Do you have derating & safety margin manual 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 as reliable as your customers deserve.

Derating and safety factors 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?

Well, first of all, they are boring! They tend to add cost and weight to a product. Moreover, the calculations take data and time to accomplish.

Reliability is just one of many objectives for a development team and often is not the single most important one. Thus the constraints of cost, time to market, or functional capability tend to consume the resources available. Manuals take time and resources to assemble so often have a lower priority.

Create a System of Use for the Manual

One way to incorporate the use of design guidelines is to create reinforcing processes around the use and benefits of using the manual’s guidelines. Initially the process requires a few case studies to demonstrate that following the guidelines saves

• total costs, despite the increased cost of components,
• time to market by avoiding last-minute redesign work, and
• product functionality by creating a more robust capability of each unit.

The idea is to celebrate those teams correctly deploying and using the manual. Building a set of ‘see it works here’ stories to share within the organization provides incentives to invest in meeting the design guidelines as the benefits become clearer.

A second system to reinforce the first comes in the form of reviews and questions. The design team responds to what is measured. If our team is only measured on time to market, despite our understanding of the importance of cost and reliability, we will focus on time to market.

As with key performance indicators, what we measure collectively and which measures dominant the focus are what matter. It is vital to ensure that the system of reviews, the questions posed, and the measures tracked include the longer term results that include reliability performance. However, short-term aspects are important too. A design review should not simply focus only on the cost of the assembled components, but include questions about reliability, durability, and lifecycle costs.

Derating and safety design guidelines are specific topics for review and discussion. Good questions to ask are ‘Did we, as a design team, meet every element of the guidelines?’ and ‘Which elements of the design do not meet the guidelines and what is the impact?’

Support with Appropriate Infrastructure

Regularly telling the story that using the guidelines is good for the customers and for the business is one step in getting the guidelines implemented. Another is the tactical reinforcement of the expectation and review of the actual calculations and decision-making process. Another element is the support of the ease of use of the guidelines. Here are some proactive actions to take:

• Provide training and education support for anyone involved with the implementation of the guidelines.
• Provide tools to determine tradeoffs between cost, time to market, customer satisfaction, etc. when meeting or not meeting the guidelines.
• Provide visibility for the teams that achieve reliability objectives without heroic last-minute or reactive measures.

Creating a set of guidelines for derating and safety margins is the easy part. Getting the manual off the shelf and into the design is not. Senior management support certainly helps, yet alone it is not sufficient. You need to create the reinforcing processes that encourage, check, and reward implementation of the guidelines.

Bio:

Fred Schenkelberg is an experienced reliability engineering and management consultant with his firm FMS Reliability. His passion is working with teams to create cost-effective reliability programs that solve problems, create durable and reliable products, increase customer satisfaction, and reduce warranty costs. If you enjoyed this articles consider subscribing to the ongoing series at Accendo Reliability.