STEP-NC Machining Accuracy Demonstration, Stockholm, June 14, 2012

On June 14, 2012, the STEP Manufacturing team (ISO TC184 SC4 WG3 T24) met at the KTH production engineering labs in Stockholm, Sweden for an Industry Day and demonstration of machine tool accuracy calculation. This was part of a week-long T24 meeting as part of the larger ISO TC184 SC4 group in Stockholm.

The demonstration milled a forged blank for a Crown Wheel Gear on an older Mazak VQC 20. Prior to the demo, the Mazak was measured using laser and a loaded double ball bar. Next, ASME B59.2 software developed by NIST used this information to predict the positional accuracy of the actual tool movements. Finally Cross-section based force calculation software developed by Boeing used cross section information in the STEP-NC machining data to predict the deflection of the cutting tool under load.

These components were combined to predict the machining result, and when the machined article was measured, the shape of the predicted deflection correlated with the observed deflection, but the magnitude of the predicted deflection was larger than what was observed. A second machining test is being planned to repeat the experiment at another facility.

We also discussed STEP kinematics models for machine tools, and showed a model of the tool changer on the Mazak. We had extensive discussions on external reference between STEP files, including cutting tool models built from files on vendor websites, and agreed on the scope and form of a Part 21 extension to simplify references.

Browse the minutes of the meeting for a complete list of all discussions.

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