[step-manufacturing] Testing digital twin manufacturing using the AS1 assembly

[Bryan Fischer]

Hi Martin, All

I don’t really care which method is used in STEP as long as it works with the rest of the design / manufacturing / quality / etc. space. I do care that we enable broader application and extend our ability to simulate more of the product (via twin or whatever you prefer to call it).

Your description of the benefits of option 2 are intriguing. I’ve had an idea for some time that I haven’t created a way to do it. I propose that specifications, specifically tolerances, could and should be linked. We do that today in very simple cases with MMC (MMR) and LMC (LMR) modifiers – one interpretation of these specifications is that the size of the geometric tolerance zone depends on the size of the feature of size; for example, the larger the hole, the larger the location tolerance. This is already addressed in 242.

Here's an example of what I envision:
Consider a plate or PWB with holes near the edges. To maximize usable area on the plate, today we optimize the holes such that when they are at their largest size and maximum mislocation, the edge distance is enough so the tear out strength exceeds the design requirement. The edge distance and material properties are enough to overcome shear. Consider that the thickness of the plate and the material properties also affect the tear out strength, and these parameters also have tolerances applied. Ignoring material properties for now, if the plate is thicker than nominal, we could decrease the edge distance and maintain the same tear out strength. However, currently we do not have a mechanism to link the thickness, hole size, and positional tolerance for the hole. It could be a good idea if such linkage yielded working parts with less cost. I assume the complexity of such a situation is not feasible for manual workflows, but for automated workflows this seems like it could be easy.

Martin, I foresee methods specifying tolerances that link separate specifications, such as the thickness and the hole size/positional tolerance. Again, today, the thickness and hole size/location are independent specifications. There are many examples where this sort of linkage would yield greater allowable variation for parts. However, since most workflows are manual today, and most design and analysis are also done manually, and we do not have methods for defining these specifications yet, this opportunity remains unfulfilled.

***

The example above is a machining/cutting example and simple enough to get my point across. Given that GD&T and GPS are developed for manual workflows and communication between people in those workflows, the ultimate result would be defining performance parameters and your machining twin could optimize all applicable variables to achieve interchangeable functional parts without specifications defined for manual workflows, such as GD&T and GPS. No GD&T, no GPS, only performance parameters, simulation, analysis, and twins.

Best Regards,

Bryan Fischer

TDP360 LLC
Office   (503) 625-2480
Mobile  (503) 260-3084

From: step-manufacturing <step-manufacturing-bounces at steptools.com> On Behalf Of Martin Hardwick
Sent: Monday, July 18, 2022 8:00 AM
To: step-manufacturing at steptools.com
Subject: [step-manufacturing] Testing digital twin manufacturing using the AS1 assembly


All,

We are testing digital twin manufacturing using the AS1 assembly.

The assembly is fastened using six nut/bolt combinations, and each one needs to be given individual identification as it is inserted into the assembly, so that it can be given unique characteristics and properties.

I think we all agree that at least part of this identification should be a serial number, but we disagree on how the serial number should be stored in the STEP data.

  1.  Option 1 is to store the serial number in the id attribute of the product entity.
  2.  Option 2 is to store the serial number in the id attribute of the product_definition entity.

While somewhat arcane, the first definition keeps a clean separation between design and manufacturing because each of the six products has a different existence and identification.

The second definition enables more data sharing between the instances which allows for the possibility that design and manufacturing will occur in tandem, with some design changes occurring during the manufacturing, and this is one of the goals of digital twin manufacturing.

--

Martin Hardwick

President STEP Tools, Inc.

Cell: 518 253-0596

"There are billions of STEP files and millions of STEP-NC files"
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