I’ve been sitting in on meetings of the OMAC machine tool working group for a lot of years. It looks like things are starting to come together. Here’s some news from OMAC chairman Sid Vanketesh.

Achieving data interoperability that can drive a more efficient and flexible manufacturing supply chain is the the goal of this summit.

Sid Venkatesh, chairman of The Organization for Machine Automation & Control (OMAC, www.omac.org) and associate technical fellow at The Boeing Co. has announced the Computer Aided Manufacturing (CAM) Summit that will be held Thursday, September 13th, 1:30PM to 3:30PM, Room N136 at McCormick Place in Chicago during the IMTS trade show.

“We want to make our supply chains more efficient and flexible using a neutral data standard,” noted Venkatesh. “Transferring work to suppliers is difficult when we only have 2D drawings. The drawings have to be converted into 3D models, and processes have to be developed in order to manufacture and assemble the part. Even if the 3D models are already available, the requirement to develop processes still exists, because CAD models do not contain manufacturing process information.”

The goal is a neutral standard for our process data with the following characteristics and capabilities:

Capability of representing part and assembly geometry with an acceptable fidelity
Capability of clearly defining machining and assembly processes and requirements
Availability to designers and manufacturers either directly through CAD/CAM and manufacturing systems, or through third party suppliers
Compatibility with future technology developments
Capability of allowing manufacturing facilities to modify/improve the processes based on their own requirements and capabilities.

For these reasons OMAC has been working on the ISO 10303-238 standard, also known as “STEP-NC”. Over a ten year period members have performed the series of tests described in the attached poster and found it enables the business advantages shown for their organizations.

“We are now ready to pilot the standard with our suppliers and would like you to develop the necessary system interfaces. Starting in late 2012 we will be holding a series of meetings to demonstrate the exchange of drilling (Cycle 1), pocketing (Cycle 2) and surface milling (Cycle 3) operations. We have a set of test parts and will be looking to you to demonstrate that sufficient data has been translated into your systems to enable the manufacturing and assembly of those parts. We will test the results in our laboratories and those of our partners worldwide,” Venkatesh added.

The meeting is by invitation only, but if you’re interested in this topic, send a note to Venkatesh via the OMAC Website to learn more.

Pre-Show Trial Run

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.

The group also discussed STEP kinematics models for machine tools, and showed a model of the tool changer on the Mazak. It 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.

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