Which Weibull parameter is associated with wear-in failures?

The Weibull distribution is often used in reliability engineering to model life data and failure rates, and it is characterized by three parameters: eta (η), beta (β), and gamma (γ). Among these parameters, beta is particularly significant for identifying the failure types associated with a given process.

Wear-in failures, which occur during the initial period of an equipment's lifecycle, are typically associated with decreasing failure rates as the most unreliable components fail early on. This behavior is represented by a beta parameter value of less than 1 in the Weibull distribution. A beta value less than 1 indicates that the failure rate decreases over time, which aligns with the concept of wear-in, where the product stabilizes after an initial period of early failures.

Eta represents the scale parameter, which defines the characteristic life of the distribution, while gamma describes a location parameter that allows for shifting the distribution along the time axis to account for failures that may not start at zero time. Delta is not a standard parameter in the Weibull distribution.

Thus, recognizing that wear-in failures are characterized by early-life failures and a decreasing failure rate clearly indicates that the correct association is with the beta parameter.