[step-manufacturing] Minutes of tenth conference call

[Martin Hardwick]

Attendees
---------------
Martin Hardwick, STEP Tools
Mikael Hedlind, KTH
Magnus Lundgren, KTH
Bengt Olsson, Sandvik
David Odendahl, Boeing
Alain Brail, AlBavis
Fred Proctor, NIST
Leon Xu, Boeing
Patrick Marchand, CEITM
Larry Maggiano, Mitutoyo
Eric Tingle, Mitutoyo
Ian Stroud, EPFL
David Loffredo, STEP Tools
Bob Erickson, Pratt & Whitney


Apologies for absence
--------------------------------
Gary Hargreaves, Mastercam
Xun Xu, University of Auckland
Sid Venkatesh, Boeing
Aydin Nassehi, University of Bath
Matthew Lloyd, CCAT

Boeing plans to machine the test part this week. They will make both 
five axis and three axis versions on three different machines. The 
other machining participants will be KTH and CCAT. Participation by 
the University of Bath and NIST has yet to be confirmed.

We discussed the meeting invitation and registration form. The 
registration form was extended to ask about dietary restrictions 
(vegetarian etc) and to include check boxes for those who would like 
to share a ride to Mitutoyo and/or the SC4 meeting. Both forms have 
been posted to the home page of the STEP Tools web site. Due to the 
uncertainties of the recession, the hosts would very much appreciate 
it if you can register early.

We will assume that the nationality restrictions that applied to the 
CCAT meeting will also apply to the Renton meeting, but for early 
registrations we may be able to relax the rules.

We reviewed the changes made to the technical corrigendum since the 
Hartford meeting. Additions have been made to define a toolpath 
transformation for workplans, to define a tool reference direction 
for non-spinning tools, to define a tool gage placement and tool end 
point placement, and to allow executables to be enabled or disabled.

ftp://ftp.steptools.com/private/Vancouver/meeting/stepnc_tc1_overview_20090227.ppt
ftp://ftp.steptools.com/private/Vancouver/meeting/stepnc_tc1_20090227.pdf

The toolpath transformation for workplans was motivated by the 
experiences gained from the impeller machining in the Hartford 
demonstration. In this demonstration the same tool paths were 
machined 8 times for the eight blades. Considerable flexibility and 
data compression was gained by allowing one workingstep to be 
repeated 8 times with different toolpath orientations. This extension 
makes the same reuse possible for workplans.

The tool reference direction extension was motivated by experience in 
using STEP-NC to control a tape laying machine. The tow head on these 
machines can be modeled as a tool but it does not spin, and both its 
axis and its direction needs to be controlled. The extension makes 
this possible by adding a tool reference direction property to cutter 
location and cutter contact tool paths.

The tool gage placement and tool end point allow the gage line and 
tool path reference point to be defined for a tool. At the moment, 
AP-238 assumes that the tool end point is at the origin of the tool, 
and ISO 13399 assumes that the tool gage point is at the origin. The 
new placements allow both conventions to be used and allow product 
models that use other conventions to also be used to define tools. 
ISO 13399 has a similar concept.

The executable enable/disable flag was motivated by experience with 
the Hartford and Sandvik demonstrations. In the Hartford 
demonstration it became desirable to select a subset of the blades 
for machining. For each operation it was determined which paths had 
to be executed to complete the blade and this execution order was 
captured by setting flags on the workingsteps. The new flag will 
allow this execution order to be shared with other users by 
exchanging a data file. In the Sandvik demonstration a selective was 
used to capture different machining plans for different users (large 
size tool, regular size tool and HSM). The end user was required to 
delete the undesired options before machining began. The new flag 
will allow an end user to resolve the ambiguity without deleting data.

We also discussed three open items: the parameters for plunge 
milling, the curve probing operation and clarifications to the 
semantics of workpieces and rawpieces.

The parameters for plunge milling have been tested by Leon Xu, 
outside of the STEP-NC context, since the Hartford demonstration. 
They should be tested in a STEP-NC test file and then included in the TC.

The curve probing operation was further refined during the conference 
call in discussion with Mitutoyo. In order to use the curve probing 
entity with cutter location paths as well as cutter contact paths 
there needs to be an optional parameter to define the surface normal 
at the contact point. This was added to the definition and the name 
of the curve_axis parameter was changed to probe_axis to make its 
meaning clearer. More testing will be done at the May demonstration.

Clarifications to the semantics of workpieces and rawpieces are 
desirable because the current definition is not very strict. We would 
like to propose that the rawpiece of a workpiece should be the state 
of that workpiece at the start of the main workplan and not some 
intermediate state. We would also like to propose that the list of 
workpieces given in the project definition should be the list of 
pieces made by the project (the final deliverables). Finally a 
scoping rule has been defined for the as-is, to-be, removal and 
fixture workpieces that can be defined for every executable that uses 
the most locally defined workpiece first and then defaults to those 
defined by the owning workplans until the main workplan is reached.

These rules were determined in cooperation with KTH in the context of 
a project to model machining operations for the automotive industry, 
but they are quite complex so team members are asked to review them 
for compatibility with their industries before the Renton meeting.

The Goto meeting video for the conference call is at:
ftp://ftp.steptools.com/private/Vancouver/stepmanuf_telecon_20090304.wmv

The next conference call will be held on Wednesday March 18th at NOT 
the usual times because the US has moved to summer time. Given that 
the call is towards the end of the day for Europe we will make it one 
hour earlier than usual for Europe and at the same time for the US.

Action items
------------------
1.   David Odendahl to machine the test part to make sure that the 
male and female halves fit.
2.   NIST and U. Bath to confirm participation.