on Maintenance Reliability

Introduction

This article is a highly simplified overview of Equipment Maintenance Strategies. Its objective is to categorize the types of maintenance approaches for the lay person. Sometimes, explaining the basics using simple terminologies, initiates dialogues with others that are outside of our field of expertise. And as such improve collaboration between teams. How about making this accountant who somewhat controls the maintenance budget, understand what maintenance is really about? On the other hand, that same accountant can educate us on their work practices.

Crow-AMSAA Analysis Overview

Crow-AMSAA Plots have a variety of names, such as Reliability Growth Plots or Duane Plots. The term “Crow” comes from Dr Larry H. Crow, who enhanced James T. Duane’s pioneering launch of this methodology, which was developed in the early 1960s (1). Crow successfully applied the method in the US Army Materials System Analysis Activity (AMSAA). The technique has blossomed into large amounts of new applications in industry such as but not limited to:

• Making reliability more visible and manageable hence contributing to Reliability Improvement Programs,

• Monitoring Design Optimization and Quality Performance,

• Catastrophic or adverse event occurrence predictions and trends which in essence are the objective of this article.

In practical terms, The Crow-AMSAA technique involves plotting, most commonly, cumulative failures vs cumulative time on a log-log scale resulting in straight line plots (2). The line slope value (or Beta value) indicates improving, deteriorating, or constant failure occurrences. Due to the straight-line nature of the plots, future failure forecasts can be estimated. In plain words, based on the current trend, when is the next failure expected to occur? This method handles mixed failure modes, so it is, therefore, suitable for the complex nature of the generating units. [Read more…]