[step-manufacturing] Fwd: Scenario writeup for Boeing demo

[Martin Hardwick]

Hi Martin,
Here is my stab at a scenario for the Boeing/Renton demo in October.
Goal: demonstrate the integration of portable-arm metrology with 
machining for validation of in-process features and final part machining 
using STEP-NC.
This demo picks up where the NIST Boxy demo left off. The NIST demo 
showed how STEP-NC can be used to represent the information needed to 
sequence through multiple setups. Each setup produces some in-process 
geometry that has the potential to be validated with an external 
measurement system with better accuracy than the machine tool. This 
external system can drive go/no-go decisions for validation, and also 
help with part registration between setups. However, it is recognized 
that part registration is not a primary function of portable-arm 
metrology given the mature state of on-machine probing systems for this 
purpose such as those from Renishaw.
1. The blank boxy stock is fixtured at the nominal first setup position, 
and the three orthogonal datum surfaces are machined as in the NIST 
demo. The part is flipped to its second setup using the machine stops 
and vise for registration.
2. The features at the second setup are machined. The Faro arm operator 
will asked to conduct two manual inspection operations, one for the 
flatness of the top surface and another for the pocket. STEP-NC 
integration here means that the Faro arm software has imported the 
AP-238 file, recognized the measurement steps, built a list of these 
steps, and can guide or follow the operator as he sequences through the 
measurement operations. For example, the operator could indicate that he 
is measuring the flatness of Datum B, picks some number of points, 
signals that he is done, the Faro software determines the flatness and a 
go/no-go decision can be made. Likewise for the pocket measurement.
3. The operator flips the part into setup 3. Here we have three choices 
on how to proceed. One choice is to rely on machine stops and vise 
geometry to ensure that the datum surfaces from setups 1 and 2 are 
positioned properly, as was done in the NIST demo. A second choice is to 
use these stops, but get a better registration through the use of 
on-machine probing with the Renishaw system. A third choice is to use 
the Faro arm to get the registration. The third choice does the most 
flexing of STEP-NC data exchange: the measurement operation needs to be 
recognized by the Faro software, and its results (full 6-DOF transform) 
need to be fed back into STEP-NC machine or the CNC's TRAORI table.
4. Machining continues at the third setup. The Faro does the same 
feature validations as in (2) for this setup.
5. Part flipping continues through all the remaining setups, with 
pre-machining registration via any of the three choices described above, 
and post-machining validation via the Faro. We could try all three 
choices to show the range of functionality supported by STEP-NC.
6. At the seventh setup, the Faro can be used to measure the top and two 
sides of the part, if reachable, for a final validation.
Faro Inc. would need to develop STEP-NC import to the extent that they 
can sift out the measurement working steps, present them to the operator 
and generate measurement results that can be fed back into STEP-NC 
machine via an export facility.
Can you send this out to the group and see what they think?
--Fred
Frederick M. Proctor
Group Leader, Control Systems Group
National Institute of Standards and Technology
100 Bureau Drive, Stop 8230
Gaithersburg, MD 20899-8230
301-975-3425 (voice)
301-990-9688 (fax)
240-479-6043 (mobile)
frederick.proctor at nist.gov (email)
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