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<p>Tom and Bryan,</p>
<p>I think I agree with both of you. We want to enable intelligent
digital twins so that they can help shop floor engineers complete
each task as efficiently as possible.</p>
<p>Tools for doing so include real-time manufacturing simulators
(for checking and verification), and intelligent design assistants
for making trade-offs, such as the one cited for the thickness,
material and location of the fasteners.</p>
<p>Therefore, the serial number needs to go in the
product_definition.id because digital twins enable/apply design
changes during the manufacturing.<br>
</p>
<p>Martin<br>
</p>
<div class="moz-cite-prefix">On 7/18/2022 8:42 PM, Thomas Thurman
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:E49E4D40-65B3-4D0C-A983-2F12646C1B42@imonmail.com">
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Bryan,
<div>Thanks for the requirements!</div>
<div>They mirror well understood practice using design constraints
which is about all I can say.</div>
<div>When we add simulation requirements in different domains on
the serial number, the option of putting the serial number on
the product_definition goes away because the product_definition
IS the container for each simulator specific collection of
properties.</div>
<div>I really think we should focus on the functional
requirements.</div>
<div>Just my two cents.</div>
<div>Tom<br>
<br>
<div dir="ltr">Sent from my iPhone</div>
<div dir="ltr"><br>
<blockquote type="cite">On Jul 18, 2022, at 9:36 AM, Bryan
Fischer <a class="moz-txt-link-rfc2396E" href="mailto:brfischer@tdp360.com"><brfischer@tdp360.com></a> wrote:<br>
<br>
</blockquote>
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<blockquote type="cite">
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<p class="MsoNormal"><span style="font-size:12.0pt">Hi
Martin, All<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">I
don’t really care which method is used in STEP as long
as it works with the rest of the design /
manufacturing / quality / etc. space. I do care that
we enable broader application and extend our ability
to simulate more of the product (via twin or whatever
you prefer to call it). <o:p>
</o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Your
description of the benefits of option 2 are
intriguing. I’ve had an idea for some time that I
haven’t created a way to do it. I propose that
specifications, specifically tolerances, could and
should be linked. We do that today in very simple
cases with MMC (MMR) and LMC (LMR) modifiers – one
interpretation of these specifications is that the
size of the geometric tolerance zone depends on the
size of the feature of size; for example, the larger
the hole, the larger the location tolerance. This is
already addressed in 242.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Here's
an example of what I envision:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Consider
a plate or PWB with holes near the edges. To maximize
usable area on the plate, today we optimize the holes
such that when they are at their largest size and
maximum mislocation, the edge distance is enough so
the tear out strength exceeds the design requirement.
The edge distance and material properties are enough
to overcome shear. Consider that the thickness of the
plate and the material properties also affect the tear
out strength, and these parameters also have
tolerances applied. Ignoring material properties for
now, if the plate is thicker than nominal, we could
decrease the edge distance and maintain the same tear
out strength. However, currently we do not have a
mechanism to link the thickness, hole size, and
positional tolerance for the hole. It could be a good
idea if such linkage yielded working parts with less
cost. I assume the complexity of such a situation is
not feasible for manual workflows, but for automated
workflows this seems like it could be easy.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Martin,
I foresee methods specifying tolerances that link
separate specifications, such as the thickness and the
hole size/positional tolerance. Again, today, the
thickness and hole size/location are independent
specifications. There are many examples where this
sort of linkage would yield greater allowable
variation for parts. However, since most workflows are
manual today, and most design and analysis are also
done manually, and we do not have methods for defining
these specifications yet, this opportunity remains
unfulfilled.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">***<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">The
example above is a machining/cutting example and
simple enough to get my point across. Given that
GD&T and GPS are developed for manual workflows
and communication between people in those workflows,
the ultimate result would be defining performance
parameters and your machining twin could optimize all
applicable variables to achieve interchangeable
functional parts without specifications defined for
manual workflows, such as GD&T and GPS. No
GD&T, no GPS, only performance parameters,
simulation, analysis, and twins.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span style="font-size:12.0pt">Best
Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Bryan
Fischer<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">TDP360
LLC<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Office
(503) 625-2480<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Mobile
(503) 260-3084<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> step-manufacturing
<a class="moz-txt-link-rfc2396E" href="mailto:step-manufacturing-bounces@steptools.com"><step-manufacturing-bounces@steptools.com></a>
<b>On Behalf Of </b>Martin Hardwick<br>
<b>Sent:</b> Monday, July 18, 2022 8:00 AM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:step-manufacturing@steptools.com">step-manufacturing@steptools.com</a><br>
<b>Subject:</b> [step-manufacturing] Testing digital
twin manufacturing using the AS1 assembly<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p>All,<o:p></o:p></p>
<p>We are testing digital twin manufacturing using the AS1
assembly.<o:p></o:p></p>
<p>The assembly is fastened using six nut/bolt
combinations, and each one needs to be given individual
identification as it is inserted into the assembly, so
that it can be given unique characteristics and
properties.<o:p></o:p></p>
<p>I think we all agree that at least part of this
identification should be a serial number, but we
disagree on how the serial number should be stored in
the STEP data.<o:p></o:p></p>
<ol type="1" start="1">
<li class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0
level1 lfo1">
Option 1 is to store the serial number in the id
attribute of the product entity.
<o:p></o:p></li>
<li class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0
level1 lfo1">
Option 2 is to store the serial number in the id
attribute of the product_definition entity.<o:p></o:p></li>
</ol>
<p>While somewhat arcane, the first definition keeps a
clean separation between design and manufacturing
because each of the six products has a different
existence and identification.<o:p></o:p></p>
<p>The second definition enables more data sharing between
the instances which allows for the possibility that
design and manufacturing will occur in tandem, with some
design changes occurring during the manufacturing, and
this is one of the goals of digital twin manufacturing.<o:p></o:p></p>
<pre>-- <o:p></o:p></pre>
<pre>Martin Hardwick<o:p></o:p></pre>
<pre>President STEP Tools, Inc.<o:p></o:p></pre>
<pre>Cell: 518 253-0596<o:p></o:p></pre>
<pre>"There are billions of STEP files and millions of STEP-NC files"<o:p></o:p></pre>
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</blockquote>
</div>
</blockquote>
<pre class="moz-signature" cols="72">--
Martin Hardwick
President STEP Tools, Inc.
Cell: 518 253-0596
"There are billions of STEP files and millions of STEP-NC files"</pre>
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