on bonding ptex sidewalls, and delams

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numpty
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Location: La Crescenta CA

Flame treating UHMWPE

Post by numpty »

First time post and new to ski building. I have been reading as much as I can before I assemble my first pair. The delam issues sounded bad news and i did not have any confidence I could pull it off so I tried a few tests.
I epoxy'd 4 pieces of ptex sidewall to a peice of scrap poplar.
1) the factory treated edge.
2) a saw cut edge flame treated with a plumbers type torch using the end of the blue part of the flame, where it kind of goes yellow (in the dark).
3) as above but I first roughed up the edge with a sharp file.
4) roughed up edge and flame treated with small torch, the kind used for soldering wire not pipes. It had a flame adjustment that allowed more air in the mix giving me a small (5mm) yellow tongue at the end of the flame. I had it turned way down so the flame bent up under its own heat. I used the yellow part and passed it 5 or 6 time over the ptex.

Short answer, both 1) and 4) ripped the wood apart before the joint gave up. 2) and 3) both broke cleanly away (with some significant force I have to say).
I cleaned all joints with acetone before flame treatment.
I am going to repeat the test before I build my boards just to check I have something more scientific than a fluke.

hugocacola
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Post by hugocacola »

hello guys

Back to this topic...

i am building alot of boards and the delamination only happen to me on the begining the first 2 boards, then i was treating the ptex and seams to be good never delam...

but as gman says the petex bond well if you have a consistent process...

what i wondering to know is: what distance the flame should be away from material and how many passes..

At radical snowboards we can see 1 way and about 10cm away from the ptex...

http://www.youtube.com/watch?v=bji8lgksfLA

Any one has a word to give on this??

last time i build cores and attach the sidewall it glue perfect, a strong bonding, but on profiling with the wood planner the thing some times turn bad... it starts delam... and i take them of without to much strength...

i start thinking what i did wrong this time, to fast pass, to colse, to many times????

i start get bored with this stuff....

hugocacola
Posts: 191
Joined: Thu Mar 22, 2007 8:00 am

Post by hugocacola »

is missing some posts here!!!! what a hell...

i had done some tests in small pieces, 1 pass, 2 passes, 3 passes, 4 passes.
where do you think io get the best results??? 2 passes... can you imagine it??

so the other think i want to discuss with you guys is about the gas type. all we know that the propane is the best one because has more power and gives always the blue flame consitently. and all we know that the normal flame torch has a mix of 80%butane and 20% propane... so i think here we could have some problem...or not.

Anyone to disagree with me??

sammer
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Post by sammer »

hugo
While I've never done it myself, ( I'm gonna stick with maple for my sidewalls), I have done a lot of gas welding, cutting, brazing etc.
The idea is to oxidize the surface.
The blue part of the flame contains very little oxygen.
The fan of the flame beyond the blue cone ( not very visible in bright light) is the part that has the greatest amount of oxygen.

This is from Advanced Adhesion Inc. aka mr. sticky's poly bonder

"To flame-treat an off-the-shelf propane torch with a flame spreader is the tool of choice. This tool, when
run near max flame, offers a two-part flame. Adjust the torch so that the hottest portion of the flame near
the torch nozzle that is very blue remains within the confines of the flame spreader attachment. The
secondary flame, which is the "oxidizing flame" should now extend beyond the flame spreader
approximately 1-1/2”-2" (the secondary flame is difficult to see unless in a darkened room).
The idea behind the flame treatment is to make electrons available for sharing in a chemical bond. This
is accomplished by oxidizing the surface. This is not detrimental to the PE or HDPE structurally and
does not change the color. The only noticeable change is a slight difference in the gloss of the surface
between the oxidized and non-oxidized portions of the PE or HDPE. We tested several exposure rates
and determined that approximately 2-3 seconds of exposure seems best. We executed this exposure by
making 5 gentle passes across the area to be bonded."

I think he's saying 5 slow passes = 2-3 seconds of oxidation.

hope this helps

sam
You don't even have a legit signature, nothing to reveal who you are and what you do...

