Efficiency through collaboration is the goal of product lifecycle management (PLM) software providers. There is a lot of inefficiency at interfaces. Transferring information and using it to create instructions automatically for the next step, say from CAD design to machining or inspection, is an inviting target for this process. The newest release of Siemens NX 7, announced in May, adds more tools in its PLM offering. Among the enhancements in the new release of NX 7, the new CMM Inspection Programming module stands out in connecting design data to measuring the final part, reducing one more friction at an interface.
“Annotated drawings are still used today in many shops to capture and convey information about how the part has to be made—requirements like geometric, dimensional, and positional tolerances or surface finish,” explains Vynce Paradise, Director of Product Marketing for Siemens PLM Software. Attaching and storing this additional, nongeometric data to a geometric CAD model is what Siemens calls "product and manufacturing information" (PMI.) “PMI covers a broad spectrum of information that can be attached to the 3-D model. However, the trick becomes not only communicating that downstream but being able to use it in some fashion to drive those applications, and to date, that has been quite an immature process. To have software use it downstream [from CAD authoring] as opposed to a purely manual process... We now have two modules that use that PMI information to automate downstream programming.”
The new CMM Inspection Programming module in NX 7 is the latest addition to use PMI data for downstream programming. The first is Feature Based Machining (FBM), a module within NX CAM released in early 2009 that uses PMI to generate automatically CAM programs. Siemens PLM Software customers report an 80% reduction in NC programming time using FBM in NX, according to the company. Siemens also points out that automating CAM programs also reduces mistakes common to manual programming such as the wrong tool selected, wrong holes picked for operations, or features that are missed all together.
Building on this module, the CMM Inspection Programming also uses feature recognition algorithms as a foundation. Speed and efficiency are the key benefits of the new CMM Inspection Programming that Paradise stresses. Coordinate measuring machines (CMMs) are the mainstay of many inspection processes. These require involved parts programs, especially if the part itself is complex. Using the PMI data attached to a CAD model, the module identifies and establishes inspection features from that information and then establishes, automatically, an inspection process. “The CMM Inspection Programming module is fast—very much faster than having to bring a model up [on a screen] and then select measurements point by point,” explains Paradise. Siemens again reports programming gains of 80% to 90% over current methods.
He notes that many current off-line programming tools for CMMs emulates a teach-in procedure one would use with a real part on the physical machine. Siemens new module avoids this manual process. The module also offers multilevel tool-path simulation and machine simulation to verify the program is correct. If not, the user makes changes manually. Alternatively, users could create them manually from scratch. “We believe this automatic process is unique,” states Paradise.
The program outputs standard Dimensional Measuring Interface Standard (DMIS) 5.1 program instructions or a native programming language, such as offered by suppliers of CMMs. Siemens provides CMM and probe models along with an edit capability to create custom models. The software supports three-axis scanning and up to five-axis touch-trigger probing.
Another key feature where Siemens may stand out is this program’s back-and-forth connection to the source data. Since both the FBM and CMM programs are built inside NX, they are connected with Teamcenter, the popular PDM system. For design change control, associativity is used to quickly update programs to reflect design changes. “The whole concept of integrated manufacturing is to take a model and move it downstream to automate the definition of machining and inspection processes,” remarks Paradise. When the model changes, those changes are more conveniently flowed downstream with associativity assured and the updates managed through the combination of NX and Teamcenter.