ESD Grounding
ESD Grounding
(OP)
I have an issue that is eluding me regarding ESD grounding of carts. We have metal carts in our facility that we use for material movement between work stations (and some workers use for storage). In our previous building we had a regular linoleum tile floor which had ESD wax applied once a quarter. Because the wheels of the metal carts are not ESD grounded I used a drag chain attached to the bottom of every cart which has worked well for years. Testing with our ESD tester by putting one 5 lb electrode on the shelf of the cart and one on the floor. The carts measured in the dissipative range. Fast forward to the present. We bought a new building and spent a ton of money putting in static dissipative flooring in the production area. We grounded all our workstation ESD mats and everything passes when measured from the mat to the floor. However, I cannot get my carts to pass. I verify the top shelf is electrically connected to the bottom shelf and both are connected to the drag chain but I get an insulative reading on my meter when testing from the cart to the floor.
Additionally, using my static meter I see no indication of a static charge built up on the carts. Why am I not getting any continuity to the floor through the drag chain (I have even tried a much larger and heavier chain than the jack chain used in the old building)? Am I wasting my time trying to ground a metal cart that doesn't show any static charge? Curiously, I use my static meter on a PET disposable water bottle which are strictly banned from the production floor and see no static charge but the company provided and sanctioned covered mugs generate a ton of static. I talked with the flooring manufacturer and didn't get anywhere.
Any insight would be appreciated.
Regards
Additionally, using my static meter I see no indication of a static charge built up on the carts. Why am I not getting any continuity to the floor through the drag chain (I have even tried a much larger and heavier chain than the jack chain used in the old building)? Am I wasting my time trying to ground a metal cart that doesn't show any static charge? Curiously, I use my static meter on a PET disposable water bottle which are strictly banned from the production floor and see no static charge but the company provided and sanctioned covered mugs generate a ton of static. I talked with the flooring manufacturer and didn't get anywhere.
Any insight would be appreciated.
Regards





RE: ESD Grounding
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: ESD Grounding
TTFN (ta ta for now)
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RE: ESD Grounding
I am trying to prevent ESD damage to parts and or boards being transported within the same ESD safe area. We do use ESD trays to move PCAs on the carts as well as ESD totes to carry other parts. I was trying to tie the carts to the dissipative floor so as not no generate any additional charges.
RE: ESD Grounding
according to https://www.staticworx.com/articles/esd_flooring_t... and http://www.gotopac.com/art-esd-resistivity a static dissipative flooring has between 1 megohm to 1 gigohm of resistance to ground. That said, there may be some voltage dependency that your meter is unable to overcome.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: ESD Grounding
RE: ESD Grounding
Put a 6x6" metal plate on the floor and hook it to the bottom of your cart with an alligator jumper and see what happens. Step slowly on the plate and see what happens. It may be the floor not doing it's job at all. Perhaps it's over concrete that is somehow not grounded at all.
Keith Cress
kcress - http://www.flaminsystems.com
RE: ESD Grounding
Comokid. The cleaning crew isn't waxing the floor. It is cleaned per the floor manufacturers specification and tested using the Desco meter described above. The floor tests well within the dissipative scale at various point throughout the production area. It is the drag chain not contacting the ESD floor as well as it contacted the ESD waxed floor
itsmoked. If I touch the cart and performm the test the cart measures good. If I step on the 6 x 6 metal plate I am doing the same thing. I'm considerably heavier than the 5 lb electrode from the tester and I also wear ESD shoes at work.
RE: ESD Grounding
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: ESD Grounding
I thought of the chain cleanliness so I cleaned it to no avail Then I tried a brand new much heavier chain in an attempt to get better contact with the floor. I think I'm going to have to face the fact that I cannot ground (yes, I mean in a static dissipative sense) like I did in the old building and we will have to employ other ESD safeguards like bags and totes on the cart.
RE: ESD Grounding
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: ESD Grounding
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.