MBD

What is MBD?

MBD, or Model-Based Definition, refers to an approach where the 3D model serves as the only and primary definition of the product. In the context of the machine shop, machining facility, and for the machinist on the shop floor, this means all the information needed for manufacturing and inspection is embedded directly in the 3D model—no need for separate 2D drawings.

With MBD, the 3D model isn’t just a geometric representation; it also includes the product’s dimensions, tolerances, geometric tolerances (GD&T), materials, surface finishes, and other essential specifications relevant to machining. The model serves as a “single source of truth” for the entire manufacturing industry chain.

MBD in Machine Shops and Machining Facilities

In the shop environment, MBD changes how information is read and used. Traditionally, machinists have interpreted dimensions and tolerances from 2D drawings, but in an MBD workflow, this information is read directly from the 3D model. This reduces interpretation errors and improves machining quality, especially with complex parts and tight tolerances.

In machining facilities, MBD directly supports CNC machining, as many CAM systems can read PMI information attached to 3D models. This allows CAM programming, CNC machining, and measurement to be more tightly connected within the same digital workflow.

MBD and PMI as Part of the 3D Model

MBD relies heavily on PMI data (Product and Manufacturing Information), which is attached directly to the surfaces and features of the 3D model. PMI includes, for example, dimensions, tolerances, surface roughness requirements, and material specifications.

For machinists, this means a clearer overall picture: all necessary information is found in the same 3D model without having to cross-reference multiple documents. This also simplifies CMM measurement and quality assurance in the machine shop.

Benefits of MBD in the Manufacturing Industry

Within the manufacturing industry, MBD offers significant benefits in both efficiency and quality. As the need for 2D drawings diminishes, managing documentation becomes simpler. The digital model flows seamlessly from design to machining, measurement, and on to subcontractors.

MBD reduces errors, speeds up change management, and supports automation, as well as Industry 4.0 initiatives. Especially in complex CNC machining and precision machining, MBD improves production predictability and reduces waste.

MBD and Standards

MBD is governed by international standards like ASME Y14.41 and ISO 16792, which define how dimensions, tolerances, and other data should be represented within the 3D model. These standards ensure that 3D models are consistent and interpretable across different CAD, CAM, and measurement systems.

In machine shops, adherence to these standards makes collaboration between customers, subcontractors, and different machining facilities much easier.

Summary

MBD, or Model-Based Definition, is a modern way to define machinable parts and assemblies directly through a 3D model. For machine shops and machining facilities, MBD means clearer communication, fewer errors, and more efficient CNC machining. When all critical manufacturing information is housed within one digital model, the entire process in the manufacturing industry becomes faster and of higher quality.