In a darkened factory late in the evening, a five-axis machining center steadily drives a ball nosed end mill across the convoluted surface of a large Inconel impeller blade. Over a thousand hours of machining have already gone into this workpiece. The machine’s adaptive control system detects a rise in spindle torque and automatically reduces rpm, which drops below 12,000.

This event sets off a chain reaction. A signal goes to the controller’s telephone dialer and calls a pre-recorded pager number. Ten miles away, a manufacturing engineer reaches for the buzzing pager and glances at the message. She turns on her laptop, logs onto the company intranet and pulls up a menu of machines currently in operation down at the plant. The item representing the five-axis machining center is blinking. With a click, the laptop brings up the CNC’s operator interface screen where the engineer checks the live feed rate control.

Standard NC part programs can capture and send data generated by the CNC, distributing this vital information across an enterprise network.

It’s still within the range for the targeted chip load on the end mill, and only 20 minutes remain to complete this portion of the NC program, which repeats for the next blade. The engineer determines that there is no need to change tools before the scheduled change between blades. However, she decides to check the next tool after 2 hours in the cut, so she calls up the NC program from the file server and inserts a three line statement in VisualBasic Scripting to request that the CNC send an e-mail—at the 2-hour mark—with a list of every time spindle speed had to be overridden. This e-mail of real-time data will tell the engineer how well the next tool is performing. She saves the modified NC program and logs off the intranet. Checking e-mail before her morning commute will verify that the tool is performing to expectations.

Sound futuristic? It’s not.

In the past, it has not been possible to use a standard NC part program to trigger collection and distribution of data from a CNC as described in the scenario above. However, the latest version of OpenCNC from Manufacturing Data Systems, Inc. (MDSI, Ann Arbor, Michigan) now makes this data sharing possible. Version 5.1 of OpenCNC, MDSI’s all-software CNC system, allows manufacturing engineers to insert statements directly into their standard NC part program that request production data to be pushed to an enterprise resource planning program or back to the manufacturing engineer for analysis.

With conventional CNC systems, some collecting and sharing of data has been possible. Generally, however, this has not been quick or easy to set up. It could not be handled by a standard NC program. A custom macro routine could be written, tested and added to the NC program, but developing macros is time consuming and involves a high level of programming skill and proficiency. Another possibility would be to modify the programmable logic controller to include an interface to add-on sensors such as a timer or counter. Sometimes an outside systems integrator and/or network expert had to be brought in. Rarely could any of these activities be justified for applications involving short runs or single piece production such as in aerospace work.

MDSI’s new “smart” part programming technology takes advantage of two facts. One is that OpenCNC, by its fundamental design, is intended for real time data collection on the machine tool. The other fact is that a great many manufacturing engineers are familiar with Microsoft’s VisualBasic Scripting (VBS) language. VBS is a high level language that uses command statements to create computer routines for doing calculations and other data gathering and processing tasks.

This latest version of this CNC software includes a parser that recognizes and interprets these VBS statements when they are encountered while executing lines of a standard G-code (RS-274) NC program. So when a manufacturing engineer or programmer is preparing an NC program at the CAD/CAM workstation and sees a need to get key information about events that happen during machining to the right party, he or she can write the appropriate VBS statements, then simply cut and paste them into the NC program. The CNC takes it from there when the NC program runs at the machine.

For example, in the scenario presented earlier, the VBS statement inserted by the engineer from her laptap may have looked something like this:

Of course, the machine tool in this story had to be equipped with MDSI’s OpenCNC, which is applicable to almost all types of machines, including high-end multi-axis configurations. This CNC is a purely software-based system that runs on standard, off-the-shelf personal computers operating Windows NT on a single processor. There is no motion control card, proprietary hardware, or embedded firmware. The functions of all these devices are incorporated in software. The open nature of this system allows its data stream (all of the information about the events occurring while a part is being machined) to be accessed easily. The new “smart” part programming in Version 5.1 allows the NC part program to act as the convenient triggering mechanism for data collection and distribution routines.

This capability makes the machine tool itself an intelligent data-sourcing device in a company’s information loop. The trend today is to make that loop wide enough to include the entire organization via an intranet as well as wide enough to include the company’s supply chain via the Internet. As James R. Fall, president and CEO of MDSI, puts it: “By providing real-time production and process information automatically from the machine tool, we turn the machine tool into an essential business-to-business e-commerce communications device. The machine tool itself will supply the information about its operations that planners and decision makers need to respond rapidly to changing conditions.”

For example, the NC program could be edited to send an e-mail automatically to Maintenance or the manufacturing engineer whenever fault conditions critical to the production process are triggered on the machine tool. Probing/inspection data can be collected, then transmitted to a SQL or Oracle database for ISO9000 tracking by Quality personnel. For Production Planning, the NC program could be amended to trigger a command to send process times and part completions directly to the manufacturing execution system or to enterprise resource planning applications.

Other technology developments in Version 5.1 include:

• Rigid tapping. Two styles of rigid tapping are available, one for new machines with positioning servo spindles; and the other, a “soft” rigid tapping feature that allows older machine tools with non-positioning servo spindles to be cost-effectively retrofitted for rigid tapping.

• Support of SST DeviceNet I/O.

• Control of analog spindles via Profibus or DeviceNet.

• Pound sign (#) variables for NC macro programming.

As manufacturing becomes streamlined for the Internet age, the CNC machine tool seems destined to take on a more prominent role. A sentence from a recent MDSI news release puts their latest announcement into this context: “By allowing the NC part program to access the OpenCNC data stream, Version 5.1 enables global B2B for manufacturing from the heart of a CNC machine tool.” MMS