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| producing a hermetic seal with dissimilar plastics |  | ||
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| Posted by: darcy ® 05/04/2008, 21:55:11 Author Profile eMail author Edit |
Hi, I am trying to produce a hermetic seal around a 3 hose (PU 85 shore A) extrusion fitting onto 3 nipples in PBT/PC. I currently have used a barb fitting and seem to be ok even with high pressure >170psi. I am concerned about fluid loss over time with just the barb so am thinking about also using adhesives. I wanted to use a plastic weld, ultra sonic/laser/vibration but have stumbled at every method do to the dissimilar materials. Any ideas???
Cheers Modified by darcy at Mon, May 05, 2008, 01:36:52 |
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| : producing a hermetic seal with dissimilar plastics -- darcy | Post Reply | Top of thread | Forum |
| Posted by: Kelly Bramble ® 05/05/2008, 08:09:34 Author Profile eMail author Edit |
I'm assuming that 170 psi is your maximum operating pressure. Can you use a different interface? If you redesigned the interface for a pipe thread you could use teflon thread tape or thread sealer. Another possibility is a threaded type interface with an o-ring to seal. Ofcource it is possibile to combine the barbed interface with an o-ring or thread. |
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| Posted by: Kelly Bramble ® 05/05/2008, 16:20:44 Author Profile eMail author Edit |
Another idea! Can you use an external clamp or other compression device to better secure both parts together at the barb interference location?
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| Posted by: darcy ® 05/05/2008, 20:50:40 Author Profile eMail author Edit |
Thanks for your feedback.
I can't do much in the way of changing/threading the interface as the hose extrusion is one hose with 3 channels (like 2 fig 8's) and the manifold is one molding. The compression clamp is a nice idea. I just got some feedback from Leister (laser welding) in the US and they can weld this type of fitting as long as the lazer is perpendicular to the weld seam. They do however want to change material ot PVC or PE or PP. i'm not too confident that any of these will perform at 170psi(max) for 5+ years (our warrenty)? The ID of each hose channel is only 6mm. |
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| Posted by: Kelly Bramble ® 05/06/2008, 08:14:41 Author Profile eMail author Edit |
I have never laser welded polymers, however I have laser welded ferrous and nonferrous metals. In general I have had good experiences with this form of manufacturing. In general there will be a learning curve on the manufacturers side to obtain a consistant quality weld. |
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