Process Reliability Punch List


What is the issue for process reliability?-

 

How to resolve the issue of process output variability?

 

Typical findings from process reliability analysis:

The punch list for making a process reliability plot for analysis:

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
                                                             production

 

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
29.6% of the losses are between the demonstrated line and the nameplate line

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: 
116,126 – (25,897+35,759) = 54,470 MT/year

 

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
47.3% of the losses are between the demonstrated line and the nameplate line

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 Output/Problems

·         Six Sigma

·         Coefficient of Variation

·         Production Reliability Example With Nameplate Ratings

·         Key Performance Indicators From Weibull Production Plots

·         Production Nameplate Rating

·         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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Last revised 10/26/2008