|jeeze Reddit it’s after twelve PST, don’t you have to get up early tomorrow? [Hafa adai other time zones]
David Swenson of 3M Corporation describes an anomaly where workers encountered a strange “invisible wall” in the area under a fast-moving sheet of electrically charged polypropelene film in a factory. This “invisible wall” was strong enough to prevent humans from passing through. A person near this “wall” was unable to turn, and so had to walk backwards to retreat from it.
This occurred in late summer in South Carolina, August 1980, in extremely high humidity. Polypropelene (PP) film on 50K ft. rolls 20ft wide was being slit and transferred to multiple smaller spools. The film was taken off the main roll at high speed, flowed upwards 20ft to overhead rollers, passed horizontally 20ft and then downwards to the slitting device, where it was spooled onto shorter rolls. The whole operation formed a cubical shaped tent, with two walls and a ceiling approximately 20ft square. The spools ran at 1000ft/min, or about 10MPH. The PP film had been manufactured with dissimilar surface structure on opposing faces. Contact electrification can occur even in similar materials if the surface textures or micro-structures are significantly different. The generation of a large imbalance of electrical surface-charge during unspooling was therefore not unexpected, and is a common problem in this industry. “Static cling” in the megavolt range!
On entering the factory floor and far from the equipment, Mr. Swenson’s 200KV/ft handheld electrometer was found to slam to full scale. When he attempted to walk through the corridor formed by the moving film, he was stopped about half way through by an “invisible wall.” He could lean all his weight forward but was unable to pass. He observed a fly get pulled into the charged, moving plastic, and speculates that the e-fields might have been strong enough to suck in birds!
The production manager did not believe Mr. Swenson’s report of the strange phenomena. When they both returned to the factory floor, they found that the “wall” was no longer there. But the production workers had noticed the effect as occurring early in the morning when humidity was lower, so they agreed to try again another day. The second attempt was successful, and early in the morning the field underneath the “tent” was strong enough to raise even the short, curly hair of the production manager. The “invisible wall” effect had returned. He commented that he “didn’t know whether to fix it or sell tickets.”
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Have a relative (sort of) who works at a 3M plant. Shit still occasionally happens.
> You can’t just say that and go away!! How are you not irresistibly
> interested in that?? I would’ve interrogated that relative so hard
It just came up in passing at Thanksgiving! I don’t really know him that well; he’s an in-law. He mentioned being able to throw small washers and bolts at the field and watching them get repelled. People got interested, and so someone came with a voltmeter, and after throwing a couple more, they checked for voltage, and there was a residual charge after they finally caught on on a plastic sheet to prevent immediate grounding. It also had a very slight magnetic field. It’s apparently fairly common, but engineering hasn’t come up with a solid explanation why.
ALSO: dc469 5/2016
|The ‘force field’ event was from 1980, while the report was given at an ESD conference in 1995. Where is that machine today? In other words…
Does that 3M sheet-slitter still slits sheets? Single sheet slitted into three slit sheets spooled onto spools called ‘jumbos.’ The supposed sheet-slitter shift staff says 3M sold that sheet-slitter. It may be surplused and still exist, sitting in SC, slitting and spooling someone else’s slit sheets. Or, since OSHA’s lawshuits when staff suddenly statically sucked into sheet slitters don’t exhisht shouth of the border, it may haved moved to Mehicco.
From: Beaty, William J
Also: I wonder if the (I assume) huge quantity of air ions had anything to do with your weird phenomenon. Maybe the “wall” effect involves a plug of ionized air which is held in place by the opposite charge on the film. If so, your repulsion phenomenon would not occur if the “tent” of film was replaced with highly charged metal plates, since the source of oppositely-polarized electric wind would then be missing. I’m still convinced that the charged film should produce an attractive force upon a human body. Repulsion requires that the human be charged with the same polarity as the PP film, yet induction should produce an *opposite* body charge, so attraction is expected. But if a plug of oppositely-charged air was strongly attracted into the “tent” of PP film, it might produce a significant pressure-gradient in the surrounding air. A fraction of a PSI per foot would be more than enough to prevent someone from walking forward. If this is the origin of the effect, then the repulsion forces you experienced involved air pressure rather than electrostatic attraction/repulsion.
This might be an entirely new way to accomplish levitation. Attract a whirling blob of ionized air to an oppositely-charged plate, then use the resulting pressure gradient to lift and manipulate uncharged objects. Sort of like a fluidized bed, but using charged air instead of sand.
Why doesn’t the population of opposite ions “plate” itself onto the plastic surface? Maybe it tries to do so, but the air within the moving tent is swirling like a horizontal tornado, so the charged air cannot simply move straight to the plastic film. If true, then the phenomena would not appear if motionless charged air and oppositely charged plastic were present. The tent shape and the motion of the plastic would also be required. Incredible coincidence that all the required components could ever come together in one place! (if this is indeed how it works!)
Speculative, untried experiments: MOVED TO http://amasci.com/freenrg/iontest.html