Return centered spares (RCS): A method for quantifying the benefits of spares
Koskinen, Jesperi (2025)
2025
Konetekniikan DI-ohjelma - Master's Programme in Mechanical Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
Hyväksymispäivämäärä
2025-09-09
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202509099097
https://urn.fi/URN:NBN:fi:tuni-202509099097
Tiivistelmä
For rare, high impact events it is not immediately clear whether having a spare makes financial sense. In this thesis, a method is developed for quantifying the financial impact of spare acquisi tion. This is estimated with Monte Carlo simulation method to see what costs are expected to happen with and without a spare on a production line.
This thesis uses a constructive research method. First, literature review is done for building the appropriate method, and second, the method is tested with a case study. During the theoret ical part consists of mathematical background on probability, reliability engineering and business intelligence. In these sections, along with the main background theory, subprocesses were intro duced which are used in the RCS process itself. These processes include RCM, LCC and Monte Carlo simulation.
After the theory section, the proposed RCS process is introduced. In RCS, knowledge of failure modes that is gained from the RCM analysis is used in Monte Carlo simulation to build a LCC model. This knowledge consists of what failures can happen and what are their consequences. Then random failures are simulated based on the distributions on each failure mode to build a possible failure scenario for a production line. Then, the costs of the failures are calculated using the net present value method. Averaging different random scenarios together allowed to estimate the expected costs with and without a spare.
An additional look was done to know what the most important variables and inputs are regard ing having a spare. This was done via looking at the Monte Carlo simulation and seeing what the biggest cost drivers are. Also, it was inspected when the optimal timing is for acquiring the spare. This was done via also looking at the Monte Carlo simulation and seeing how the costs develop over time. The spare acquisition should be done at a point when it provides greatest economic benefit.
In case study the RCS method was used for an asset in a fiberline. This was done together with an OEM, which wanted to quantify the benefits of having a spare. During the case study it was confirmed that RCS is a useful applicable method for achieving the goals of quantifying the spare benefit, understanding the most important variables and assessing the optimal timing for acquiring the spare.
This thesis uses a constructive research method. First, literature review is done for building the appropriate method, and second, the method is tested with a case study. During the theoret ical part consists of mathematical background on probability, reliability engineering and business intelligence. In these sections, along with the main background theory, subprocesses were intro duced which are used in the RCS process itself. These processes include RCM, LCC and Monte Carlo simulation.
After the theory section, the proposed RCS process is introduced. In RCS, knowledge of failure modes that is gained from the RCM analysis is used in Monte Carlo simulation to build a LCC model. This knowledge consists of what failures can happen and what are their consequences. Then random failures are simulated based on the distributions on each failure mode to build a possible failure scenario for a production line. Then, the costs of the failures are calculated using the net present value method. Averaging different random scenarios together allowed to estimate the expected costs with and without a spare.
An additional look was done to know what the most important variables and inputs are regard ing having a spare. This was done via looking at the Monte Carlo simulation and seeing what the biggest cost drivers are. Also, it was inspected when the optimal timing is for acquiring the spare. This was done via also looking at the Monte Carlo simulation and seeing how the costs develop over time. The spare acquisition should be done at a point when it provides greatest economic benefit.
In case study the RCS method was used for an asset in a fiberline. This was done together with an OEM, which wanted to quantify the benefits of having a spare. During the case study it was confirmed that RCS is a useful applicable method for achieving the goals of quantifying the spare benefit, understanding the most important variables and assessing the optimal timing for acquiring the spare.