RE: [PSUBS-MAILIST] Not annealing, was: Shrinkage of plexi windows.

["Emile van Essen" <emile@airesearch.nl>]

We usually not built subs for deeper that 1000 meter and annealing is a
painstaking process. 

What if not annealed?? Reduce calculated operational depth by 20%??
Within team Euronaut we did not anneal.

Many of the papers and tests on  Acrylics ore from some years ago. I is
likely that modern production processes make acrylic with lesser stress.
Anyone knows??

Regards, Emile


-----Oorspronkelijk bericht-----
Van: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] Namens Jon Wallace
Verzonden: maandag 30 maart 2009 0:53
Aan: personal_submersibles@psubs.org
Onderwerp: Re: [PSUBS-MAILIST] Shrinkage of plexi windows.


Ok Frank, I got my Stachiw book.

Page 834, third paragraph.  Stachiw says the dimensional change from 
annealing "may exceed in some cases 2 percent of original dimensions".  
He goes on to say, "Such a change may be unacceptable for acrylic 
articles machined to dimensional tolerances of < 0.010-in (0.25mm)."  He 
also suggests reducing the internal stresses to less than 200psi prior 
to initiation of machining operations.

There's no mention of which cases may exceed a 2 percent dimensional 
difference.  It's not something that can be calculated and I suspect 
since your thru-hulls are already installed you're just going to have to 
give it your best effort and hope it comes out ok.

Jon






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