What type of plastic line for this application?

[blueandwhiteg3]

I'm trying to work out the best type of plastic line for an application requiring good sustained load properties, minimal plastic or elastic deformation under operating conditions, good UV tolerance. If possible, it would be transparent, translucent, or at the very least white in color.

For operating conditions, it will be underwater, exposed to direct sunlight, and under a sustained load of around 60 kg. Elasticity and stretch must be minimal. Operating temperature range would be about -12° C to 45° C.

My needs sound a lot like a high-strength fishing line. But most of those lines don't really provide good data on elasticity, UV tolerance, effect of temperature on strength, etc.

A lot of high tension polymer fiber based ropes are out there, but they tend to be drastically overkill for my application - the load values and diameters are grossly larger than I need, and consequently quite expensive.

Any suggestions on what / where to look for the kind of material I need?

 

[NunoH]

Have you considered carbon fibre? I am not familiarised on it being used on its own, but perhaps would meet most of your requirements. Not the translucency, of course, but I doubt any of the proposed, except Nylon will.

I think Dyneema might be a material to look into, as well. I totally agree with Pat regarding contacting DSM.
UHMWPE is used in prosthetics, for hip-joints replacements, and, genearlly this type of prosthesis is aimed to last 10/15 years. And it has to survive the amazingly hostile environment in the body, which includes the frequent and, some times prolonged loading of the parts.

Concerning strain, it is really convenient that you aim for very low values, because polymeric fibres contain highly orientated molecules and won't "give in" much.

I don't know the application, but it might be more cost effective to go for a cheaper material, but sell the product at a cheaper price. Not so environmentally friendly, but might be better.

But if you want to achieve such a low material cost, metal, as SincoTC mentioned, should be considered. For that you would have to check if the pulley system materials would be able to cope with metal. If the metal string went through plastic rings, youo would have a problem.

By the sound of it (particularly the translucent part), you want a fishing line for medium-sized fish. :]

"Ask DNA"

 

[Demon3]

A friend of mine did a post-doc on UHMWPE for hip joints. They radiation cross-link the material to give the good creep resistance. That's actually a pity as it degrades the PE.


Chris DeArmitt

 

[blueandwhiteg3]

Thank you for the constructive replies.

I'm really interested in carbon fiber. I think it may have just the properties I need. The applications I've seen it used in all would seem to specifically rely on its unique creep resistance and strength.

I'm going to look into carbon fiber further, as I know I have seen even fabrics and whatnot made of it, so I suspect it may be quite cheap.

For the moment, I'm setting Dyneema aside. Contacting the maker may help with some data, but Dyneema seems a bit expensive even if the creep values were significantly improved over lower quality products. If carbon fiber proves a dead end, I'll come back to Dyneema.

 

[NunoH]

Being subjective: Carbon fibre is awesome.

I don't actually know monetary values, but I think Patprimer might know a bit. But it should be expensive.
As carbon fibre is used a lot on composites, I suggest for you try the composite engineering forum in this website.
Just a small comment: There are several types of carbon fibres (High strength, high modulus, etc), so you should bear in mind this.

there is another fibre yuo can try, which is a PU. I can only remember one of the commercial names, which is M5 (developed by Magellan and Dupont), but there was anotehr brand. Maybe our materials experts know it.
The problem is taht it is not wide spread and it is expensive.
Ye, I know...Not much help. At least you get to know another high-performance fibre.

Still regarding Dyneema, perhaps yu should use concurrent engineering ( ) and contact DSM, while looking for alternatives.


"Ask DNA"

 

[patprimmer]

Aramid, Carbon and Gel spun PE are all quite expensive. I am out of date, but carbon was the most expensive and gel spun PE as the cheapest, but hings can change a bit over 10 years.

Carbon is generally classified as carbon or graphite. Graphite is the mor expensive and from memory has the highest modulus.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[NunoH]

Man, how old are you Pat?

