Hey all,
we have had some issues with sidewalls delaminating. We currently use UHMWPE sidewall from crown. We abrade it with 80 grit paper and flame treat it and some of our boards are still having it delam and some are not. Do you guys have any other tricks for bonding sidewall. I was thinking of using a lower grit paper and somehow making the abrading and flaming more consistent because it seems to work on some boards and not others.
thanks!
sidewall delam
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Hi beansnow,
I've written quite a lot of stuff over the last couple of years about the research I've done regarding successful bonding of the UHMW sidewall. Surface treating for bonding is a pretty fine science, and you are right on track when you talk about pursuing a more consistent process... an absolute must if you want consistent results. Basically, you need a flame treating system in which you can precisely control the gas (must be propane) and air mixture of the flame, control the humidity of the surrounding air, and control the flame exposure time and intensity. Then, after surface treatment, you must be able to accurately test the surface dyne level of each piece that you want to bond. If you can truly maintain a consistent dyne level surface tension, you will be able to obtain predictable and consistent bond results.
As it appears that you may have learned, we can sometimes get lucky with our flame treating process via a hand held propane torch, ending up with a ski or two that actually stay together. This can lead to a somewhat false confidence that we have the flame treatment process wired, only to suffer delamination of the next few skis.
If you search the 'G-man' posts from the last two years and look for the one's that have to do with surface treatment, you should be able to find all the stuff that I've written on the subject, along with a bunch of links to various actual industry articles. Surface treatment of UHMW is a tough problem to solve, especially for the small scale builder. I think it's one of the reasons that cap construction gained so much popularity. Now that many of the production companies are going with sandwich construction for some of their models, these companies certainly must be using polymer bonding specialists (and the right equipment) to get the surface treatment process correct.
Good luck,
G-man
I've written quite a lot of stuff over the last couple of years about the research I've done regarding successful bonding of the UHMW sidewall. Surface treating for bonding is a pretty fine science, and you are right on track when you talk about pursuing a more consistent process... an absolute must if you want consistent results. Basically, you need a flame treating system in which you can precisely control the gas (must be propane) and air mixture of the flame, control the humidity of the surrounding air, and control the flame exposure time and intensity. Then, after surface treatment, you must be able to accurately test the surface dyne level of each piece that you want to bond. If you can truly maintain a consistent dyne level surface tension, you will be able to obtain predictable and consistent bond results.
As it appears that you may have learned, we can sometimes get lucky with our flame treating process via a hand held propane torch, ending up with a ski or two that actually stay together. This can lead to a somewhat false confidence that we have the flame treatment process wired, only to suffer delamination of the next few skis.
If you search the 'G-man' posts from the last two years and look for the one's that have to do with surface treatment, you should be able to find all the stuff that I've written on the subject, along with a bunch of links to various actual industry articles. Surface treatment of UHMW is a tough problem to solve, especially for the small scale builder. I think it's one of the reasons that cap construction gained so much popularity. Now that many of the production companies are going with sandwich construction for some of their models, these companies certainly must be using polymer bonding specialists (and the right equipment) to get the surface treatment process correct.
Good luck,
G-man
thanks G-man great info!
That all pretty much makes sense to me. I think we underestimated just how hard it is to bond PE. We were going to try and peel some test pieces on an Instron with some different levels of abrasion and a more controlled flaming but we really dont have the time right now to build a setup to control this to the level you seem to say it needs.
Do you think chaning to ABS would make it easier? Do you still need to treat ABS?
I know crown offers sidewall that you can have custom shaped to your cores and treated on both sides. Its a little pricey but might be worth it for us. Have you ever tried this?
Thanks!
That all pretty much makes sense to me. I think we underestimated just how hard it is to bond PE. We were going to try and peel some test pieces on an Instron with some different levels of abrasion and a more controlled flaming but we really dont have the time right now to build a setup to control this to the level you seem to say it needs.
Do you think chaning to ABS would make it easier? Do you still need to treat ABS?
I know crown offers sidewall that you can have custom shaped to your cores and treated on both sides. Its a little pricey but might be worth it for us. Have you ever tried this?
Thanks!
beansnow,
I've spent quite a bit of time experimenting with flame treating ABS and with bonding ABS, but have never had any luck with either. Also, ABS has such a low thermal softening temperature, shaping/machining it can be a bit problematic. I know that a lot of production and small builders use ABS, so, they must have figured something out that I couldn't. I even experimented with engineering grade ABS samples (about 10 times the cost of regular ABS), but couldn't get it to bond sufficiently either.
I didn't know that Crown was offering custom shaped sidewalls. I know that they do a real good job with flame treating sheet products. I'd think that it would take a whole different machine to flame treat narrow individual side walls, so maybe they took that step. I'm betting that production builders who are using sandwich construction are using this service. If you order custom sidewalls, you can't reshape them in any way or you'll lose your surface treatment and be back to square one with the bonding problems. That means that you can't even route in a metal edge relief groove or tweek your profile just a bit without destroying the surface treatment. Custom sidewalls sound like the way to go for a production builder who is making hundreds of cores that are exactly the same, but it sounds a bit restrictive for the small builder who may want to play around with design parameters.
For the last 18 months, I've been using/testing a special polymer for sidewalls that I'm quite sure that no one else (big or small) has happened upon. I've built 6 pairs of skis with these sidewalls and have abused the skis in every way I can think of in order to get the sidewalls to fail. I've never had any kind of failure whatsoever... no delams, no cracks, no marring or shaving from impacts. This material machines nicely and stays very tough and flexible at below freezing temps. For now, I'm keeping this polymer to myself. It's availability is limited, and if I reveal what it is, the bigger companies will certainly grab it all up and I'll be back to futzing around with trying to get UHMW to bond. It took me a solid year of intense research and testing to find this product and I just don't want to give it up to the big boy's factories in China.
