<VV> Re: VirtualVairs Digest, Vol 4, Issue 112

[Harry Yarnell]

LOF?
I thought it meant Libby Owens Ford; the manufacture.

Harry Yarnell
perryman garage and orphanage
perryman, MD
hyarnell1 at earthlink.net

----- Original Message ----- 
From: <RoboMan91324 at aol.com>
To: <virtualvairs at corvair.org>; <r.gault at sbcglobal.net>
Sent: Tuesday, May 17, 2005 7:57 PM
Subject: <VV> Re: VirtualVairs Digest, Vol 4, Issue 112


> Roger,
>
> Great post.  The "compression trick" is used in many  applications.
> Pre-stressed concrete is a good example but the one we are  most familiar
with is
> tempered glass.  In the manufacturing process, both  sides of the near
molton
> glass plate/pane is cooled relatively quickly.   This shrinks the outside
glass
> while the inside is still hot.  This is  usually done with oil.  You may
have
> noticed "LOF" printed on a lot of  automotive glass.  This stands for
"liquid
> Oil Float."  As the inside  cools relatively slowly, it also shrinks.
Since the
> outside has already  hardened and can't really shrink, it compresses.  As
you
> point out, hard  and brittle substances will tend to crack and then
propagate
> that crack if in  tension.  The compressed outside glass is very tough.
You
> may have  noticed the difference between regular plate glass and tempered
> glass if it is  struck.  If you want to break tempered glass relatively
easily,
> tap it on  the edge with a hammer.  The inside layer is in tension and the
crack
> will  propagate.  Wear safety glasses.
>
> Just ask Mr. Wizard.
>
> Doc
> ~~~~~~~~~~~~
> In a message dated 5/17/2005 4:15:58 PM Pacific Standard Time,
> virtualvairs-request at corvair.org writes:
>
> Message:  3
> Date: Tue, 17 May 2005 17:49:49 -0500
> From: "Roger Gault"  <r.gault at sbcglobal.net>
> Subject: Re: <VV> Crank  Nitriding/Engine case question Question
> To: "Corvair List"  <virtualvairs at corvair.org>
> Message-ID:  <00cd01c55b32$bb905d20$6400a8c0 at GaultComputer>
> Content-Type:  text/plain;    charset="iso-8859-1"
>
> Chris,
> <snip>
> As for the nitriding discussion you found, I'm not  impressed.
>
> <snip>
> Nitriding is done to put the surface in  compression.  In order for a
fatigue
> crack to start, it must get the  surface into tension.  Bending forces on
the
> crank can do that.  If  the surface is nitrided, there is a built-in
> compression which must be overcome  before the surface goes into tension.
So, the
> nitriding reduces  cracking.
>
> <big snip>
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