MBD grew out of the need for aerospace and automotive OEMs to capture and send data about parts and assemblies that went beyond what CAD could deliver. As part of that research, Manufacturing Engineering had a long and illuminating conversation with David Olson director of sales and marketing for Verisurf, Inc. Anaheim, Calif.
Manufacturing Engineering: What would you like to say to small and medium-sized enterprises, the smaller guys, the 20-person shop to the 200-person shop? What do you think they need to know about Model-Based Definition?
David Olson: Manufacturers need to know the many benefits of embedded MBD and related product manufacturing information, or PMI, for downstream applications. Model based definition is used to:
- One, eliminate or reduce assembly issues before parts are made through tolerance analysis and simulation of assemblies before they are built. This is the benefit to the OEM, and,
- Two, model-based definition and model-associated GD&T in particular is used to select appropriate CNC machine tooling and programming strategy.
- Three, model-based definition and model-associated GD&T in particular is used to select an appropriate inspection strategy for first article and production inspection.
Also, I think they need to know how to get this MBD data into their manufacturing system and leverage it through the part of manufacturing they perform. We’re skilled at helping manufacturers implement MBD because our product allows people to either import it completely or take the parts of it that are in the drawing and apply it to the 3D model.
The OEM does step one, which is simulation of the assembly. The OEM ensures if parts will go together when they are delivered to a supplier. They do this by simulating the GD&T, the maximums and minimums, and tolerance analysis. If one part is at maximum, another one is at minimum, will they still go together?
ME: Simulation information is used to refine the GD&T and then included in the MBD data for the part. Is this available to the supplier shop if they have the software and process to both read it and use it?
Yes, so, a second step is that [MBD capable] shops are using model-based associated GD&T to select their machine, their tools, and their tool paths. Once they now have a part, the third step is to use model-based GD&T to automate and accelerate the first article inspection and production inspection, whether it be on a portable or a manual or a programable CMM. In fact, if they know the model topology, if they have the CAD model and all the GD&T information, couldn’t a software automatically generate an inspection plan? The answer, of course, is yes and Verisurf is working toward that goal.
This third step is vital to getting an efficient First Article Inspection. This fourth step, FAI, is the money payoff. Nobody gets paid until the OEM signs off on the First Article Inspection.
ME: It must then be fundamentally important that the GD&T is correct when it is shipped as part of the MBD package?
Olson: That’s a very good question. In fact, the OEM is responsible typically for making sure the GD&T is applied appropriately in particular so the parts go together and function as designed. So, if the GD&T is not applied properly and there is some conflict in it, the supplier/manufacturer will typically tell them.
There are three or four companies specializing in GD&T tolerance simulation.
ME: Would MBD in any way affect reporting of metrology data for use by manufacturers?
Olson: Yes absolutely. The final step is reporting the part quality to shop management and to the OEM tiers in near real time. If all the part and assembly data is digitized, companies can display quality data as it’s being measured and if the part is trending out or in tolerance. They can report it in near real time with reference to the GD&T.
ME: Final words?
Olson: It’s amazing how many shops are still using drawings. We have a lot of customers that are still using paper drawings and IGES files.
To help these shops automate we partnered with some companies that extract GD&T from drawings and create inspection plans. This is important because suppliers, are responsible for creating AS9102 FAI, or PPAP reports for their customers which are required documents in the supply chain.
Verisurf has software that can take that associates inspection plans and associates them to our CMM measurement plan. When the measurements are completed our software populates the AS9102 Form 3. Or if they’re in automotive, their PPAP. Whether the PMI is associated to the CAD model, or whether it’s referenced on a PDF or paper drawing with an IGES file, Verisurf automates the process.
Automating the entire FAI process is important because suppliers don’t make any money until the source inspector approves the FAI report and part. Up to this point the supplier, often a small to medium machine shop, has invested a lot of non-recurring manufacturing engineering into the first article and desperately wants to get authorization to start manufacturing, make production parts and get paid. It can get pretty tense when the source inspector, quality engineer and shop owner are reviewing the first article. Verisurf wants this to be a time for production authorization celebration for the shop owner.
I believe that the use of MBD and PMI is like a train coming, driven by Aerospace and Automotive, and Biomedical OEMs with mission critical products. More people are demanding 100 percent inspection, knowing they can demand it if suppliers automate their inspection processes.
Leveraging open standard file formats is important and I would like to say, once again, to your readers, all manufacturers from the biggest OEM to the tier 4 machine shop, push your CAD vendor to output high quality STEP AP 242 files as soon as possible to automate manufacturing. The results will be higher quality parts and products, faster and less expensive across the entire supply chain.
Note to Readers: If you would like to discuss or comment on this topic, feel free to contact Bruce Morey at firstname.lastname@example.org. Mr.Morey researched and wrote an article on the importance of Model-Based Definition (MBD) for small and medium sized manufacturers. The article will be included in the December edition of Manufacturing Engineering magazine.