What's new
What's new

What material is this brown o-ring?

Mud

Diamond
Joined
May 20, 2002
Location
South Central PA
I want to make O rings to replace this one on a gearcase. It's square cross section, measures .100 th. The color is brown which I'm not familiar with and don't readily find in cord stock. I've seen silicone is listed as red and it looks close to this color, but silicone is hard to bond together. There's nothing about this that would demand an exotic material, but I'd like it to look OEM for customer approval. Anyone here familiar with this?

20191121_130645-800.jpg

20191121_130446-800.jpg
 
Brown is most commonly FKM (Viton). If you measure .100" the standard cord stock size is almost certainly .103"

Is the application an automatic transmission? Viton holds up to ATF better than the more common NBR/Buna-N/Nitrile which is used in most oil-based applications.
 
Thanks guys, that was fast! I see Viton listed as black most places, are there different colors of Viton or is this considered black?
I do agree it's .103 or 3/32 (or maybe 2.5mm)
No, not ATF, just oil like engine oil. Does Viton glue OK with cyanoacrylate? The cord is about 55" long or 17.5" dia, To get them made is $25 each in 250 quantity so I'm stuck with making them 5 or 10X per year
 
There's different colors of Viton. Brown, blue, black, green are the colors I know of. I'm sure there are more.

As far as bonding with cyanoacrylate, it will bond fine.
 
I have never seen black Viton rings, they've always been green or brown for me. The big difference is that they are stiffer, and have better chemical resistant because they are a fluorine base material. I believe we had a special adhesive just for Viton, but I seem to remember seeing people just use the cynoacrylate glue as well. I think a vulcanizing kit is recommend.
 
Viton I usually associate with black and brown about equally, but it's the only thing I know of that is brown.

HNBR (Hydrogenated Nitrile) is what I think of when you say green. It also comes in red, like a burgundy/maroon color. And black.

Silicone is also commonly red, but it's more like a rusty orange red. It's also the easiest to get in a wide range of colors.

EPDM is sometimes blue or purple, though I've almost never seen the purple stuff, as black is by far the most common.

For NBR, Henry Ford would be proud: you can have any color you want as long as it is black.

Edit to add: for your application, I would imagine that a simple cyanoacrilate bond is enough if you're careful with it on installation. Don't forget to lubricate the ring with the process fluid! I'm guessing that since this is a gearcase that you're dealing with a static seal, partial fill and vented to atmospheric pressure, so if you're worried about it, orient the splice to the top where it isn't relied on, and start the install opposite the splice. That way, you aren't ever putting tension on it.
 
I've seen black and brown buna and viton, we only use viton which is more chemical and heat resistance . Viton is usually has a flat surface finish , buna is usually shiney , they come in different durameter's of hardness , 70 usually the most common for most applications. Super glue is not the answer for viton o'rings.
 
In some of the older Parker O-Ring manuals, they use color to identify their o-rings in use. Brown was for Viton. Other sources we used to buy Viton O-Rings from, they were black. But you could hold up a Nitrile o-ring and a Viton o-ring and could tell a slight shade difference between the two black colors.
 
Another vote for viton. It's the only stuff that wouldn't swell like a fat lip after being exposed to high pressure hydrocarbons.

Sent from my SM-G973U using Tapatalk
 
my experience is you at mercy of oring manufacturers, on a printing press using many types of solvent i found often rubber any type is not 100%
.
that is often rubber has recycled content mixed in and if you test rubber in chemical you might find from batch to batch some swells or is effected more than others.
.
asked manufacturer about chemical makeup data on rubber or guarantee it was 100% type i wanted and was told unless you special ordering many tons the rubber you get has no guarantee its 100% of any rubber type
.
rubber color can vary cause filler material mixed in rubber if graphite used it black, literally you can buy black teflon. its black cause its got graphite mixed in to make it electrically conductive to prevent static buildup and discharge which could cause a fire on a solvent machine. filler material mixed in rubber could also be told its a secret recipe or proprietary info. talc another common filler is white color. just like paint percentage of mix effects color
.
filler material mixed in rubber often used to help prevent sticking when its molded. just saying its like concrete (mix) of cement, stone and sand, its a mix, rubber not 100% rubber
 
Watch them mixing rubber in a mill and the stuff that is poured in, in buckets full. Makes you wonder if that crap will mold or not afterwards. Viton compound by itself has a very short shelf life, onced mixed, it will start curing on it's own if not kept refrigerated below a certain temperature. I don't know the exact temperature, but is pretty cold in the storage room. Lighting is provided with special non-ozone producing bulbs. Once molded, the molded parts, O-Rings, are post cured in a high power microwave oven for a number of minutes. Interested what's involved using Viton or even Flourel compounds in molded parts. Sorry, a little bit out of the scope of the thread. Ken
 
The buckets full of stuff are probably the accelerants - the things they need to take the gummy polymer base and turn it into cross-linked rubbery stuff. "Buckets" would be a pretty big batch - I watched a 20kg batch of Viton get mixed up last November, and they used about a quart-sized plastic bag full. It got mixed up in a screw machine mixer, it was essentially a 3 foot diameter motor (50 hp+) directly attached to a pair of wide paddle screws in a little mixing chamber, and that was the whole thing. The amount of power density in that machine was staggering. The rubber mix would cause the whole unit to bounce and shake while it was being churned.

After that, it gets rolled out into sheets and sliced into preforms and used. You are correct that at this stage room temperature storage can start the curing process, so it typically will get used within 1-2 days, if not immediately. Viton/FKM does need post cure, but I've never heard of a microwave oven to do the job, it's usually a large forced air convection oven.

Also, once the molding process is done the rubber is permanently, fundamentally changed on a chemical level, so if any of the molded scrap is recycled and reused, that is a serious cut-rate manufacturer and should not be trusted for any kind of sealing devices. Scrap from the preforming process when the uncured material is rolled out into a sheet and the sheet is trimmed can be re-mixed, but that is usually kept to 10% or less at reputable places.
 
recycled rubber mixed in i have had trouble with before. for example there is sulfur cured and peroxide cured epdm rubber. peroxide cured is more resistant to certain chemicals.
.
i have had batches of rubber go wavy or distort in days rather than months. definitely not same rubber. even when told all batches rubber peroxide cured. only thing we could think off is its a recycled sulfur cured edpm mixed in with the the peroxide cured rubber
.
when i asked about exact chemical analysis of epdm rubber i was told about recycled rubber mixed in and secret recipes or proprietary info of rubber manufacturing is secret. unless ordering tons it was none of my business. i ended up buying electrically conductive teflon instead cost a lot more but it lasted for years rather than days or months
 
Watched several programs on "How it's Made." I watched people making tires and various rubber and similar based materials and slicing a bag of stuff open and pouring it into the mix and tossing the bag in along with it. Wonder if Any of Us would like a grungy, unknown material, who knows what else, bag mixed into their tires. Same thing might be causing some of the problems talked about here.
 








 
Back
Top