The industrial automation project I just finished is a showcase for a certain manufacturer. I used its PLC, HMIs, VFDs, Ethernet-networked IO, sensors, and safety products. It was a one-stop shopping trip. In only two instances did I have to go to a different manufacturer for a particular component; the showcase manufacturer simply did not make those components. I’m very proud of the way the system came together almost exactly as we initially designed it. We did run into some surprising Sherlock Ohms-type cases though.
The one I wish to discuss involved its safety system. E-Stop buttons, light curtains, and guard switches feed into a bank of modular safety relays to create several safety zones. E-stop buttons and guard doors will interrupt the entire system, but breaking the light curtain on the right side will not interrupt production on the left (and vice versa). The modular safety relays use input modules, a base module, and output modules (sort-of a mini-PLC in approach).
The odd behavior involved resetting a time-delay output module. Sometimes, that module would not reset, even though the base module had passed the reset signal to it and reported all output modules energized. The symptoms were difficult to trace; the system had no safety events active, the safety circuit reported all was well, but no motion. Several times, I found myself digging through the program looking for a chunk of logic that wasn’t working the way I expected.
On the one hand, it was a relief to discover the logic I’d created was fine, that it was a hardware component that would sometimes not reset when told. On the other, there was no reason for this to happen, and the sporadic nature was not helping. Eventually, our supplier was able to produce a tech notice published by the manufacturer describing exactly the symptoms we encountered.
Unfortunately, there was no easy fix for the component. The manufacturer said it was a defect in the firmware, but that the time and cost involved with fixing the firmware of a safety product weren’t justified when they were in fact planning to roll out the successor to that safety product line.
I would think the economics of this are very clear. Sending bad products out the door will cost more in the long run than fixes would cost. Given that, this story is probably one of line managers rather than executives. This decisions was probably made to meet a quota, and those directly involved were probably hoping those at the top wouldn't notice anything except that the quota was met.
In today's world of tweets and Facebook chatter, companies--be they consumer focused or industrial--can really pay the price for letting faulty products out the door. Rob is right--there's a huge price to pay for that, both financially and in taking a hit on your brand reputation. But I have to agree with the others that the bigger lesson for engineering is getting the product right the first time.
"Either a notification when the order is placed (a red flag in the manufacturer's order entry system to let the buyer know), or how about a warning label on the box, or an insert with the installation instructions?"
In semiconductor products (ICs, memory, ASICs, etc.), the customary practice is to indicate on the product's data sheet (online web page), and on all summary and selector guides, the phrase "Not recommended for new designs." That tells it all, without having to indicate that a part doesn't behave as expected. The savvy engineer either avoids the part or inquires about the fault.
Insert that phrase into your favorite search engine to see how widely it is used.
It's amazing that they let it get this far. Knowing that this is the attitude of that particular company, I wonder if the engineers will continue to specificy its products in the future. And if word starts getting out about that company's name....
Rob, I think you're right. There have been tons of studies done that demonstrate and verify this simple principle: people complain to each other about lousy products and bad service. Even more important, trying to reverse the effects of bad press, deserved or not, is not only nearly impossible but can backfire. It's mind-boggling that these messages don't seem to have been driven home for some companies.
On a purely economic view, I can't imagine the practice of letting faulty products out the door can do anything by hurt the company's bottom line. There's the potential of costs in returns and repair, but the biggest cost may be in goodwill. As you can see from Made by Monkeys postings as well as the discussion boards, a customer who gets a bad product will talk to a lot of customers and potential customers. That's gotta cost.
Certification and re-certification are issues for both safety products and military products. Getting things certified for use by the military is also a gigantic pain and re-certification even more so, and all of it, of course, costly. Yet suppliers to the military know this, and if that's what it takes, that's what they do. Why should consumers have it so much worse than soldiers, and be subjected to manufacturers who can't be bothered with a certification process?
I will gladly pay somewhat more for better quality. But I find it increasingly difficult to find those better quality products.
This article demonstrates the importance of getting it right the first time. TJ is absolutely right that the company's handling of this issue was inadequate. But if the company hadn't let a defective product out the door in the first place, they wouldn't even be in the awkward situation of having to respond to a problem like this. Nobody's perfect, but attention to detail upfront can prevent a lot of heartbreak down the road.
This story brings out a point that most folks are not aware of, which is the paperwork and testing that are needed for a product to be a "certified safety product". It was undoubtedly the paperwork and recertification required with any change that made them refuse to correct the problem.
Now we see ads describing how wonderful it will be when the safety system is a integral part of the control system. BUT, consider what happens if the system gets into the field and a problem anywhere is discovered. Fixes would be less likely because any change woulr require a re-certification, which costs money. Keeping the safety system separate may be less convenient, but it is the best way to avoid that sort of problems.
TJ, thanks for writing this article. As a consumer, I can't count the number of junky products I've bought unknowingly--way more in recent years it seems--with no recourse because their defects didn't cause safety or health problems. In many cases, thought, it was a similar situation. Your key phrase, I think, is "Why then, did the manufacturer continue to sell (and still sell) a product with a known defect?" And also, the fact that there was no warning. Of course, a warning would dissuade a lot of people from buying it. Your other key phrase is "But how many engineers have the time to search technical support Websites for potential defects of all the components in a design before you place the order?" Exactly. That's what quality practices were supposed to be about.
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