Bathtub Curve and MTBF
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A Real-World Bathtub Curve
MTBF is a reliability metric, especially for products or systems exhibiting failures in a shape of a bathtub curve. Information on MTBFs supports decision making for engineering development and service operations in management and planning.
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A bathtub curve generally represents three phases of product failures, including an early phase, a normal service life phase, and a wear-out phase. For a real product, we may or may not observe all three phases. For an MTBF estimation purpose, we expect a constant failure rate during a product's service period.
1. Field return data fit in a bathtub curve
This is an example of how a set of real field return data look like after being processed and presented in a failure rate plot. It can be observed that the data fit a bathtub curve showing an early and then a constant failure rate phase of the product in this example.
2. The original data
​If you need to know whether your products, systems or assets in operation also exhibit a bathtub failure behavior, or if you simply need MTBF info to be extracted from field data for some reason, we can help, We provide a free service for a preliminary analysis. You can click here to contact us.
​A Real-World Bathtub Curve:
1.Field return data fit in a bathtub curve
2.The original data
3.Identified early failures
4.MTBF
5.Reliability growth
​A Nevada chart and a Pareto histogram plot are used to present the original field return data of this example.
Some observations of the data include:
1-The data set represents a total of 245 units and 284 failure reports returned from field;
2-Data were collected across a time span from Mar.2014 to Jun.2015;
3-There appeared an early failure mode;
4-A major percentage of either no failure found (NFF) or failures yet to be determined (TBD) or isolated is included in the data set.