The Design for Reliability Process for Launching Reliable Products


What is the design for reliability process that importers can follow to make sure that their products don’t fail once in use by customers, even if it’s some time after the sale date?

Since you need products to last at least the length of their warranty period, and probably longer in order to avoid upsetting customers, implementing a DfR approach during your product design and development process makes sense, but what is DfR and what activities does it process include? Read on to find out…


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What is Design for Reliability and its objectives?

DfR is one of the components included under the ASQ’s terminology of DfX: Design for Excellence. This overall approach includes manufacturability, testing, quality, sustainability, and of course, reliability, among others. When designing a product a lot of people forget that when implementing a DfR approach the main objective is to reduce costs by improving the quality and reliability of the product.

Design for Reliability means that you’ll be making the whole product reliable, so this will include a focus on reliability for its parts, design, testing, analysis, and more. (01:08)


What makes an unreliable product?

There are a number of reasons why a product turns out to be unreliable and in today’s world where products tend to be more complex and have more parts than in the past (consider, for example, today’s cars in comparison to those of a couple of decades or more ago) which means there’s more to go wrong. Let’s go through them:

  • A poor product design – the design can make everything unreliable from the start if it’s not done well and could lead to non-compliance, quality and safety issues, or just poor performance that is out of spec.
  • Using low-quality parts – if you include components that were not tested to verify that they can perform to your requirements because they’re a bit cheaper, they’re probably poorer quality. That will build unreliability into the product, as they may end up failing in, say, extreme temperatures or environments. They may work, but not for the long term.
  • Not doing adequate reliability testing – both hardware and software need to be tested during the new product development process up to and during assembly to verify their reliability. By doing so you’re getting peace of mind that the product won’t fail in the field after some time, so it’s dangerous to skip it or not do it thoroughly enough to, say, save on some costs.
  • Not using data to do a Pareto analysis – what percentage failed, passed, or was borderline? What corrective action plan do you have for each area of testing? Without fixing the issues that your testing uncovers you will continue to encounter product failures in the field.
  • Manufacturing issues – a product may have great design, testing, and analysis, but if the manufacturing processes have problems this could still lead to unreliable products. An example is if your manufacturer sources some similar but cheaper components that haven’t gone through testing and validation in order to make some extra profit. The components may do the same job but fail later on which is exactly the opposite we’re looking for from product reliability in the field. In order to iron out possible manufacturing issues, companies with enough budget will run a pre-production run (or pilot run) to assemble 3-500 units and examine the production process. Any problems can be solved before mass production begins, reducing the risk of reliability issues creeping into large volumes of the product.
  • Having an unclear user manual – the user manual needs to give exactly the right instructions. Translated manuals, for example, are at risk of errors which could guide the customer to use the product incorrectly, damaging it or leading to reliability issues and product returns. (04:29)


What are some of the secrets to applying DfR that people need to know about?

Let’s say you have implemented good design, testing, and everything else in place that should give you a reliable product, but your failure rate is still too high. There are 2 key reasons for this that can often be overlooked:

  1. You designed the product with components that are put in a position where they experience high stresses (such as an unexpected load on them while the product is in use). In this case, the stress they’re under must be reduced at the design level in order to reduce product failures.
  2. A lot of components are failing because they’re weak, so stronger components must be used.

‘Derating’ is an engineering approach that can help improve reliability in cases like these. An example to illustrate this is a resistor that is supposed to run at 10W, but you run it at 5W in your product. By doing so, you’re building redundancy into your product where you know that the resistor can cope with the Wattage being put through it and it is less likely to fail, rather than being on the limit or being understrength. (20:26)


Recap: The best engineering practices for reliability.

Make sure that you have a good design, select appropriate components, analyze data after testing, implement solid manufacturing processes, check cartons before shipping to make sure that products won’t be damaged during transit, and make sure that user manuals are tested to check that they provide the ideal results for users. Doing this should ensure that you have a reliable product. (23:08)


The design for reliability process we follow to reduce our clients’ reliability risks.

A client may come to us with a product design, for example, and we follow the DfX and Design for Reliability process.

  • We will evaluate the design and consider industry standards and the design guidelines in case changes must be made and consider DfR in relation to them in order to have a design that can be manufactured well with low reliability risks.
  • We audit component and material suppliers to make sure that they’re capable of providing components that will handle the product’s stresses and remain reliable.
  • We build prototypes that simulate the realistic and worst-case use cases of the final product by the customer (i.e. if it’s a consumer product we won’t test it like an airplane would be tested) so issues can be found and fixed during the product development phases so reliability issues don’t make it to the field.
  • During testing, we do a Pareto analysis of failures, failure analyses if needed, and create and implement a corrective action plan for the failures, and a subsequent round of testing to assess whether the CAP has been effective and the failures are fixed.
  • Manufacturing processes are assessed and automation, mistake-proofing, jigs, and assembly fixtures will be implemented where needed to reduce reliability and quality issues caused by manufacturing errors.
  • We always recommend that shipping cartons are run through ISTA-2a testing to assure that the products will be protected from damage.
  • Finally, we test and provide feedback on the user manual. (24:32)


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