FRN Strength / Durability

[Airlsee]

A few recommendations for adding to your FRN testing/collection...

[N. Brian Huegel]

https://www.ptonline.com/blog/post/dupo ... polyesters.

[DeadForests]

https://www.ptonline.com/blog/post/dupo ... polyesters.

From what I can gather from this, it means that FRN should be heat resistant. I think this makes sense, as I don't really recall hearing anyone saying their FRN melted unless exposed to open flame levels of heat.

I think G10 is also not totally flame proof as I do recall seeing a picture of a g10 handle after a fire. It separated and looked like an old phonebook.

[The Deacon]

https://www.ptonline.com/blog/post/dupo ... polyesters.

From what I can gather from this, it means that FRN should be heat resistant. I think this makes sense, as I don't really recall hearing anyone saying their FRN melted unless exposed to open flame levels of heat.

I think G10 is also not totally flame proof as I do recall seeing a picture of a g10 handle after a fire. It separated and looked like an old phonebook.

I would not call FRN "heat resistant". Granted, you could autoclave an FRN handled knife or drop one in boiling water without issue, but it does not take an open flame to get it soft. If, for example, if you try to drill it with an electric drill, sand it with an electric sander, or even sand it overly vigorously by hand, it will get gummy. Placing it on a hot burner on an electric stove will melt it, and at least one guy who use them for work has put his initials on FRN knives with a soldering iron.

[DeadForests]

https://www.ptonline.com/blog/post/dupo ... polyesters.

From what I can gather from this, it means that FRN should be heat resistant. I think this makes sense, as I don't really recall hearing anyone saying their FRN melted unless exposed to open flame levels of heat.

I think G10 is also not totally flame proof as I do recall seeing a picture of a g10 handle after a fire. It separated and looked like an old phonebook.

I would not call FRN "heat resistant". Granted, you could autoclave an FRN handled knife or drop one in boiling water without issue, but it does not take an open flame to get it soft. If, for example, if you try to drill it with an electric drill, sand it with an electric sander, or even sand it overly vigorously by hand, it will get gummy. Placing it on a hot burner on an electric stove will melt it, and at least one guy who use them for work has put his initials on FRN knives with a soldering iron.

But it does say in the article that it was resistant to things such as hot oil.

[DeadForests]

Hi Deadforests,

FRN is /fiberglas reinforced Nylon. It'a made by a number of manufacturers. "Zytel" is a brand name for Dupont FRN. There are other makers also.

We've been using it since 1990. I think you need to purchase an FRN model and see for yourself.

sal

Hi Sal, I have a Para 3 LW and have owned many FRN models and they have proven their strength. I still didn't really get the answer I wanted to get unfortunately. I want to know, has Spyderco done any strength tests with FRN, and would you care to share any findings? I think FRN is much stronger than people give it credit for.

[The Deacon]

But it does say in the article that it was resistant to things such as hot oil.

Guess that would depend on how hot the "hot oil" is. 250º F, no problem. 300º F, maybe. Much higher, I wouldn't risk it but YMMV. My observations were based on personal experience and things I've seen on this forum, feel free to ignore them.

[The Deacon]

As for strength, depends on what you're looking at. I my experience, FRN will deform, rather than break. For example, I can take the FRN panel from a Stretch 2 handle, bend it until the ends touch, and it will spring back to flat. If I did that often enough, it would eventually stress fracture, but a G10 or CF panel of equal size and thickness, while much harder to deform, would break long before the ends ever touched. One guy here ran over an FRN Spyderco with a Bobcat, bent the blade, did no appreciable damage to the handle. It just has a relatively low melting point, because nylon has a relatively low melting point. That's what makes it ideal for injection molding.

[sal]

Hi Deadforests,

We've not done break tests on our breaking machine, but we have done an odd test here and there. We broke a few of the plastic clips back in the day when we were making models with plastic clips. (1990-1997) We were replacing knives with broken clips until we learned that people were breaking the clips with a hammer to get a new knife. We verified it was possible and stopped replacing knives with broken clips, we replaced the broken plastic clip with a metal clip screwed into the handle. We drove over an FRN model with a truck. We've sanded some, machined some, dropped them off of 10 story buildings. Enough to know we liked to use it. I do not have an "numbers" to give you. It depends a great deal on the amount of fiberglass in the Nylon. Some company's that we use can accept as much as 65% fiberglass.

sal

[JonLeBlanc]

The two I have (Stretch 2 and Goddard Sprint) have seen fair amount of use with nary a ding.

[Wartstein]

...... It depends a great deal on the amount of fiberglass in the Nylon. Some company's that we use can accept as much as 65% fiberglass.

sal

Now that is really interesting!

Different amount of fiberglass in the Nylon could perhaps also explain what has been discussed in this thread before:
That to some/many people Seki FRN "feels" different to Golden FRN (Seki a bit "softer/tougher/rubber-isher," Golden "harder"/more "brittle"/more plasticy)

[vivi]

But it does say in the article that it was resistant to things such as hot oil.

Guess that would depend on how hot the "hot oil" is. 250º F, no problem. 300º F, maybe. Much higher, I wouldn't risk it but YMMV. My observations were based on personal experience and things I've seen on this forum, feel free to ignore them.

