A digital twin matches the state of a part as it exists at any moment in time, which offers the unique new capability to measure the result while the part is still being machined.
The twin is created by combining readily available STEP models for part, tooling, and semantic tolerances, live machine feedback using MTConnect, and a new machining simulator. The twin can be enhanced with additional authoritative information from machine sensors, tool pre-setters, probes, or any other available source.
The twin contains all of the information needed for immediate analysis and measurement by metrology tools — while the part is still on the machine tool.
The digital thread server can provide a 3D model of the live simulation results to metrology tools running as a web service, on the desktop, or shop floor. The When on-machine probing is used, the server can also provide QIF descriptions of the measurement and affected tolerances to metrology software.
The latest version of STEP, AP242, includes semantic tolerances, which are computer-interpretable descriptions of allowable variations connected to faces on the part shape. There may also be presentation tolerances, which are human-interpretable drawings of traditional blueprint annotations.
MTConnect is an extensible XML format for streaming machine tool speed, feed, tool tip location, and other state, all with time stamps. It is supported by many vendors — Okuma, Mazak, DMG, Haas (Mnet), Kuka (Kuka Connect), Mitutoyo, and others.
QIF (Quality Information Framework) is an XML format for describing measurement results and exchanging them between tools.