Quality and Reliability Relationship
Kirk and Fred discussing the relationship between quality and reliability. Quality can lead to a functional failure but sometimes is cosmetic or feel of a product.
Join Kirk and Fred as they discuss further the ways that reliability can be affected by poor quality and lead to different ways that lead to customer dissatisfaction.
- Quality problems such as cosmetic issues such as paint flaking off can lead to returns as “failures” even though the products are functional.
- Customers may see quality issues that are not functional failures as indicators of poor probability of future reliability
- Reliability is a subset of overall quality with some overlap, but typically the most serious and important factor to the customer
Enjoy an episode of Speaking of Reliability. Where you can join friends as they discuss reliability topics. Join us as we discuss topics ranging from design for reliability techniques, to field data analysis approaches.
For more information on the newest discovery testing methodology here is a link to the book “Next Generation HALT and HASS: Robust design of Electronics and Systems” written by Kirk Gray and John Paschkewitz.
Jay Uppal says
Hi Fred and Kirk,
Got this thought stuck in my head after listening to the episode and would love to see what you guys think about it. It’s probably just the Reliability Engineer in me speaking but I’m definitely going to put the point across.
I’m talking about the phone case protective cover example. If the packaging says the case is supposed to fit the phone you’ve purchased, and it doesn’t – is it a Quality or Reliability failure?
Without any other information, I need to make an assumption about a follow up question that arises – what was the design requirement?
The requirement had correct dimensions. This makes it a quality failure because the product was not manufactured according to specifications. (Fred, I understand the way you look at it and say the the product has been returned and somebody has to pay for it, so it is a reliability issue.)
The requirement had incorrect dimensions. This also makes it a quality failure because the specifications were not double checked before passing design reviews and moving on to production.
The verification-validation analogy comes to mind when I think of reliability-quality. If the product fails after “verifying” that it was manufactured, used, and maintained correctly, then it would be reliability failure. If the product fails because of incorrect “validation” in designing, manufacturing, or use, then it is a quality failure.
Thoughts? Comments? I’d love to get a second opinion.
Fred Schenkelberg says
Thanks for the comment and for listening, as well.
Hand not thought of the separation as you lined it up and it makes sense to me. Yet, it’s still a problem faced by a customer and the organization’s response will likely not change whatever the problem is labeled.
I do agree with Kirk that sometimes the initial review of the problem classifies the issue to a likely group to resolve the issue, yet to me that is just sorting/guessing to get to a resolution quicker.
Kirk and I will have to open this discussion up again and explore your two cases a bit more.
Jay Uppal says
Sure, I agree when you say the problem still persists and the organization as a whole still has to find a solution, no question there.
My comment was only to get feedback on the thought process of distinguishing between quality and reliability from a bird’s eye view.
Kirk Gray says
Thanks for listening to SOR and for your comment.
In case 1 you have a “manufacturing quality” issue that has possibly a large variation in dimensions that leads to a percentage of customer returns, but I would not call it a reliability failure as the phone is still completely functional and the defect is not latent, its patent.
Case 2 is more of a “design quality” verification issue that leads to customer returns.
In both cases there is a customer return, so it is the same cost to the supplier as a reliability failure, but I would not consider them failures of reliability which I see as a failure after time zero of acceptable function and use.
I don’t know if that helps, but the two cases you make, overlooked manufacturing variation and design margins are major causes of latent defects, more of what I would define as reliability issues.
Thanks again for your comments
Jay Uppal says
I think you’ve summed it up beautifully. I like how ‘manufacturing quality’, ‘design quality’, and ‘latent defects’ conveys the message.
Thanks again for sharing.