Your Reliability Engineering Professional Development Site
Find all articles across all article series listed in reverse chronological order.
In the previous article, What is Reliability Optimization, we defined the concept. One of the elements of optimization is identifying which elements of a system to focus improvement efforts on.
Simply improving every element of a design may provide an overall improvement of reliability performance.
Given constraints such as time or funding, selecting the specific few elements that would provide the most improvement is key. [Read more…]
On occasion, you and the team sit down to review the design.
The idea is to check the design for any issues with the combined wisdom of the people involved. Or, it may be a status update for the entire team providing a focus on the most important issues and action items.
The review may involve all departments, such as marketing, operations, supplier management, and the design team.
It may involve just you and the electrical engineer in a private meeting. In either case, it is a review and a chance to illuminate salient reliability issues and form a consensus on the appropriate action. [Read more…]
It is easy to understand why the term HALT (Highly Accelerated Life Test) is so tightly couple to the equipment called “HALT chambers” systems. Many do not think they can do HALT processes without a “HALT Chamber”. Many know that Dr. Gregg Hobbs, who coined the term HALT and also HASS (Highly Accelerated Stress Screens), spent much of his life promoting the techniques and was also the founder of two “HALT/HASS” environmental chamber companies. [Read more…]
Delivering the best reliability performance within the various constraints imposed.
Without constraints such as budget, time to market, customer expectation, product functional capabilities, and product weight, you certainly could design and deliver a highly reliable product.
There always are constraints.
In the Oliver Wendall Holmes poem, The One Hoss Shay, the deacon procures the strongest oak, the supplest leather, and the best of best materials. Cost was not a constraint. And the shay lasted 100 years to the day.
If the technology permits there may be stronger or more durable components available for a price, yet cost is often a limiting factor. [Read more…]
A plan is a guide or roadmap for intended action.
A reliability plan is also a collection of specific tasks and milestones and enhanced with a rationale to allow the entire team fully understand their role accomplishing the reliability objectives.
The plan is a way to achieve the desired business objectives. Meaning the product is reliable enough to meet customer expectations, minimize warranty expenses, and garner market acceptance. The plan is just a plan, it is the accomplishment of the tasks, the decision which improves the design, the signals monitored that stabilize the supply chain and assembly process, that make the difference.
A plan without action is not worth the effort. [Read more…]
In some circumstances, it is desirable to ensure the system continues to operate even if there is an internal failure. An aircraft navigation system should be able to operate even if an internal dc-dc regulator fails, for example.
Not everything within some systems benefits by being fault tolerant.
For example, a failure of a cabin reading light over a passenger seat is not critical to the safe operation of the aircraft, thus is likely not created to be fault tolerant. One criterion to determine what should be fault tolerant is the criticality of the function the system provides.
This also applies to specific subsystems within a system allowing some elements to be created fault tolerant and others within the system not. [Read more…]
Do you have one in your organization? Is it used regularly?
If not, your organization’s products are likely not as reliable as they should be. You are shipping products that are not as robust nor reliable as your customers deserve.
Derating and Safety Factors, defined earlier, provide a means to select components or create design features that have sufficient margin to accommodate variation in use and strength over time.
So why are these tools routinely ignored or given only fleeting attention? [Read more…]
Many reliability engineers have discovered HALT will quickly find the weaknesses and reliability risks in electronic and electromechanical systems from the capability of thermal cycling and vibration to create rapid mechanical fatigue in electronic assemblies. Assemblies that have latent defects such as cold solder or cracked solder joints, loose connectors or mechanical fasteners, or component package defects can be brought to a detectable, or patent, condition by which we can observe and potentially improve the robustness of an electronics system.
Fault tolerance is a system that is reliant to the failure of elements within the system. It also may be called a fail safe design.
A fault tolerant system may continue to operate just fine, after one of the power supplies fails, for example. Or it may operate in a reduced or degraded state.
Other systems may have a ‘limp home’ condition, allowing the system to save critical data or allowing you to drive to a safe place to change a flat tire. [Read more…]
Key Performance Indicators (KPIs) are measurable values related to essential business objectives.
A KPI provides a means to monitor the performance of a specific function.
In larger organizations, with sales & marketing, research & development, operations, supply chain and other teams working to bring products to market, each department has a specific role. [Read more…]
Concurrent engineering is a common approach that pairs the development of the product design and it’s supporting manufacturing processes through the development process.
Design engineers may require the creation of new manufacturing processes to achieve specific material properties, component performance, or mechanical, electrical or software tolerances. [Read more…]
Let’s discuss the Arrhenius model. One thing you didn’t know about is that you may already be an expert in it. How could that be you ask? You have probably used it many times at home. [Read more…]
Traditional electronics reliability engineering began during the period of infancy in solid state electronic hardware. The first comprehensive guide to Failure Prediction Methodology (FPM) premiered in 1956 with the publication of the RCA release TR-1100: “Reliability Stress Analysis for Electronic Equipment” presented models for computing rates of component failures. “RADC Reliability Notebook” emerged later in 1959, followed by the publication of a military handbook know as that addressed reliability prediction known as Military Handbook for [Read more…]
A product or system’s actual reliability performance is a function of the design, assembly, and use.
Decisions made during design predominately create the inherent reliability capability performance.
The selected components, manufacturing, transportation and installation all can add variability and errors to the product, often reducing the actual reliability performance.
The use conditions and maintenance add another layer of variability, again reducing reliability capability. [Read more…]
Next week is RAMS – the Reliability and Maintainability Symposium. A multitrack 3.5-day conference with classes, tutorials, paper sessions, a small trade show, plus many of you – peers, colleagues, and friends in the reliability world.
The conference is hosted by 9 professional societies and organized by a group of about 50 or so volunteers from those societies (I was an active member of the RAMS management committee for many years). [Read more…]
