Re: [PSUBS-MAILIST] Acrylic laminating

["adteleka@in-tch.com" <adteleka@in-tch.com>]

That sounds good but it?s not what really causes this material to need a
post heat treatment.
 
It is pretty much impossible to completely remove all stress from a part.
When the initial annealing takes place the material is quasi-purged of
water and\or gas bubbles and at the same time the material is relaxed of
internal stresses caused by removing the surrounding material that allowed
you to make the window round or in whatever shape needed prior to
machining. 

Then when you make your final cuts with machining, you again have removed
some material and the part is no longer in a quasi-steady state. This time
you have removed less material then when the windows were first cut out of
the sheet by you or the manufacturer meaning internal stresses created this
time will be less and so less post heat treatment is required.

Statics tells us that for equilibrium to exist the sum of the forces equals
zero. This doesn't mean there are no forces; they must just be opposite
each other. Remove or add a force (in our case some material) and something
has to happen or be done to counteract it.

Adam

Original Message:
-----------------
From: Dan H. jmachine@adelphia.net
Date: Fri, 16 Jan 2004 09:01:44 -0500

If you think about what happens when your machining anything, there are
very high temperatures created at the tool tip.  This heat is concentrated
at the surfaces being machined. The interior of the part gets warm but
isn't heated to the surface temp at the tool tip.  The post machining heat
evens this out.   


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