Best of luck to you. (uneva)

numpty
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Joined: Wed Nov 04, 2009 7:05 pm
Location: La Crescenta CA

Flame treating UHMWPE

Post by numpty »

I just tried a test with 4 pieces of sidewall each about 3" long.
I flamed them just like sammer says above but varied the number of passes from 4 - 5 and them all the way up to 8-10.
They all fully bonded to the poplar and tore the wood apart before releasing. The only eareas that were badly bonded were teh corners and that could be bad filing or flaming.
I did make one change to my test, I used a lower pressure clamp. I suspect that a lot of teh issues particulary with sidewall to core delam is epoxy squeeze out. The pex does not absorbe glue and the wood is hard so unless there is a little gap to hold the glue it will not make a strong bond. I put paper shims in the ends of each joint to hold it open and it fully bonded right through the paper and all.
I did here an intersting comment from a guy at Crown about their flame treatment, he said it only lasts about 90 days! If you keep the stuff around our buy through a second party you could get ptex that needs to be re-flamed even on the base or topsheet. If you live in Europe the shiping could eat up the time.
I am begining to get more confident I can do this but maple or bambo is sounding like a better bet.

Telemark Mark
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What about too much PSI???

Post by Telemark Mark »

I've been reading through all the plastic sidewall info...........trying to convince myself to go that route (as opposed to wooden sidewalls). I thought there was some good info in the TAP Plastics video here:

http://www.tapplastics.com/info/video_d ... =quicktime&

In it they mention:

"It is possible to squeeze out so much glue that the joint is weak. Therefore it is important that the glue remains at least .005" thick in the joint to provide maximum strength."

This might be something we should look into. I've vacuum bagged a couple pairs of skis with UHMW sidewalls (sanded and flamed) and had very good results with bonding. I think Head Monkey was using 50psi with very good bonding. Anyone with mixed results care to share their PSI?

carnold
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Location: Australia, Melbourne.

Post by carnold »

Hi.
I've never had any delams with my UHMWPE sidewalls in snowboards. Here's what i do. Belt sand with fresh 100 grit belt until all the original surface is removed. Flame with a propane torch. Not to much, not to little 2 passes (one north, one south) at 10 seconds for the length of 1500mm. Glue with epoxy. Clamp but not too tight to the core. Vac bag the whole thing with a top plate (this is 4 layers of 3 mm mdf laminated in the mould). All good so far, touch wood!
I also had a long discussion with one of the polymer engineers here at work (TAFE college) a long time ago and he suggested sticking a layer of glass tissue to the UHMWPE before joining to the core. Something like this. Heat the surface of the UHMWPE until it is just molten. Then using a stainless steel roller press the tissue into the surface of the UHMWPE, flame treat and then bond.
I have never tried this as it has always worked without but it could help if you are having problems.
C.

Telemark Mark
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Post by Telemark Mark »

Carnold,

You mentioned:

"Vac bag the whole thing with a top plate (this is 4 layers of 3 mm mdf laminated in the mould)."

Can you explain what you're doing here? What is the mdf top plate?

I sand with 80-100 grit and then flame prior to vacuum bagging also. No problems thus far.

-Mark

carnold
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Location: Australia, Melbourne.

Post by carnold »

Hi. When I first started making side wall boards after making cap boards in the vac bag I noticed that a small bump of resin was forming along each side under the PBT topsheet. To stop this and get a flat topsheet I made up a male part for the existing mould by laminating 4 layers of mdf on the mould with a core blank between the female and male mould sections. The top (male) mould is pressed onto the board which is assembled on the female mould by vacuum I'll take some photos next board (that won't be for about 10 weeks) and post.

heliski989
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Post by heliski989 »

G-man wrote:Doug,

Crown obviously has it down really well as seen by how well their base material bonds to the bottom composite layer. I always thought it would be really enlightening to visit the Crown factory and take a tour to see how they do their surface treatment and quality control. I would be great if somebody who lived close to the Crown factory could take a tour and post a video.



G-man
So, I have been in this tour. I can not comment on the sophistication and process of their flame treatment out of professional courtesy. But i can guarantee you that DBS is correct, it is simple and can be done with a torch.

