REGISTER NOW! August 1, 2022. FREE 1–Hour Virtual Uptime Elements Introduction

The Reliability Engineering Toolbox

What is Weibull analysis?

Weibull analysis is the tool of choice for most reliability engineers when they consider what to do with age-to-failure data. It uses the Weibull distribution which says mathematically that reliability, R(t) = e-(t/h)^b where t is time, h is a scale factor know as the characteristic life (most of the Weibull distributions have tailed data and lack an easy way to describe central tendency as the mode≠median≠mean, however, regardless of the b-values, which is a shape factor, and all of the cumulative distribution function values pass through the h value at 63.2% which thus entitles it to be know as the single point characteristic life).

Why use Weibull analysis?

The Weibull distribution is so frequently used for reliability analysis because one set of math (based on the weakest link in the chain will cause failure) described infant mortality, chance failures, and wear-out failures.

When to use Weibull analysis?

Use Weibull analysis when you have age-to-failure data. When you have age-to-failure data by component, the analysis is very helpful because the b-values will tell you the modes of failure which no other distribution will do this! When you have age-to-failure by system, the b-values have NO physical significance and the b-, h-values only explain how the system is functioning-this means you loose significant information for problem solving.

Where to use Weibull analysis?

When in doubt, use the Weibull distribution to analyze age-to-failure data. It works with test data. It works with field data. It works with warranty data. It works with accelerated testing data. The Weibull distribution is valid for ~85-95% of all life data, so play the odds and start with Weibull analysis. The major competing distribution for Weibull analysis is the lognormal distribution. For additional information read The New Weibull Handbook, 5th edition by Dr. Robert B. Abernethy and use the WinSMITH Weibull and WinSMITH Visual software for analyzing the data (both software are bundled for a reduce price as SuperSMITH).

These definitions are written by H. Paul Barringer

Return to Reliability Tools

Paul Barringer

Paul Barringer, is a reliability, manufacturing, and engineering consultant. His worldwide consulting practice involves, reliability consulting, and training with a variety of discrete and continuous process manufacturing companies and service industries.

He has more than fifty years of engineering and manufacturing experience in design, production, quality, maintenance, and reliability of technical products. His experience includes both technical and bottom-line aspects of operating a business with an understanding of how reliable products and processes contribute to financial business success.

Upcoming Events

August 9 - August 11 2022

MaximoWorld 2022

View all Events
80% of newsletter subscribers report finding something used to improve their jobs on a regular basis.
Subscribers get exclusive content. Just released...MRO Best Practices Special Report - a $399 value!
Reliability Leader Fluid Cleanliness Pledge

Fluid Cleanliness is a Reliability Achievement Strategy as well as an asset life extension strategy

MaximoWorld 2022 Conference Austin Texas

Connect with leading maintenance professionals, reliability leaders and asset managers from the world's best-run companies who are driving digital reinvention.

“Steel-ing” Reliability in Alabama

A joint venture between two of the world’s largest steel companies inspired innovative approaches to maintenance reliability that incorporate the tools, technology and techniques of today. This article takes you on their journey.

Three Things You Need to Know About Capital Project Prioritization

“Why do you think these two projects rank so much higher in this method than the first method?” the facilitator asked the director of reliability.

What Is Industrial Maintenance as a Service?

Industrial maintenance as a service (#imaas) transfers the digital and/or manual management of maintenance and industrial operations from machine users to machine manufacturers (OEMs), while improving it considerably.

Three Things You Need to Know About Criticality Analysis

When it comes to criticality analysis, there are three key factors must be emphasized.

Turning the Oil Tanker

This article highlights the hidden trap of performance management systems.

Optimizing Value From Physical Assets

There are ever-increasing opportunities to create new and sustainable value in asset-intensive organizations through enhanced use of technology.

Conducting Asset Criticality Assessment for Better Maintenance Strategy and Techniques

Conducting an asset criticality assessment (ACA) is the first step in maintaining the assets properly. This article addresses the best maintenance strategy for assets by using ACA techniques.

Harmonizing PMs

Maintenance reliability is, of course, an essential part of any successful business that wants to remain successful. It includes the three PMs: predictive, preventive and proactive maintenance.