[step-manufacturing] Minutes of February 20th Conference Call

[Martin Hardwick]

Attendees
--------------
Martin Hardwick, STEP Tools, USA
David Loffredo, STEP Tools, USA
Mikael Hedlind, Scania, Sweden
Bob Erickson, Pratt & Whitney, USA
Vincent Marchini, Ameritech, USA
Fred Proctor, NIST, USA
David Odendahl, Boeing USA
Alain Brail Airbus (retired), France
Sid Venkatesh, Boeing, USA
Leon Xu, Boeing, USA
Magnus Lundgren, KTH, Sweden
Bengt Olsson, Sandvik, Sweden

We reviewed three business cases for the CAM vendors to implement STEP-NC.

The first case explains how STEP-NC on a CAM system can make an SME more 
competitive when bidding for new jobs.
ftp://www.steptools.com/private/CAM_exchange/Cycle_1/SME_Bidding.pdf

The second case explains how STEP-NC can help users migrate to more 
modern and functional CAM systems.
ftp://www.steptools.com/private/CAM_exchange/Cycle_1/CAM_System_Migration.pdf

The third case explains how STEP-NC enables many new shop floor 
applications for CAM systems.
ftp://www.steptools.com/private/CAM_exchange/Cycle_1/CAM_On_The_Shop_Floor.pdf

The three business cases are drafts that should not be shared until they 
have been completed by Boeing. If you have any feedback please contact 
the editor.

We reviewed the agenda for the face to face meeting. Three pilots are 
being proposed to exercise the new STEP-NC interfaces while they are 
being implemented by the vendors. The first pilot will use them to allow 
vendors to propose more complete cutting tool solutions. The second 
pilot will use them for closed loop manufacturing, The third pilot will 
use them for distributed manufacturing simulation.

http://www.steptools.com/camxc/

We reviewed an issue with the modeling of assembly constraints in AP242. 
New chain based entities are being proposed to model the connection 
between an assembly requirement and the part instance that has to meet 
that requirement. The connection can be quite complex because there may 
be many bearing seals in a drive train but the constraint only applies 
to one of the seals, on one of the bearings, on one of the wheels.

The current proposal is to model the connection with new path entities 
that begin with the name "chain_based". So far three have been proposed. 
Each path entity visits each sub-assembly between the constraining 
assembly and the constrained part. The good thing about them is that 
they put all the path data into one entity where it is easy for an 
implementer to find. The bad thing is that they contradict twenty years 
of careful modeling to avoid insertion and deletion anomalies.

ftp://www.steptools.com/private/CAM_exchange/Cycle_1/chained_multi-level_vs_higer-lower_level_entities.pdf

One motivation for the inclusion of the chain entities may be the 
difficulty of modeling constraints that span multiple files. The new 
chain entities can be more easily extended to include the name of each 
file that contains the next item in a chain. Updating all of the 
entities currently included in STEP to model assemblies would be much 
more difficult.

However, the success of the recent ballot on Edition 3 of Part 21 
removes this constraint because it allows any two entity instances to be 
linked by URL's. Therefore, all the assembly modeling entities in STEP 
can now reference entities in external files and the new chain based 
entities should no longer be necessary.

KTH has tested the implementation of the chains using the traditional 
STEP entities and found them to have all the required functionality and 
to be just as easy to implement.

The next conference call will be held at the new regular times on 
Wednesday March 6th. A recording of this conference call is available at 
the following ftp site:

ftp://www.steptools.com/private/CAM_exchange/Cycle_1/stepmanuf_telecon_20130220.wmv

Martin Hardwick
Team Leader ISO STEP-Manufacturing

Action Items
-----------------
1. David Odendahl to complete the three business cases.
2. Fred Proctor to test the new STEP-NC export for Mastercam.
3. All to review participation in the pilots.