Crowns material is also specific for bonding. They use less than half of the mold release used in standard UHMW. Hence, if you are having delam problems and are using uhmw form somewhere other than crown i would rethink what you are doing.

- JT

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redbull
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Post by redbull »

heliski989 wrote:Crowns material is also specific for bonding. They use less than half of the mold release used in standard UHMW. Hence, if you are having delam problems and are using uhmw form somewhere other than crown i would rethink what you are doing.
Of course Crown has their process down, but I always wondered if Crown's UHMW has a slightly different composition for bonding. Great info heliski! So that brings to question what kind of UHMW are you guys working/testing with? Head Monkey made it clear he uses Crown. Are the others (doughboy, carnold, hogucacola, knightsofnii, etc.) using just locally bought UHMW? Is anyone getting consistent bonds with local UHMW (eg. not Crown UHMW)?
doughboyshredder wrote:pourable urethane is one that I want to try. http://www.eagerplastics.com/ure.htm

pmc790 is a 90 durometer urethane which could be applied to the core along with a primer. Or possibly applied after pressing, by routing out a void to be filled with the urethane.
Doughboyshredder, did you experiment with urethane? This is of interest to me. Have you seen Ride Snowboards tech video: http://vimeo.com/2429346
I wonder if any treatment is needed for the use of urethane sidewalls? If so, what kind of treatment? Primer?

carnold
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Location: Australia, Melbourne.

Post by carnold »

Hi Rebull.
I'm using www.roechling-plastics.com Polystone 7000 supplied by Dotmar plastics. I've had no problems with both sidwalls and tip/tail infills. Both are from extruded sheet 9 mm for sidewalls and 2 mm for infills. Sanded and flammed. C.

knightsofnii
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Post by knightsofnii »

after tearing apart 36 different samples of fully laid up sections: base, glass, sidewall, glass, another piece of base.

I determined that a LIGHT sanding on the grindrite 80 grit, plus two med/slow passes with a flame tip, was the best for bonding. In these tests, the samples failed within the fiberglass itself, though it was still not too difficult to pull apart. But like I said it was the glass that failed.

I finally built a board where the sidewalls held up, even after the board was flexed to failure. however...

We also made test samples with bamboo v-lam plywood pieces, sanded lightly. This. Was. Way. Stronger. Than. All. Plastic. Samples. Combined.

Bamboo and other woods eat glue, plastic repels it. Wood requires more finish work but will hold up. bamboo > uhmw = :)

If I were building for myself, I'd take the chances with flame treating plastic etc because I think ptex sidewalls are neat, especially in pink and neon colors with lots of black in the top/bottom graphics. However, we're going for quality and we dont want boards coming back from sidewall delams, its been our biggest issue, we're eliminating it.

For some of you still experiencing sidewall delam issues. I'd suggest trying the following:

Change your design from full ptex sidewall to what i call the "cap-wich" design. ie: new K2 boards, some old Palmers, etc.

Use the Crown 2mm tip fill material that's already factory treated, design a mellow cap down to this 2mm sidewall that is pretty much guaranteed to bond as long as you keep it clean.

You'll need either the 3d top mold if you're using clamp or pneumatic press... or, you can use the airbag itself as your top mold. Get a wider airbag is all.
Doug

Telemark Mark
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Post by Telemark Mark »

knightsofnii,

Can you fill us in a little more on your "cap-wich" idea? Are you suggesting laminating a 2mm strip of tip/tail spacer to the exposed wooden sidewall?

Edit: After rereading your post I think I understand now. I think you mean to actually have a "capped" ski where........in this case.........the topsheet material would roll over the chamfered wooden sidewall and tie into a 2mm tip/tail spacer strip?

If I'm correct, how would you initially attach the 2mm strip to the core prior to layup and profiling?

You've got me thinking.

knightsofnii
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Post by knightsofnii »

K2 does it on their new boards. Just a narrow strip of tip fill along the rails instead of thick sidewall. But you gotta cap down to it. Ill draw it when I get home
Doug

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