I'm looking for a tape that is very thin. Thinner the better as I am actually looking to have it wear out through mechanical abrasion. Any suggestions?
Ok, was thinking along the lines of an adhesive backed tape. Only reason I want thin is so that I can slowly abrade through it, eventually abrading all the way through it.
Might not have to be tape, could be paint on coating?
I know it's a little vague, but abrading through the tape/coating is inention here. It needs to protect the surface it's applied to until you abrade though the tape/coating, at which point it exposes the surface.
Fair enough Compositepro. I'm adhering it to a shaft, so needs to be flexible to wrap around that. Most likely steel shaft, but may be other metals at times so it needs to stick/adhere to that. I started this out with thin because I don't have a lot of normal force being applied to abrade the surface away.
To give you a feel here on how setup abrades steel (time and depth) currently it takes about 6 months abrading steel shaft before I see issues I am trying to mitigate and it only abrades it less than .0001 or less per SEM imaging.
So either need something thin or soft or both.
Not trying to be vague here, just trying to expand on a thought to solve my issue.
Well, here in my AFM world Kapton Tape seems to be the go to for, well most things, so given the lack of background/context you're still giving I'll throw that idea out there.
Watch out for the adhesive on any tapes. With abrasion you might end up with a gummy mess you hadn’t counted on. In fact the heat caused by rotation of the shaft could soften many tapes, and make a mess. I’d vote for a thin coat of spray paint, and there are many variations in terms of hardness, abrasion resistance, etc. You could use spray metalizing (flame spraying), and with the right material application this is a wearing surface. I can’t figure out what you are really trying to accomplish. Why not remove the protective coating just before final assembly, and be done with the potential mess.
Well, thanks for all the responses even though I know I'm being pretty vague. I'll try to give a better description here of what I'm battling:
As shaft surface abrades it rusts, so loses electrical conductivity which is necessary for product to function. Cleaning shaft periodically solves problem, but item isn't located in accessible area for maintenance. Can't change shaft material or coat shaft with say electroless nickel or some other coating as shaft isn't our component piece. Can't change material abrading surface -- this is our component, and tried that but effects other functionality of product. Have yet to discover any electrically conductive through coatings/tapes/paints, etc. that can be applied in the field to resolve shaft rusting issue as most times our product is a field retrofit that will still allow product to function.
Any suggestions on conductive through tapes/paints/coatings easily applied in the field would solve my problem.
Sacrificial abrasion surface thought is to be able to periodically expose area of fresh shaft surface periodically.
I've thought about the adhesive making a gummy mess which makes me lean towards spray paint/nail polish choices. I'm actually going to rig up a test using nail polish. Issue I see with spray paint/nail polish type choices though is how thick the customer applies it in the field which effects how fast wear through layer. This makes me lean towards adhesive tapes as then I know how thick my sacrifical wear coating is.
Hadn't thought about the heat on the shaft loosening the adhesive on the tape.
Removing protective coating right before final assembly is a no go as the issue I'm trying to mitigate happens during use of the product.
Does this help get rid of the vague-ness? I'd love to solve it another way and open to suggestions on how to do that, but right now accessibility and what items I have ability to change and control are driving a lot of the decisions.
If you need electrical conductivity, the paint/nail polish may not work. Most make decent insulators. Back when I was in school, I used different nail polishes to insulate solder connections on wires when building a transformer. Even the stuff with the metallic sparkles was insulating. That being said, there are conductive paints out there. You would want to test the various types for adhesion and conductivity, as well as make sure you dont set up for galvanic corrosion.
Mysterrose, what, on the shaft, is your component abrading thru, to start the rusting process? What is causing the rust, moisture in the air, or another source?
Despite the explanation, there is still significant mystery here. I would assume that the minor wear (why abrasion to any extent?) would keep the shaft polished and prevent corrosion. What’s so abrasive about your part, can’t you modify that in some way so that is polishes and inhibits rust? Why not clamp some sort of conductive collar to the shaft, which can be sealed at the edges, can wear significantly over a longer time period, and then be changed out for a new collar.
KllrWolf: We've tried conductive paints and have found a colloidal silver paint that seems to work ok. That in itself only prolongs issue until we see the rusting. Perhaps it's not an ideal solution because we are seeing Galvanic corrosion between the carbon steel shaft and silver particles? Sacrificial wear layer to me needs to do more to protect shaft from rusting until it is worn through than be conductive as I don't necessarily have to paint whole shaft. I could say paint only half the shaft, so that at beginning the unpainted half provide conductivity. Then as unpainted section becomes conductive, hopefully I've worn through the protecting sacrifical layer on the other half and now have a "like new" section of shaft that is now conductive.
SnTMan: It's just abrading a plain Carbon steel shaft. My guess is that as it abrades the surface it exposes fresh Iron which then rusts by reacting with the air giving you an iron oxide Fe2O2, Fe2O3, etc.. Moisture in air is probably only source of any water present, but I have no control over customers environment and be tough sell to try to convince them to control the environment.
dhengr: Can't modify portion of our part that rides on shaft due to how it works and proprietary processing methods already developed around it that require use of the specific material (I apologize for being vague on what material abrading shaft is, that part is proprietary to company, but lets just say it's really really hard).
I don't think we get any real polishing taking place due to very low normal force between our part and shaft. As mentioned earlier wear over 6 months is less than .0001 inches. I have a suspicion that the "micro-abrasion" may be doing something to surface level grain structure in some way. We've discussed collars, but that then becomes a maintenance item. Also opens us up to any galvanic corrosion between collar and shaft as most likely would want collar to be either hard chrome coated or stainless due to the wearing issue.
How about a picture and better description of what problem to solve? What is it about conventional methods of conducting electricity to a rotating shaft that is not possible? Why doesn't a slip ring work? Why don't brushes work?
