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> I know an engineer who spent two years of his life making sure the new water pump designs would fail at warranty + 50 percent, but only in an annoying, non ca

• albrewer 2y ago
  In mechanical design, you typically target an order of magnitude of stress cycling for product design. In a pump, everything stress cycles, so it all needs to be simulated. If this was a pump you were going to make ten million of, then suddenly every fractional 10th of a cent you save becomes the difference between, e.g., having another coworker or not. So to balance that with offering a reasonable warranty such that there's actually demand for this product makes sense. Before anyone brings it up: sure, a lot of companies just pocket this savings or whatever, but a lot don't; you just don't hear about them because they're typically midsize companies that nobody complains about.
  • mort96 2y ago
    I'm sorry, but I feel like you're reading my message extremely uncharitably. I'm obviously onboard with the idea that nothing lasts forever, and time spent figuring out how to increase something's lifespan to "at least X years" is obviously valuable, as is time spent figuring out how to cut costs without making a product break "before X years". But none of that is the same as spending time to figure out how to ensure that something breaks at the right time. It matters whether the focus is on reducing costs while keeping track of the impact on the product's lifetime, or the focus is on reducing the product's lifetime. What I'm calling a waste of talent and human life is spending time on the latter, and that's what it sounds like my parent comment describes their engineer friend doing.
    • eschaton 2y ago
      Amen, intent matters. And it sounds like in both of the cases the OP cited, the intent was to force otherwise-unnecessary replacement, which is bad.
    • albrewer 2y ago
      > none of that is the same as spending time to figure out how to ensure that something breaks at the right time Yes it is. At the absolute limit, balancing cost and reliability is this exact optimization exercise; we are talking about the exact same thing taken to different extremes. The difference between your ideal scenario and the practice outlined in the OP is the difference between 97% BOM efficiency and 99.99% BOM efficiency. At extreme scales, that gap can mean the difference between a company laying people off vs. surviving. Side note - this same discipline is what ensures your widgets fail in a safe, controlled manner and not in a catastrophic way. > I feel like you're reading my message extremely uncharitably I saw an naive take on how mechanical design for failure works in practice and wanted to educate. I mean no disrespect, it's just seemed like it might be an unknown unknown for you. Your comment had at least a few upvotes, so there are others out there who may also lack the same information. To your charitability point, though, my first take on the OP above is probably the most charitable take. The least charitable scenario for the OP is that the company wants to make sure they have higher annually recurring revenue from replacing their widgets breaking down but need to _barely_ beat or match the other guys in a warranty. Reality is probably somewhere in between.
      • deleted 2y ago
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• mkipper 2y ago
  This can be a pretty blurry line. If the engineer took some existing product and did nothing for 2 years other than design in additional failures that show up after the warranty has expired, I agree that's awful. However, I'm very skeptical of that. I've worked in some manufacturing orgs who try to pinch every possible penny they can, and I've never seen anything resembling that level of mustache-twirling villainy in engineering. Also, 2 years seems like an incredibly long time for someone to spend doing this and nothing else. It's much more likely that the company asked the engineer to reduce the cost of the pump while still hitting the product's requirements (e.g. no failures during warranty period plus some margin), and while doing that, the engineer found the design was overspeced for those requirements and made some changes which reduced the pump's expected lifespan while still meeting that requirement. Unlike what the OP is suggesting, this happens constantly...it's what engineering is. Obviously I'm not OP and I'm reading between the lines here, but it's very easy to imagine someone hearing this story second-hand and completely misrepresenting it.
  • K0balt 2y ago
    I think it’s something in between. The new pump actually cost more to make than the old one it replaced. The old pump would 90 percent make it through warranty, but sometimes failed early. If the old pump failed, it often did so in a way that caused additional warranty expenses and reduced reliability perception. The problem was that a seal failure could cause catastrophic bearing failure. So, the new pump was designed so that a seal failure would not cause bearing damage. Good sealed Bearings properly specced are very reliable these days, and seals on a true shaft wear very little. The problem was that the new pump would invariably make it to EOL. So after spending a few weeks designing a no-fail pump, they had him redesign it so there was criticality in one of the bearings, so that one was effectively overloaded and would develop enough play to cause seal wear, (and dripping) while the other bearings would prevent the shaft from actually failing. The thing is, it’s hard to spec a bearing for “will wear a little out of tolerance but won’t fail” so it took two years and a lot of testing to get it right. In all, there was a considerable amount of moustache twirling going on. But not as much as in those damnable disintegrating plastics or the unneeded battery in the thermostat.
• whaleofatw2022 2y ago
  Oh i think I saw an AvE video where they explained a cheap part being omitted resulted in this exact sort of problem.