I am not quite certain if nowadays carbon is still the most expensive, due to the increase of capacity.
I know the price peaked a few years ago (maybe between 2003-2005), because of Airbus and Boeing.

There are several E-moduli for carbon fibre. The most common is about 230GPa (all you americans fetch a converter), but you can get as high as 900 something GPa. But, of course that strength and strain suffer.

http://en.wikipedia.org/wiki/Carbon_Fibre

It contains a few suppliers, as well.



"Ask DNA"

 

[blueandwhiteg3]

I am trying to find some prices from a distributor or online retailer and not having a lot of luck. I'm finding tons of fabrics, but not cords/ropes/lines.

I want to just buy a moderate amount (a few thousand feet at most) at first, so I'd prefer not to try and deal with the manufacturer quite yet.

Anybody have ideas on who might sell it directly?

Pat, the primary motivating factor for carbon fiber from my view is that it should have drastically lower creep. This means I will need less of it than other materials where I need to design to a tiny fraction of capacity to avoid creep issues.

I also came across fiberglass cords. I wonder how they do with creep?

http://www.davlyn.com/products/product.php?id=3&gclid=CNO85of6spcCFQQRswodtVRYjQ

 

[patprimmer]

I've suggested your best course of action in my opinion. You choose not to do that. I can't help any further.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[blueandwhiteg3]

Pat,

I'm appreciate all the effort you've put into generating suggestions, and I'm not trying to devalue your advice. I just need to find time during business hours to contact the local DSM office, hence my not trying delve into it further online. I have an email pending to DSM, but I have not heard back yet.

I have wondered about Zylon, a thermoset polyurethane similar to various aramids in terms of strength it seems. I can't find a lot of data on the cost of this product.

I was eyeing up polypropylene and polyester ropes and noted that 1/4" ropes can be head for under $0.04/ft in roll quantities at retail. Their safe working load looks to be suitable.

Of course, this is pretty huge stuff for such a small load versus what might be possible with other materials. UV tolerance may be an issue with PP, and creep has to be resolved, are there any other reasons I should not consider PP?

Polyester also seems promising, it is considered to not stretch. I don't know about creep, however. UV appears not to be an issue. Are there any other reasons I shouldn't consider polyester?

Chris, you posted some nice numbers on creep stress. Can you give me an indicator as to how to apply the numbers?

Are these numbers that represent a threshold below which there's no creep, or simply a number that represents a creep of a certain amount?

Creep Stress Yield Stress
LDPE 2.1 MPa 8 MPa
HDPE 5.0 MPa 27 MPa
PP 5.0 MPa 25-34 MPa
ABS 6.3 MPa 48 MPa
uPVC 10-12 MPa 50 MPa

 

[NunoH]

Hi guys.

First, Pat I didn't mean to be disrespectful. I surely would like to have the knowledge you have on materials.
Do you deal with natural fibres?

I am not really certain about distributors/retailers for carbon fibres.
Generally, you can find yarns of carbon fibre as they are used for Filament Winding process.
if you don't a awful lot, perhaps you can ask the manufacturers for samples.

As I mentioned before, you should consider asking these questions in the Composite Engineering forum in this website.

Blue&white: The M5 fibre I mentioned is similar to Zylon and, I actually wanted to name the latter.
Similarly to M5, you should have a lot of difficulty in finding data for the material.

PP and PET will always creep. And I believe they would more creep than Dyneema, for instance.

Creep stress should be the stress value at which below of it you would not see any creep.

"Ask DNA"

 

[patprimmer]

I've suggested your best course of action in my opinion. You choose not to do that. I can't help any further.

If this was seen as a hissy fit by me, it is not. It is a simple statement of fact with no intention to imply emotion

I am 61 years old and once again I consider my age a simple fact and attach no emotion to the number.

