When creating Product Manufacturing Information (PMI) for industry standards, designers and engineers benefit from being able to add annotations on their 3D models. Thanks to SOLIDWORKS MBD, they can annotate and organize 3D data such as dimensions, tolerances, surface finishes, notes and Bill of Materials (BOM). This application helps in the automation of manufacturing processes such as tolerance analysis, machining and inspection. In this article, we will provide different examples through which the use of MBD was critical to creating designs for the military, compliant with the new MIL-STD-31000 A+B standard.

Using CAM

CAM products read CAD files to generate a Numerical Control (NC) Code. This is incredibly beneficial to a manufacturing environment, but some details, tolerances or surface finishes are generally only shown in 2D drawings. CAM software is unable to read 2D drawings, so operators often must do additional machine programming to ensure that no details have been missed. SOLIDWORKS MBD is a solution that drives certain applications automatically, including CAM, by presenting the design information clearly.

For example, both images below convey the same information. Which is easier to comprehend?

Figure 1: 2D SOLIDWORKS Drawing

Figure 2: Part annotated with SOLIDWORKS MBD 

The document Figure 2, annotated with MBD, is clearer, less cluttered and still contains all the necessary information for fabrication. SOLIDWORKS MBD itself is a way to define and organize dimensions and tolerances and publish them to formats such as eDrawings, STEP242 and 3D PDF.

Using MBD With Standards

You may begin to hear about MBD more and more, especially if your company works with the Department of Defense (DoD). This is due to the semi-recent implementation of MIL-STD-31000 A+B. The overall standard is MiL-STD-31000, with A and B each being respective appendices. Appendix A and B provide details and suggestions about Technical Data Package (TPD) elements, as well as specific steps required for the MBD process.

Figure 3: TDP Relationships from Appendix A

Design Stages of the MIL-STD-31000 A+B.

A simple explanation of the new standard is that the military wants to move its design processes into the 21st Century. Part of that is going paperless, but the main point of the new standard is to change the way that levels of detail are demarcated in the design process. The old standard, MIL-DTL-31000, used numeric levels 1, 2, 3 to describe ascending levels of detail, where level 3 would fully define a product. The new standard changes these to three distinct stages.

• Conceptual: Consisting of TDP elements necessary to define design concepts, including appropriate information for analysis.

Figure 4: Conceptual Design Stage [Appendix A Section B5]

• Developmental: Contains TDP elements needed to provide data to support the analysis of a specific design approach, prototype fabrication, and limited production.

Figure 5: Developmental Design Stage [Appendix A Section B5]

• Production: Product level TDP requires all the elements necessary to provide the design, performance requirements, engineering, manufacturing, inspection, production and quality assurance information needed to fully define the item and manufacture of the product.

Figure 6: Production Design Stage [Appendix A Section B5]

These new levels include new requirements for presenting and analyzing the data at each stage of the design process. This is where MBD comes in. If a 3D model is used in a product level TDP, sharing the designs must include all the necessary information to properly define the project. This includes dimensions, tolerances, materials and other information needed to fully convey design intent. In short, under the new standard using unannotated and undefined features will no longer be allowed. Section 5.3.2.3 states, “While this standard is specific to work done with the US Military, it should not dissuade any engineer looking for a more modern, clear and concise way to communicate technical information away from working with MBD.”

Model-based definition brings the same advantages of 3D design to manufacturing, significantly saving both time and money. By now, the question should have changed from “How does MBD fit into my design workflow?” to “How can I design without it?”.

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