intervals (S.I.)

18. 18 Case Study – Supportability Interval (S.I.)

19. 19 Case Study (S.I.) / 2

20. 20 Case Study (S.I.) / 3

21. 21 Thank you Thank you very muchThank you very much