Plugging into STEP NC - Emphasis: CNC - CAM software firms offer programs for CNC machines
CAM software companies are offering software programs that allow their users to read STEP-NC files info their existing CAM software to generate the tool path and output for specific CNC machines. These "plugins" make many of the benefits of STEP-NC available to the average machine shop today.
The concept behind STEP NC is simple. It enables a product model database to serve as direct input to a CNC machine tool. No separate files of tool paths. No G or M codes. No post processors.
This is a radically different approach to CNC programming. It has far-reaching implications for the emerging possibilities of "e-manufacturing." Recent developments, however, promise to make it easier for CNC machine shops to make the transition to this technology Without scrapping existing machine tool and CNC programming technology, shops now have a way to implement key aspects of STEP-NC.
Several leading CAM software companies have made it possible for STEP NC files to be used with their own software. This makes their users ready to participate in supply chains that are turning to global data exchange standards to streamline the flow of digital information over the Internet. According to STEP Tools, Inc. (Troy, New York), a leading supplier of STEP software toolsets for application software developers, design firms and manufacturing companies, STEP NC offers significant savings to machine shops and their customers. The company estimates that, by fully implementing STEP NC, machine shops can reduce the time it takes to get jobs onto their machines by 35 percent if they can seamlessly read the 3D product geometry and manufacturing instructions of their customers. Likewise, original equipment manufacturers can reduce the time they spend preparing data for their suppliers by as much as 75 percent if they can seamlessly share the design and manufacturing data in their databases.
STEP Tools also estimates that STEP NC will reduce machining time for small- to mid-sized job lots by as much as 50 percent because STEP NC compliant CNC units will be capable of optimizing speeds and feeds with very little intervention from CNC programmers or machine operators. This factor could make it easier and safer to program high speed and five-axis machines, the company says, making it more likely that they will be used for small- to mid-sized job lots.
STEP NC In A Nutshell
STEP NC is an extension to STEP, the STandard for the Exchange of Product model data. STEP is the international standard that specifies a neutral data format for digital information about a product. STEP allows this data to be shared and exchanged among different and otherwise incompatible computer platforms. STEP NC standardizes how information about CNC machining can be added to parts represented in the STEP product model.
By using STEP NC to capture instructions on what steps to follow for machining the part, the "producability" of this part would not be affected by the availability a certain brand of control unit, programming system or post processor. Figure 1 compares the key features of STEP NC to current conventional approaches to creating CNC machine tool input.
If equipped with a STEP NC compliant CNC, any suitable machine tool could be designated to make the part. Because a product model database can be made accessible through the Internet, this designated machine tool could be linked to this global network virtually anywhere on earth. For manufacturing enterprises participating in a highly competitive global supply chain, this kind of flexibility is crucial. With the Internet acting as a global DNC system, the world becomes one big job shop.
Step Rather Than Leap
The availability of STEP NC software plug-ins for CAM software puts STEP NC within the reach of many shops. Currently, plug-ins are available for Gibbs CAM from Gibbs and Associates (Moorpark, California) and for Mastercam from CNC Software (Tolland, Connecticut). A plug-in for Esprit from DP Technology(Camarillo, California) will be completed soon. With these plugins (or "add-ins," as they are also called), a shop can take in a customer's STEP NC files and produce parts on existing CNC equipment.
A full implementation of STEP NC would involve equipping machine tools with CNCs customized with special software. This software enables the CNC to interpret the STEPNC data directly and use the information to machine the part without a conventional G-code program. This software is currently under development.
Machine tools with PC-based open architecture control systems may be able to install this software to upgrade to STEP NC compatibility rather effectively. The conventional input/output (I/O) structure and the servo system of the CNC machine do not need to be modified under STEP NC.