Now I'm considering testing an FRN spydie against 350 degree oil.....for science

[The Deacon]

Different amount of fiberglass in the Nylon could perhaps also explain what has been discussed in this thread before:
That to some/many people Seki FRN "feels" different to Golden FRN (Seki a bit "softer/tougher/rubber-isher," Golden "harder"/more "brittle"/more plasticy)

Could be, could also be differences in the nylon, since it's a "family" of plastics rather than one specific formula, or a combination of those two factors.

Now I'm considering testing an FRN spydie against 350 degree oil.....for science

Fried dragonfly, anyone!

[billdoier72]

I admit that I started out wanting to dislike FRN because of its perceived cheapness. But after carrying a few LW models, I have been won over. It is very light, tough, scratch resistant and impervious to the elements. Your blade will snap before the handle will fail so it's plenty strong. I carry it with confidence.

[DeadForests]

Hi Deadforests,

We've not done break tests on our breaking machine, but we have done an odd test here and there. We broke a few of the plastic clips back in the day when we were making models with plastic clips. (1990-1997) We were replacing knives with broken clips until we learned that people were breaking the clips with a hammer to get a new knife. We verified it was possible and stopped replacing knives with broken clips, we replaced the broken plastic clip with a metal clip screwed into the handle. We drove over an FRN model with a truck. We've sanded some, machined some, dropped them off of 10 story buildings. Enough to know we liked to use it. I do not have an "numbers" to give you. It depends a great deal on the amount of fiberglass in the Nylon. Some company's that we use can accept as much as 65% fiberglass.

sal

This is exactly the answer I've been looking for. I feel like this encapsulates everything I've learned about FRN thus far in my uses. It seems to be insanely tough and lightweight. I don't think it gets enough credit as a material outside of these forums. It always seems like it's a "bad thing" to have FRN. FRN reduces the weight, cost, and keeps toughness at peak. I think you said it best yourself, it was an evolution.

Thanks for taking the time to answer my question until I was satisfied with your answer. I cant imagine how busy you must be.

[DeadForests]

But it does say in the article that it was resistant to things such as hot oil.

Guess that would depend on how hot the "hot oil" is. 250º F, no problem. 300º F, maybe. Much higher, I wouldn't risk it but YMMV. My observations were based on personal experience and things I've seen on this forum, feel free to ignore them.

I suppose you're right. Just makes me curious as to what temperature it can survive exactly. Where the melting point of FRN sits at, might be surprising I feel like.

[DeadForests]

As for strength, depends on what you're looking at. I my experience, FRN will deform, rather than break. For example, I can take the FRN panel from a Stretch 2 handle, bend it until the ends touch, and it will spring back to flat. If I did that often enough, it would eventually stress fracture, but a G10 or CF panel of equal size and thickness, while much harder to deform, would break long before the ends ever touched. One guy here ran over an FRN Spyderco with a Bobcat, bent the blade, did no appreciable damage to the handle. It just has a relatively low melting point, because nylon has a relatively low melting point. That's what makes it ideal for injection molding.

Interesting, so overtime FRN may not look the prettiest but even then it is functional.

[Jason Paul]

It depends a great deal on the amount of fiberglass in the Nylon. Some company's that we use can accept as much as 65% fiberglass.

sal

So in other words, NRF?

Hayoooo! Be sure to tip your servers...

So anyway...

One (probably imaginary) concern I always seem to have, especially with linerless salt models; is the possibility of an FRN (or FRCP) backlock hyper-extending in hard use. Imagine really bearing down when cutting through something, and you feel that little bit of lock rock, but something gives way and the blade hyper-extends, buckling backward. I'm talking about hard-cutting, not prying.

Given the context of this and other similar threads; if this had happened, someone would have posted it by now.

But it did get me wondering; what would be the weak point that might cause this to happen? What would give way first? Some FRN bits around the pivot? Maybe the FRN "channel" the lockbar sits in?

Or, would it not be the FRN at all? In this type of use, I can't imaging the blade or lockbar breaking before the FRN, but I'm also not a materials scientist.

Any thoughts?

[James Y]

FRN's cheapness is only a perception.

One day over 20 years ago, I was on a paved walking trail at the beach, and some guy asked if I had a knife, and could I help him. I suppose he saw the pocket clip of the Delica 3 in my pocket. I'm not 100% on what it was he wanted cut, but best I can recall, it was a zip tie or some type of plastic strap on his daughter's roller skate. I pulled out my D3 and he said, "You sure that plastic knife can handle it?" Almost before he could finish his sentence, I severed the zip tie, or strap, or whatever it was, and he said, "Oh..."



Jim

[RustyIron]

It seems to be insanely tough and lightweight. I don't think it gets enough credit as a material outside of these forums. It always seems like it's a "bad thing" to have FRN.

I've been reading up on this for the past few days. FRN is used on automotive intake manifolds, radiators, gun frames/receivers, high-end athletic shoes, many knife manufacturers' handles, ball bearing cages, and BMX wheels. Whoda thunk these fancy materials ever would have caught on?