@elk and @Paul. Yes, production can be improved by simple measures.
For the enclosure assembly line you can make fit to purpose nylon molds, put the parts in, such that they can not go anywhere during assembly, tighten the screws with a torque driver, take the enclosure out of the mold and there you go. It is that simple!
One might think it makes the workers life more simple and even increase production speed.
Nylon won’t scratch the aluminum a bit. When those molds have proper “guide in” sections, they last for many enclosures to make.
It will improve tolerances and quality consistency.
One condition is that temperature and humidity should be controlled to a constant level. Which I assume is the case at PS Audio.
I suggested, years ago, they use jigs for assembling the chassis to solve the out of square problem. Yet the problem still exists. But it shouldn’t need that. They just need somebody during the process to be more vigilant. Such things can’t escape at least three sets of eyes unnoticed, but they do.
I also suggested they use locktite on the screw threads so they don’t come loose. They said they would. But the screws are still coming loose. I suspect they weren’t done up tightly in the first place when only two come loose in a chassis of 16.
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Anything made assembled with appropriate tools, help pieces like jigs / molds you only need one pair of eyes, it’s the pair of eyes that are expensive and as being human, perhaps not catching everything. Maybe a lack of quality tolerances / standards. If there is no standard for those corners or squareness of enclosure, why would a worker in the factory bother reporting. There is no rule to put it in the dedicated non conforming goods area to have it reworked or scrapped.
But there should be quality tolerances and a standard for things like those chassis gaps, and it should be written down on a production assembly instruction, and it should be assembled exactly in accordance with the instruction, and checked off by a 2nd person on a unit production record that the required items have been performed. When the screws have been tightened to the correct torque, apply a witness stripe. It’s easy to do and just takes a few seconds. The guy doing the final assembly check just needs to sight the witness mark on each of the screws, and then sign off that box on the checklist on the unit production record. You can’t have the same guy doing all of the above, a 2nd person must be involved to help prevent the holes in the Swiss cheese from lining up. This is not rocket science!
The 2nd pair of eyes doesn’t become expensive in comparison to customers being less accepting of these things, and instead of trying to fix them themselves, send them back to the dealer/factory for rectification.
Lucky that PS Audio don’t build heart pace makers or nuclear power stations, etc.
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I absolutely agree, the second pair of eyes can be the worker performing the next process step.
None of those misfit enclosures should make it into the painting process. As they can not be reworked after the paint has been applied. The further those misfits make it into the manufacturing process the more expensive to scrap, so nobody dares to call the shot. “Maybe the customer won’t notice or care” which seems to work too ;-).
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Perhaps the enclosures have too many parts and screws to begin with, maybe the material is less expensive, but somebody needs to be paid to put those screws in and preferably with the parts in perfect, shape and fit. Then torqued correctly, maybe even applying Locatie on every of those 16 little screws to make it last. Without jigs and tools that is quite the challenge.
Somebody in China/Taiwan used to be paid 900 RMB/month to do it, and they did a reasonable job of it. Now somebody in Boulder does it, at a much much higher salary.
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I bet shipping from China / Taiwan to Boulder is for free, especially the re-work units. Regardless who puts it together, it’s QA management, verification/testing, tools and their QA targets that determine if the misfits make it to electronics assembly and ultimately the one or other unfortunate customers.
More than one unfortunate customer, there have been a few reports here of chassis gap misalignment and loose or missing screws. Screws just don’t get loose if tightened properly in the first place. No matter how rigorous their shipping experience.
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Agree, hence my suggestion to use a torque controlled screw driver. Of course that needs to be maintained, handled and regularly calibrated, we have a little unit at our work that allows daily calibration within 1 or 2 minutes. That daily calibration unit is then annually sent out for third party calibration in accordance with ISO 17025 QA standard for calibration labs.