[step-manufacturing] Minutes of conference call #13

[Martin Hardwick]

_Attendees_
Martin Hardwick, STEP Tools, USA
David Loffredo, STEP Tools, USA
Fred Proctor, NIST, USA
Leon Xu, Boeing, USA
Mikael Hedlind, KTH, Sweden
Magnus Lundgren, KTH, Sweden
Chris Pfeifer CCAT, USA
Fiona Zhao, NIST,/New Zealand
Larry Maggiano, Mitutoyo, USA
Bob Erickson, Pratt & Whitney, USA
Sid Venkatesh, Boeing, USA
David Odendahl, Boeing, USA
Anna Valente, ITIA-CNR, Italy

_Apologies for Absence_
Aydin Nassehi, U.Bath, UK
Stephen Newman, U.Bath, UK
Alain Brail, AlBavis,  France
Ian Stroud, Switzerland
Bengt Olsson, Sandvik, Sweden

We reviewed the results of the dry run testing at NIST.

ftp://ftp.steptools.com/private/NIST/NIST_boxy-setups.ppt

Some concern was expressed by a third party on the desirability of 
placing the part at the edge of the fixture instead of the center 
because this will result in an uneven distribution of forces.

KTH explained that this fixturing method was chosen for simplicity and  
to reduce the number of setups. The T square is only necessary for the 
third setup when a surface that has yet to be machined is at the bottom 
of the part. In the other setups the square is used a a quick method to 
position the part and it can be replaced by a probe or other measuring 
device.

ftp://ftp.steptools.com/private/NIST/8_Setup_Fixture_Assembly.pdf

We discussed the required attributes of the tool. It was observed that 
the tooling data in V7 of Boxy is unfinished because the number of 
flutes is not set, and that the information is incomplete because it 
does not include a "stick out" (gauge)  length, a flute (cutting) 
length, and a shank diameter. For Boxy the shank diameter must be less 
than the flute diameter to avoid rubbing the shank during machining. 
Several diagrams were made showing the required tool attributes and 
these have been put into the following ftp directory:

ftp://ftp.steptools.com/private/NIST/tools/

We would like to add the missing information by importing ISO 13399 
files into the STEP-NC Explorer. We would also like to create better 
geometry models for the tools showing the reduced shank dimensions and 
other key attributes. We would like for presentation information to be 
included with the geometry models because many slightly different terms 
are used to describe these parameters by industry. We would like to use 
the standard terms defined by ISO 13399 and then show where those terms 
apply on the geometry models to avoid any ambiguity.

We reviewed the information model developed by Fiona Zhao for her Ph.D 
thesis at the University of Auckland which she recently completed 
(congratulations to Dr. Zhao). The  model is an extension of the HiPP 
model developed by Tom Kramer at NIST. HiPP is an extension of STEP-NC 
for High level inspection Process Planning. Fiona implemented much of 
this model while testing her thesis and we would like to use her results 
where applicable in Edtiion 2 of AP-238.

ftp://ftp.steptools.com/private/NIST/HiPP_cover_letter.doc

The model adds an its_tolerances attribute to manufacturing features. 
There were questions about the value of this attribute because as was 
shown during the Scania demonstration the tolerances that apply to a 
feature can be deduced from the STEP geometry.

http://www.steptools.com/library/stepnc/2008_sweden/closedloop/index.html

However, Fiona's model also includes attributes for required machine 
accuracy so that an end user can determine if the tolerance needs to be 
measured during machining. If the machine is above the required upper 
level of accuracy then no measurement is necessary. If the machine is 
below the required minimum level of accuracy then the part cannot be 
made on this machine and again no measurement is necessary. If the 
machine is between the upper and lower levels then a dm_workingstep (dm 
= dimensional measurement) is created to make the necessary measurements 
and confirm or deny the satisfaction of the tolerance. (We might want to 
make the dm_workingstep a dm_workplan so that there can  be a setup and 
alternate measurement plans for different types of equipment).

It was suggested that the its_tolerances attribute of the model might be 
renamed its_critical_tolerances because these are the ones that must be 
met for machining to continue. It was further suggested that the 
accuracy upper and lower requirements might be defined for each critical 
tolerance to allow for finer grain decision making.

Questions were also asked about the dm_features in the model. These 
featured describe lines, planes, cylinders and other geometric items 
that are already in the geometry model. In her thesis work Fiona 
measured the underlying geometry in the geometry models and did not use 
these features.

The HiPP model will be further discussed at the NIST meeting.

Martin Hardwick briefly showed that the STEP-NC Explorer now supports 
http addresses. We will revisit the use of STRL links for navigation 
between program models in the next conference call.

The next call will be at the regular times on Wednesday April 28. No 
video was made of this call because of an error by the team leader.

Martin Hardwick
Team Leader STEP-Manufacturing

Action Items
----------------
Sandvik to make ISO 13399 models for the cutting tools.
Boeing to make AP-203 e2 presentation models for the cutting tools.
STEP Tools to integrate the ISO 13399 and AP-203 e2 models into the 
AP-238 for Boxy.
NIST, Boeing and CCAT to machine Boxy in Wax.
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