Flashcards on Statistical Analysis of Machine Maintenance Data
Statistical Analysis of Machine Maintenance Data Explained
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Reliability and Maintenance Analysis
12 cards
Card 1
Question: What statistical parameters should be calculated for TTF, TTR, TBF and Availability in a global reliability analysis?
Answer: Mean (M), Standard deviation (SD), Minimum (Min), Maximum (Max), and percentages (%) where appropriate.
Card 2
Question: How is TBF (Time Between Failures) computed from failure history data?
Answer: TBF = TTF (operating time until next failure) + TTR (time to repair/unavailable time).
Card 3
Question: How is Availability calculated from TTF and TBF?
Answer: Availability (%) = (TTF / TBF) × 100, the percentage of time the machine is operating.
Card 4
Question: What auxiliary cumulative columns are recommended to analyze machine lifetime from failure data?
Answer: Accumulated TTF (operating time scale) and Accumulated TBF (global time scale).
Card 5
Question: Why compute a failure rate λ and how is it commonly expressed in this analysis?
Answer: To quantify failures over time; it can be expressed as failures per unit time, for example λ every 100 hours.
Card 6
Question: What is the aim of the ageing analysis in machine reliability?
Answer: To determine whether a machine shows ageing (end of useful life), and if so, when ageing begins to estimate maximum useful life (in total or operating
Card 7
Question: Why are sequential sample tables (every 50, 20, 15 values) used in ageing analysis?
Answer: To perform small-sample statistical checks across the lifetime to detect trends or changes (ageing) that might not appear in aggregate statistics.
Card 8
Question: What types of graphs are recommended to support the detection of ageing?
Answer: Graphs plotting sequential sample statistics (e.g., mean TTF, TTR, availability over time or accumulated hours) to visualize trends from maturity to a
Card 9
Question: How should the start of ageing be reported when detected?
Answer: Indicate the approximate operating hours and total accumulated hours (from accumulated TTF or TBF) when the machine enters the ageing stage.
Card 10
Question: What should the final 'Conclusions' sheet include after analysis of each machine?
Answer: A summary table of significant parameters, an assessment of ageing (not noticeable, early stage, or strong ageing) with the ageing start if detected,