Is all UHMW either extruded or sintered in its construction? Or is that an extra step that is taken in order to allow the plastic to bond well with wax? I ask because I can pick up some UHMWPE pretty easily in my town but have no idea if it is extruded or sintered.
Also, how thick does one typically buy their base and topsheet plastic to be? I read somewhere that neversummer snowboards use ~1/8" plastic for their base however i noticed that snowboardmaterials.com has substantially thinner base materials. As for topsheets thickness I have no idea.
And by the way - great site guys - you are really doing a great service here for ski enthusiasts!
The base material is usually 1-1.2mm thick. This is fairly standard and the edges are made to fit this. If you used other material, you would have to get special edges. Also UHMW is very heavy and a snowboard made of 1/8" would probably weigh 30lbs.
Most common uhmw is extruded and the sintered is specialized for the ski/snowboard industry. Extruded will work, but sintering creates tiny pores in the plastic, which allows the wax to soak in and make a fast base.
All UHMW is sintered, which basically means molded without melting. UHMW and PTFE are intractable polymers and have a zero melt index, therefore need to be "sintered", or basically compression molded. HDPE is a melt processable material and is extruded. The process is determined by the product, and not a choice made by a manufacturer to impose a particular group or properties or characteristics, which are inherent to the molded material itself.
I've been away for a few days and missed that you had recently come on board at Skibuilders. It's really great to have you as part of the group. I hope you'll be a frequent face. Thanks for the great info thus far.
camhard wrote:why do you question what he has said? (example of potential misinformation...)
Well, it first struck me as odd that someone joins, and then makes 4 relatively simple posts about base material (even thought that would be within his field).
But, it seems like everything that I have read to date has indicated that Corona Discharge Treatment is better then flame treating, and is likely what is used in industry.
The following was taken from the :Bond UHMW/PE" forum.
garye@crownplastics.com wrote:Flaming will work significantly better than corona treatment, which is usually used on melt processable materials and thin films to eliminate melting and distortion.
It seems like base material would fall under the heading of "thin films".
I've put many hundreds of hours into research regarding polymer surface treatment. That much time still doesn't make me an authority on the subject, but I have a pretty good sense of the pros and cons of the various treatment modalities. I am quite certain that corona discharge is not used for surface treatment of UHMW ski bases, mainly because corona surface treatment degrades very quickly... like over an hour or two. When corona discharge is used, it is recommended that bonding operations take place no longer than 1 hour after treatment, and preferably within 30 minutes. Flame treating, on the other hand, can result in a surface treatment that bonds well for a couple of years after treatment, though recommended time periods are more in the range of 6 months. Corona treatment is significantly more expensive than flame treating and corona treatment creates ozone that must be contained and neutralized so that it does not become an atmospheric contaminant.
When Garye uses the term 'thin films', he is likely referring to substrates that are in the range of 10 mils or less, like mylar VCR recording tapes that must be surface treated before the magnetic coating can be applied. Films this thin would distort or melt if they were exposed to flame treating.
Yep, base material does just happen to be Garye's field, which probably qualifies him as an authority... nothing odd about his ability to make clear, concise, and 'simple' statements regarding materials that he works with everyday. We're quite lucky to have him contributing. Let's not chase him away by making him feel less than welcome.
I know this is quite old but I've had experience with this and it may help some forum lurkers someday. I am no expert but let me tell you this. I have made boards with corona treated bases and they definately don't hold up near as good as sanding/flaming. And yes, snowboard base material is considered a thin film. Gary knows what he's talking about.
