PMI

Product and Manufacturing Information: tolerances, datums and other manufacturing requirements attached to a 3D model as structured data, not only as text on a drawing.

Definition

What is PMI?

Product and Manufacturing Information, PMI, is the set of manufacturing-relevant requirements attached to a 3D model: dimensions, tolerances, datums, surface finish, material notes and similar callouts. PMI is what turns a purely geometric shape into a fuller product definition that also states how the part is allowed to vary and what it needs to achieve.

PMI can be attached to a model in two meaningfully different ways. Visual PMI is a callout that displays correctly on screen but exists as a picture, similar to text on a drawing: a person can read it, but software cannot reliably act on it without that person re-entering it as data. Semantic PMI is structured, model-linked data: a tolerance value tied directly to the specific face, edge or feature it controls, so software can query it directly.1

How PMI reaches a manufacturer

STEP AP242 is the current application protocol built to carry semantic PMI alongside geometry in a single exchangeable file.1 Whether a specific file actually uses that capability depends on the authoring CAD system and how the model was built and exported. In many real exchanges today, PMI still arrives separately, as a 2D PDF drawing alongside a geometry-only 3D file, rather than as semantic data inside the model.

NIST's applied research on standards-based interoperability has focused directly on this handoff: keeping a model-based product definition, PMI included, usable through manufacturing and inspection rather than losing meaning along the way.2 More recent NIST work looks specifically at migrating existing PMI models toward a more consistent, reusable structure.3

Why the distinction matters for manufacturing reasoning

A manufacturability or cost assessment needs to know not just that a hole exists, but what it requires: its tolerance, its relationship to a datum, whether a secondary operation is implied. When that information exists only as visual PMI or as text on a drawing, software cannot use it directly, and linking each requirement back to the right geometric element becomes a task in itself. Semantic PMI is what removes that translation step, when it is actually present in the file.

Frequently asked questions

Is PMI the same as GD&T?

GD&T is the symbolic language used to express many kinds of PMI, such as tolerances and datums; PMI is the broader category of manufacturing-relevant model data, which also includes things like surface finish and material notes.

Does every 3D model have PMI?

No. A model can be pure geometry with no PMI at all, in which case tolerances and other requirements typically live on a separate 2D drawing instead.

Why does it matter whether PMI is semantic or just visual?

Semantic PMI is structured data a computer can read directly; visual-only PMI is a picture a person has to interpret and re-enter.

Notes & references

  1. International Organization for Standardization (2025). ISO 10303-242:2025, Industrial automation systems and integration — Product data representation and exchange — Part 242: Application protocol: Managed model-based 3D engineering (Edition 4). ISO. https://www.iso.org/standard/84300.html Specifies how semantic PMI is represented and carried within STEP AP242.
  2. Fischer, K., Rosche, P., Trainer, A., Barnard Feeney, A. & Hedberg, T. (2015). Investigating the Impact of Standards-Based Interoperability for Design to Manufacturing and Quality in the Supply Chain. NIST GCR 15-1009. https://doi.org/10.6028/NIST.GCR.15-1009 NIST-funded research on keeping a model-based product definition, including PMI, usable through manufacturing and inspection.
  3. Barnard Feeney, A. & Thurman, T. (2023). On Migrating ISO 10303 PMI Models to a Common Core. NIST AMS 100-51. https://doi.org/10.6028/NIST.AMS.100-51 Addresses practical migration of existing PMI models toward a common, reusable core.