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Reliability Growth Projections
A Powerful Planning and Management Tool
An effective reliability growth test planning and management strategy can contribute greatly to successful product design and development through its impact on
the ability of the design/development team to meet desired reliability goals on time and within the project budget.
RGA 6 provides full support for the reliability growth test planning/management strategy and data analysis methodology
developed by Dr. Larry Crow. These techniques provide useful metrics to support decision-making, including the demonstrated MTBF through testing, the growth
in MTBF that will be achieved through implementation of corrective actions, the maximum potential MTBF that can likely be achieved for the product design and estimates regarding
latent failure modes that have not yet been uncovered through testing.
Analysis with Crow Extended Model
Traditional reliability growth analysis models allow you to analyze data from tests where the corrective actions are incorporated during the test
(test-fix-test). However, in actual practice, fixes may be delayed until after the completion of the test (test-find-test) or you may implement some fixes during the test while delaying others
(test-fix-find-test). With the Crow Extended model (new formulation, available only in RGA 6
PRO), you can analyze time-to-failure data with additional information on failure modes and the reliability growth
management strategy, including:
- Failure Mode Identification
and Classification
- A = No corrective
action
- BD = Delayed corrective action
(aka "B" modes)
- BC = Corrective action during the test
(aka "C" modes)
- Effectiveness Factors to estimate the
reduction in a failure rate for the mode once delayed fixes have
been implemented.
Analysis with Crow Extended (reliability growth projection) model.
[Click to Enlarge]
Reliability Growth Projection Plots/Charts
and Calculations
Reliability growth projection results can be presented in graphical
plots/charts and via the Quick Calculation Pad (QCP). Plots/charts include:
- Growth Potential MTBF (or Failure Intensity):
The MTBF/Failure Intensity demonstrated during the test, the projected MTBF/Failure Intensity after the implementation of delayed fixes and the maximum MTBF (or minimum Failure Intensity) that is achievable given the current management strategy (growth potential).
- This information is also available in pareto (bar) charts that compare the demonstrated, projected and growth potential MTBF or Failure Intensity.
- MTBF (or Failure Intensity) by Failure Mode:
Pareto (bar) charts that display each failure mode ranked by MTBF or Failure Intensity.
- Failure Mode Strategy: Pie chart that displays the breakdown of failures by type: Type A failures will not be corrected;
Type BD - Unseen failures have not yet
appeared in testing but are estimated from the analysis; Type BD - Remain
failures will remain in the system because corrective actions are
not 100% effective and
Type BD - Removed failures
will be removed from the system with the implementation of delayed corrective actions.
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Plots and Charts to illustrate reliability growth projection analysis results.
[Click to Enlarge] |
These reliability growth projection results are also available from RGA's Quick Calculation Pad (QCP).
QCP with Projection calculations displayed.
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Version
7
