Design of Experiments (DoE) and the Analysis of Variance (ANOVA) techniques are economical and powerful methods for determining the statistically significant effects and interactions in multivariable situations. DoE may be utilized for optimizing product designs, as well as for addressing quality and reliability deficiencies. Within the DoE framework, the practitioner may explore the effects of a single variable or analyze multiple variables. [Read more…]
The Failure Reporting and Corrective Action System (FRACAS) is a closed-loop process whose purpose is to provide a systematic way to report, organize and analyze failure data. Implementation of a FRACAS has increasingly become commonplace within an industry. The requirement for implementation of some type of FRACAS within a DoD program was first established in 1985 with MIL-STD-2155. However, in 1995 that standard was reestablished with no changes to content as a handbook, MIL-HDBK-2155, and was recommended as guidance. Today, multiple software solutions exist that provide all the functionality required of a FRACAS. [Read more…]
After the system has been drawn in block diagram form, subsystem and component reliability goals and targets are established. This is a common practice in the development of complex systems, particularly when different design teams or subcontractors are involved. Reliability allocation involves setting reliability objectives for components or subsystems in order to meet a system reliability objective and should occur in the initial stages of design or prior to designing major system upgrades. [Read more…]
This week in our CRE Test Prep class/webinar we covered the Advance Statistics section of the CRE Primer, and I felt great that we stayed an hour more going over these though topics.
One of the topics was Hypothesis Testing.
Let me share some of the questions that arose during that section. [Read more…]
Last week during our CRE Test Prep class, we were covering the Basic Statistics section in the CRE Primer and had several questions regarding Confidence Limits for Reliability.
All of them were fair questions, and when students are asking these types of questions, the class gets better… [Read more…]
In a recent LinkedIn post a fellow Reliability Engineer is asking the Reliability Engineering community in how to prepare for the CRE exam. Rapidly everyone is recommending books, study groups, and training courses. My recommendation to anyone taking the CRE exam is to be very familiar with your approved ASQ calculator. Here is a link that I found in [Read more…]
During design and development, Reliability Engineers often receive reliability parameters in many forms. The most common reliability parameter is the mean time to failure (MTTF), which can also be specified as the failure rate (this is expressed as a frequency or Conditional Probability Density Function (PDF)) or the number of failures during a given period. [Read more…]