Process Reliability
Punch List |
Figure 1: 366 Days Of Production In A Weibull Plot |
Figure 2: Zoom On Step Section
Of The Curve |
Figure 3: Fit The Demonstrated Production Line |
Figure 4: Sum Gaps To The Left Of The Demonstrated Production Line |
Total Production = 868,199.1 (Metric Tons) Production Line = Eta 2,775.538, Beta 16.76324 Nameplate Line = None Total Reliability (8.5-100%): Loss = 116,126 (Metric Tons) ßEqual
to 116,126/2,775.538 = 42 days Process Reliability (%) = 8.5 8.5-11.8%: Loss = 1,187 (Metric Tons) ßTransition zone 11.8-61%: Loss = 25,897 (Metric Tons) 61-64%: Loss = 2,981 (Metric Tons) ßTransition zone 64-91.8%: Loss = 35,759 (Metric Tons) 91.8-97%: Loss = 26,787 (Metric Tons) ßTransition zone 97-100%: Loss = 23,515 (Metric Tons) Without a nameplate line all losses look
like reliability problems! |
Figure 5: Nameplate Line |
Figure 6: Gap Analysis Between Data Points And Both Trend Lines |
Total Production = 868,199.1 (Metric Tons) Production Line = Eta 2,775.538, Beta 16.76324 Nameplate Line = Eta 2,880.606, Beta 27 Total Reliability (8.5-100%): Loss = 116,126 (Metric Tons) Process Reliability (%) = 8.5 8.5-11.8%: Loss = 1,187 (Metric Tons) 11.8-61%: Loss = 25,897 (Metric Tons) 61-64%: Loss = 2,981 (Metric Tons) 64-91.8%: Loss = 35,759 (Metric Tons) 91.8-97%: Loss = 26,787 (Metric Tons) 97-100%: Loss = 23,515 (Metric Tons) Efficiency + Utilization (Production - Nameplate): Loss = 48,859 (Metric Tons) Hidden factory losses = 116,126 + 48,859 = 164, 985 MT/year. The hidden factory losses represent 164,985/2775 = 59 days of normal output 70.4% of the losses are between the demonstrated line and the
data points, and |
Figure 7: Probit-3 Plot By Grade |
Figure 8: Upper Right Hand Corner Data Magnified |
Figure 9: Demonstrated Production Lines By Grade |
Figure 10: Gap Analysis Between Data Points And Both Trend Lines Restated |
Total Production = 868,199.1 (Metric Tons) Production Line = Eta 2,775.538, Beta 16.76324 Nameplate Line = Eta 2,880.606, Beta 27 Total Reliability (8.5-100%): Loss = 116,126 (Metric Tons) Process Reliability (%) = 8.5 8.5-11.8%: Loss = 1,187 (Metric Tons) 11.8-61%: Loss = 25,897 (Metric Tons) ßTransition zone, a hidden factory 61-64%: Loss = 2,981 (Metric Tons) 64-91.8%: Loss = 35,759 (Metric Tons) ßTransition zone, a hidden factory 91.8-97%: Loss = 26,787 (Metric Tons) 97-100%: Loss = 23,515 (Metric Tons) ßDowntime Removing the grade production
rates shows the Reliability Losses are:
Efficiency + Utilization (Production - Nameplate): Loss = 48,859 (Metric Tons) Hidden factory losses = 54,470 + 48,859 = 103,329 MT/year. The hidden factory losses represent 103,329/2775 = 37 days of normal output Based on the recognition of slower grades in production the losses are restated: 52.7% of the losses are between the demonstrated line and the
data points, and |
Figure 11: All Losses Shown On
One Sheet With Grade Considerations |
Want More Process Reliability Information?-
· Special Cause Variations, Common Cause Variations, and Process Reliability Plots
· Summary Of Process Reliability
·
Process Reliability Punch List
· Production Reliability Example With Nameplate Ratings
· Key Performance Indicators From Weibull Production Plots
·
Process Reliability Plots With
Flat Line Slopes
· Process Reliability Line Segments
· Automating Monthly Weibull Production Plots From Excel Spreadsheets
·
Papers
On Process Reliability As PDF Files For No-charge Downloads
- New
Reliability Tool for the Millennium: Weibull Analysis of Production Data
- Process
Reliability and Six-Sigma
- Process
Reliability Concepts
Download a copy of this problem of the month involving process reliability plots with probit analysis by clicking here.
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