My initial study and work was in the textiles industry in colour application, but I soon moved to the plastics industry. I eventually reached a position where had some responsibilities for both plastic, apparel and high tech yarns. This was with Akzo Nobel and DSM. I have not ben involved with yarns or Akzo Nobel since 1995 nor DSM since 1997.

My experience with natural fibres stopped in 1977, although I ecxpect they have not changed much.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers for professional engineers

 

[Demon3]

Right, the creep stress is the stress below which there should be "no" creep. In reality there is likely to be some creep at almost any stress if you wait long enough but for practical purposed you can ignore it.


Chris DeArmitt

 

[NunoH]

Wow Pat. Congratulations in the sense that most senior (wiser) people don't generally use the internet, at least for fora.
I did Polymer Engineering and at (and before) the first year of my degree I wanted to go and work for Dupont (because of the high performance materials, such as Kevlar). After changed my mind, as , among several other reasons, I would not like to move to the US.

I think we left out glass fibre from the spectra of choices. Blue&white: you should be able to get plenty of info on these.

Chris: I left out that part, because blue&white seems a bit paranoid about creep. hehe

Nuno


"Ask DNA"

 

[Pud]

NunoH: I hope you are not taking the p*ss from your elders..

I am older (but not much wiser!) than Pat..

Your desire at one time to work for DuPont (grey suit, shiny brown shoes) gives you no Brownie points at all on this forum.

Respect your elders - for we have been there, done it, smoked it and got the scars to prove it.


Harry

ps: Any idea how to set a moulding press up on a new tool?

 

[NunoH]

Harry: No, I wasn't taking the piss. I was merely saying that I was positively surprised.

I don't see how the desire to work for a particular company would give any points.
As Pat described a bit his background, I felt impelled to do the same.
So, Dupont personnel is a bit like the US federal agents, wearing "standardised suits"?

I do hope you guys stay about, because, as I mentioned in Pats case, I sure would like to have his knowledge on materials, although 1/5 would be very nice already.

Regarding your question, I am afraid that I cannot be much help. But, I would suggest for you to open a new thread with the matter and further explain a bit more.

"Ask DNA"

 

[Pud]

Dyneema + Vectran small diameter and cheap here:

http://www.bcyfibers.com/technical_sheets/2008 catalog 12-07C spread 2.pdf

The "452X" looks promising

Some creep data for Vectran here:

http://www.vectranfiber.com/creep.asp

These fibres are often under continual tension when on a compound bow.

Cheers

Harry

 

[btrueblood]

"ps: Any idea how to set a moulding press up on a new tool? "

Put tool on floor. Lift press and place on top. Go have a beer and celebrate.

Or am I missing something?

Harry, do you shoot compound bows? Been looking into making an acquistion of a couple for awhile now. Next you'll tell me your company molds them, and I can purchase the parts cheap from you on ebay. Speaking of which, I still owe you some photos from a kayak trip I took awhile back, have not forgotten, just seem to never have time.

 

[Pud]

Apologies to the op - this is degenerating completely off topic (again).


Ben:

You forgot stage 1: Put on support truss. And you missed the "s" off beer!

Bows, afraid we don't mould them! Just bought 2 (USA/Browning Micro Midas') for the kids. Fancy one (adult) for myself though, but might treat myself to a traditional English longbow for xmas firstly.

http://www.bickerstaffebows.co.uk/proddet.php?cat=Standard&prod=5

Photo's would be nice but no rush...hope blades were ok.

Harry

 

[btrueblood]

Beers...mmmm.

Blades worked extremely well, we (well, really, me) kept up with the guys with fancy carbon fiber shafts (but smaller area blades) quite nicely. And when we raced...well, we kicked everybody else's butts; the bigger blades could really dig in, and the two-man shell is just more hydrodynamic than 1-man shells, methinks.

 

[blueandwhiteg3]

Thanks for all the information, everybody!

I am still trying to get ahold of all these possible suppliers to track down the exact data, pricing, etc. on everything but I will report back when I reach a conclusion.