Inspection Models

[kennebec]

Greetings Forum

Inspection would like to start offline and proactive programming up comming inspections,(as it is now machines can be down waaaaaay to long on complex inspections)Programming has been asked to provide them with data, for a finished part I can simply output the Model we use to the format requested, the problem arises when incorporating multiple processes to "inprocess conditions" as it is now I simply leave material X and Z for the next operations, apparently it is not that simple in QC, so aside from making inprocess models do any of you do this or have any suggestions?

Thanks Forum

[robk]

I'm not sure how your company works, but we make programs to prints not models. We get the models from customers, but I check every single dimension to make sure the model matches the print (the print I'm checking now has 21 pages). The parts I program are pretty complex, very large, and very expensive. There is no way that I am giving my in-process-workpiece to QC. I don't want to be responsible for handing over a model that may have issues. I leave that to the process planner/engineer. IMO, QC should also be checking the parts to B/P and not the model unless your procedures allow that.

[Pilot Plant Supervisor]

Can you verify and save as an STL? QC should be able to program off the STL file for in-process.

[kennebec]

Thanks guys for the info...

Pilot Plant, yes I can save as STL but QC is not real satisfied with that they would prefer In Process Iges Models as the discussion continues.

[Brad St.]

What kind of tolerances are you looking to hold? If you start talking file conversions such as iges you could very easily lose tenths in translation alone on the models.

 

Inspecting to models is the way to go for complex parts but the data MUST be correlated back to QC requirements (ideally GD&T) called out on the prints or inspection criteria. Your quality process must be robust enough to ensure this can be done well enough to get the data you need.

 

I don't see why your QC would not be able to use say a setup sheet that would list the "Stock conditions" for a feature to add into their tolerance zone. The programming could be done offline and sent to them via electronic format (pdf, xls, html). Labeling and identifying features is what would become an important part so data is correlated nicely.

 

Two lists could maybe be generated or one using X+ setup sheets labeling and identifying this information.

[Brad St.]

oops double post sorry.

[taperlength]

I do both machining center programming and cmm programming. An easy way to do inprocess is to measure to the finish model using just surface profile measurements--not dimensions. The error should be the amount of stock left on the features.

s

[Matthew Hajicek - Singularity]

One approach I've done on the most expensive and complicated projects is to model the in-process states of the part before I even start programming. I'll do an assembly in SW with each in-process state overlaid so you can turn each one off in turn and go through the whole process. Then instead of programming to the finished part model I program to the in process model, and inspect to it too. Consider each operation as a separate job with a before-machining and an after-machining model.

 

This approach also allowed me to build in mounting features to, and design fixturing for the intermediate states of the part. I set the tolerances for roughed features and mounting features and we did a full inspection at each stage.