So, in reality, I just don't have much optimistic advice regarding UHMW and ABS. I just couldn't ever get either to bond well. I do think, that with the proper equipment and flame treating procedure, UHMW can be made to work pretty well, but one would definitely have to follow the rules for good surface treatment, of which there are many.
Sorry I can't be of more help.
G-man
I've spent quite a bit of time experimenting with flame treating ABS and with bonding ABS, but have never had any luck with either. Also, ABS has such a low thermal softening temperature, shaping/machining it can be a bit problematic. I know that a lot of production and small builders use ABS, so, they must have figured something out that I couldn't. I even experimented with engineering grade ABS samples (about 10 times the cost of regular ABS), but couldn't get it to bond sufficiently either.
I didn't know that Crown was offering custom shaped sidewalls. I know that they do a real good job with flame treating sheet products. I'd think that it would take a whole different machine to flame treat narrow individual side walls, so maybe they took that step. I'm betting that production builders who are using sandwich construction are using this service. If you order custom sidewalls, you can't reshape them in any way or you'll lose your surface treatment and be back to square one with the bonding problems. That means that you can't even route in a metal edge relief groove or tweek your profile just a bit without destroying the surface treatment. Custom sidewalls sound like the way to go for a production builder who is making hundreds of cores that are exactly the same, but it sounds a bit restrictive for the small builder who may want to play around with design parameters.
For the last 18 months, I've been using/testing a special polymer for sidewalls that I'm quite sure that no one else (big or small) has happened upon. I've built 6 pairs of skis with these sidewalls and have abused the skis in every way I can think of in order to get the sidewalls to fail. I've never had any kind of failure whatsoever... no delams, no cracks, no marring or shaving from impacts. This material machines nicely and stays very tough and flexible at below freezing temps. For now, I'm keeping this polymer to myself. It's availability is limited, and if I reveal what it is, the bigger companies will certainly grab it all up and I'll be back to futzing around with trying to get UHMW to bond. It took me a solid year of intense research and testing to find this product and I just don't want to give it up to the big boy's factories in China.
So, in reality, I just don't have much optimistic advice regarding UHMW and ABS. I just couldn't ever get either to bond well. I do think, that with the proper equipment and flame treating procedure, UHMW can be made to work pretty well, but one would definitely have to follow the rules for good surface treatment, of which there are many.
Sorry I can't be of more help.
G-man
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Cadman
Flame treatment is a good process for UHMW sidewall as well as rough
sanding. One thing to remember is that the surface begins to degrade or
oxidize very quickly so if you flame treat and then leave the material laying around the shop for awhile it will not bond very well. Use the material soon after treating it and you will have better results.
sanding. One thing to remember is that the surface begins to degrade or
oxidize very quickly so if you flame treat and then leave the material laying around the shop for awhile it will not bond very well. Use the material soon after treating it and you will have better results.
G-man: now you've got my interest..... I'm off to the library...G-man wrote: For the last 18 months, I've been using/testing a special polymer for sidewalls that I'm quite sure that no one else (big or small) has happened upon. I've built 6 pairs of skis with these sidewalls and have abused the skis in every way I can think of in order to get the sidewalls to fail. I've never had any kind of failure whatsoever... no delams, no cracks, no marring or shaving from impacts. This material machines nicely and stays very tough and flexible at below freezing temps. For now, I'm keeping this polymer to myself. It's availability is limited, and if I reveal what it is, the bigger companies will certainly grab it all up and I'll be back to futzing around with trying to get UHMW to bond. It took me a solid year of intense research and testing to find this product and I just don't want to give it up to the big boy's factories in China.
Hi bigKam,
Good luck on your search. Sorry I have to be a butt-head and not share the secret at this time. I'm just quite certain that I'd lose my source if word were to get out. One thing that I'll suggest is that you put a sample of any polymer that you are considering in the freezer for awhile, then take it out and do some flex testing and impact testing on it while it's still frozen. Out of the nearly 100 samples that I tested, all but one became too brittle (shatter when flexed) to make the grade at sub-freezing temperatures.
G-man
Good luck on your search. Sorry I have to be a butt-head and not share the secret at this time. I'm just quite certain that I'd lose my source if word were to get out. One thing that I'll suggest is that you put a sample of any polymer that you are considering in the freezer for awhile, then take it out and do some flex testing and impact testing on it while it's still frozen. Out of the nearly 100 samples that I tested, all but one became too brittle (shatter when flexed) to make the grade at sub-freezing temperatures.
G-man
-
knightsofnii
- Posts: 1148
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i want to add something important:
ive sanded lots of durasurf sidewall on every grit of grindrite belt available, and one of the most important things is to sand with water on a clean belt.
keep a seperate "unbroken" belt for sidewall only, you might want to consider using a seperate grinder altogether and no imulsion fluid, just water.
do NOT dry sand, the heat will heat cycle the plast somehow and make it extremely brittle.
try it, sand a sidewall on a dry grindrite and then bend it. if you do it with a wet belt, you can tie the thing into a knot afterwards.
ive also had someone suggest flame treat FIRST, THEN sand. but i have not tried this yet.
ive sanded lots of durasurf sidewall on every grit of grindrite belt available, and one of the most important things is to sand with water on a clean belt.
keep a seperate "unbroken" belt for sidewall only, you might want to consider using a seperate grinder altogether and no imulsion fluid, just water.
do NOT dry sand, the heat will heat cycle the plast somehow and make it extremely brittle.
try it, sand a sidewall on a dry grindrite and then bend it. if you do it with a wet belt, you can tie the thing into a knot afterwards.
ive also had someone suggest flame treat FIRST, THEN sand. but i have not tried this yet.