I have a dual coil running in a helios and the coils have seen about 2 weeks of use right now. I just sat on my mod and it fired for about a minute and a half straight, ate through the cotton, needed to be rewicked, some new orings, but the insulator looks fine. Now it seems my coils heat up more quickly, and glow more brightly than they used to. Does the resistance lower over time with kanthal? or am I just imagining this. thanks in advance
What happens to kanthal over time and intense heat production?
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Ok I am guessing you didn't torch your wire before you wound the coil? But I find the metal does set in and will change resistance.
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You can google the science but basically the wire is made by pulling thick rods through smaller and smaller holes to reach the desired diameter. This process puts stress in a length and compression format. Torching allows the metal to release that tension which improves conductivity.
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i didn't torch these coils after wrapping them, so this was a long minute and a half (my best guess) burn and they seem to heat up more quickly and more intensely now.
I usually burn my coils with a torch while I hold them tight in a tweezers, but not always sometimes I use my mod to heat them. Resistance over time will increase in wires.
Most times after constant heat expansion and cooling contraction of metals the metal generally fails and breaks to becoming brittle, and resistance generally increases in kanthal from this. As long as your insulators are good, I have run coils made out of 26ga or thicker for up to 3 months with the occasional weekly rewicking, dry firing off carbon on the wire before the rewick and after removing the old wick, 28ga to 32ga I've gotten close to 2 months. Basically I run mine until the coil pops and fails due too physics of the first sentence. So you should be fine, just dry fire the coils and rinse them before rewicking the coils.
After repeated heat/cool cycles coils/attys resistance goes up so the coils make less heat. Some people think it's because the joints corrode. Some people think it's because the wire changes. I don't know why it happens, but I know it does. I've seen it in my attys.
Your coils or atty setup have changed. IMO if you like the change all is well
Resistance can only increase in a wire with extreme use. when I squeeze my wire coil in tweezers yes the resistance would go down, but only while its being compressed by the tweezers. This is the effect of shorting the wraps that make up the coil. When you let the coil go the wraps that were touching generally separate just enough to remove the short and resistance would increase. once installed on the Atomizer and heated the wraps that make up the coil will actually separate a hair more this happens because the wire as it heats expands. this is also the reason why your coil will read .5 ohms when first installed and after burning in and tweeking may read .6 .7
Hope this explains it a little better
Great explanation of the coil expansion. The coil becoming brittle is a function of carbonizing the metal. The small amounts of carbon get deposited while the metal is hot and expanded and then the metal cools "grabbing" a few carbon molecules, changing the metals surface. Eventually the carbon content gets high enough that the metal is expanding faster in a less carbonized area and a break occurs.
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It may seem to be lighting better now cause you burned off the build up of gunk on the coil. I dry burn before every re-wick, hits like a new coil again
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Kanthal wears out. When heated, Kanthal wire (iron-chromium-aluminum) builds up an aluminum oxide thermally conductive coating on it's outside surface that protects the individual coils from shorting, one to another. This is called alumina (Al2O3).
Once the aluminum content diminishes to the point where that oxidation resistant, electrically resistive alumina layer isn't produced... all that remains is iron and chromium oxide.
Exposure & contamination degradation, inconsistent heating, increased resistance and ultimate wire failure aren't far behind. Chances are, you'll see the blackened, pitted wire or perhaps even taste the iron, long before that failure occurs.
Exactly rite. I always used scaling as an example, but your explanation is more on the science of it all. Mine just the dumbed down version lol.
Hahaha mine is no where near the level of SoF. He hit it on the head for sure.
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Thank you Tom. I've also written a brief article on the subject of why Kanthal doesn't short out... should anyone have an interest.
I have made it a point to try not to explain how kanthal coils can all touch and not short. Your article does it justice. Most of the immediate fluctuation in resistance when firing is due to the tension in the metal. Torching before wrapping, then squeeze and torch again sets the metal and eliminates the "set in" period I read people talking about.
The article SoF posted illustrates why kanthal is used over say copper.
I am curious and admittedly just now, as to how much of that aluminum ends up in us? New vape research for this guy.
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The article SoF posted illustrates why kanthal is used over say copper.
I am curious and admittedly just now, as to how much of that aluminum ends up in us? New vape research for this guy.
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For those that don't know.
Kanthal is made by taking larger rods of aluminum and a few other metals and pulling them through holes mashing them together to a fairly consistent level. However when you torch it to glowing red the individual metals blend fully and release stress energy.
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Kanthal is made by taking larger rods of aluminum and a few other metals and pulling them through holes mashing them together to a fairly consistent level. However when you torch it to glowing red the individual metals blend fully and release stress energy.
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