Metrology equipment is showing its usefulness on the shop floor. Lasers and structured-light scanners operate next to assembly jigs and press-brakes. Some are hand-held while others are robot-mounted and rugged enough to work outside special quality rooms, giving manufacturers better control of their processes.
“Many manufacturers are not so much concerned about the absolute nature of what they’re checking. They just want to make sure that nothing in the process is changing,” explained Scott Everling, product business development manager for the North America Integrated Solutions group of Hexagon’s Manufacturing Intelligence Division, North Kingstown, R.I. Comparative gaging does the job, but it still needs additional checks to make sure it is maintaining dimensional accuracy. Parts are often carted off to a quality room for a proper dimensional inspection to absolute standards.
That may be changing.
With improved technology, metrology near or on the production line now produces results accurate enough and repeatable enough to provide dimensional verification. The cost and time savings of not having to move the part is enormous. “People are looking to understand how they can use that information more quickly at the site of the manufacturing experience, rather than waiting to get that information back from somewhere else down the line” or from a quality room, said Everling.
There is a more ambitious goal: closed-loop manufacturing. This is becoming more important in big, complex operations like manufacturing automotive body-in-white because of the increased turnover and model variety the industry deals with today, according to Everling. “Every time they turn those lines over, there’s a huge cost for all those OEMs in terms of getting that line up and running properly. And if they can reduce that time drastically, they can save a ton of money,” he said.
Hexagon offers a variety of equipment for shop floor metrology, including two lines of ruggedized CMMs: the SF series and the Leitz SIRIO series. The newest of the SF series is the TIGO SF with a measurement volume of 500 x 580 x 500 mm with a maximum permissible accuracy (E0,MPE) of 2.2 + L/300 µm. Hexagon designed it for the shop floor by allowing access from three sides and engineering its operating temperature range to an optional maximum of 15° to 40˚ C. Hexagon also offers lines of structured light systems, laser scanners and portable arm CMMs for use in or near manufacturing lines.
However, to create an information system, more than ruggedized, accurate metrology equipment is needed. The company’s MMS Pulse sensors measure vibration, temperature, humidity, crash notifications, luminosity, air pressure and the measuring machine’s current status—vital information needed for closed-loop manufacturing. In August 2019, Hexagon also released its Inspect 4.1. Inspect is a new stand-alone application that helps production-level CMM operators execute PC-DMIS measurement routines using a standard graphical interface.
The future is unfolding. Industry is trending towards mass customization. How does shop floor metrology fit? “If you’re really going to achieve that, make multiple parts and different configurations, a lot of the ways that we do manufacturing today are just not going to work,” said Everling. What’s needed is in-process metrology that is easily reconfigurable or collects mass-data. That spells the end of custom gaging and more CMMs, more scanners and vision systems.
“It is definitely evolving,” agreed Gene Hancz, product specialist for Mitutoyo America Corp., Aurora, Illinois. “They’re making strides at integrating metrology out on the shop floor during the manufacturing process, or right next to the manufacturing process at every opportunity.” He sees the reason as economic—reduced cost, engineering time and labor. In addition to CMMs like its MACH line of shop floor CMMs, Mitutoyo has introduced its newest CMM, the MiSTAR 555 for mid-sized workpieces on the shop floor. Mitutoyo defines mid-size in the measuring range of 500 x 500 x 500 mm.
Still, integrating metrology into a manufacturing line is not always the right solution. “You probably would not do it for smaller runs, like an order for 1,000 parts. It makes more sense for orders of 100,000 parts or more,” he said.
A key enabler for in-process metrology is a digital data foundation. Practically every manufacturer relies on CAD models. “It’s much easier to manufacture the parts from a CAD model when using a CAM system, whether it’s going to be on CNC machines, or if they are going to be turned or stamped,” he said. “Then you can use the same CAD model to program measuring machines like CMMs, and even vision machines to some extent.” The key element is the information attached to CAD—product manufacturing information (PMI) data with GD&T.
The exact format of that PMI data is vital. The emerging standard is ISO 10303-242. “If the tolerance information that’s contained in the CAD is not in a [242] format, if it’s only graphical representation of tolerance, then it is not usable” in an automated system, according to Hancz. He currently thinks that only about 10-12 percent of CAD models have the correct format of PMI attached. “But that is up from less than five percent five to seven years ago, so its use is growing, and it will continue to grow,” he said. “There is just so much time savings by using it.”
The standard is currently used more in aerospace than other industries. “Of the top ten users using STEP AP 242 as their guideline, eight are aircraft companies. That is mainly because it’s an ISO 10303 requirement,” he said.
Mitutoyo also recommends the MTConnect standard for real-time process data and the quality information framework (QIF) as important for driving factory intelligence of the future, helping to align suppliers and OEMs.
Even though Hancz sees metrology largely being integrated into manufacturing with large part orders, he also thinks it need not be confined to big orders or big manufacturers. “It doesn’t have to be a GE or a Ford that uses this because of how cost-effective collaborative robots have become,” he said. Cobots are small and easy to program, making them ideal for the right-sized product. “Establish using them with a big order, then re-purpose them for smaller ones,” he recommended.
Zeiss Industrial Quality Solutions, Brighton, Mich. is another company that offers shop-floor-ready machines, such the DuraMax, GageMax, and CenterMax CMM-style machines, as well as structured light scanning systems. According to David Wick, manager of product management for Zeiss, the bigger, more established companies are well into integrating metrology into their systems, while small and start-up manufacturers have yet to invest heavily in CMMs or other sophisticated metrology.
“In-between those two extremes is everybody else,” he said. These are the mid-level tiers, which may have plenty of metrology equipment such as CMMs and use them to measure products after critical machining operations. But the equipment may not be networked. Integration is incomplete. “Often, the measurement data from each operation is not pulled together and analyzed as part of a bigger process,” he said. Other than aerospace suppliers, most manufacturers don’t use sophisticated CAD models with attached PMI. These users may not know what next steps to take to leverage more from their metrology investments. “They may not even know if they want to take the next step to make their systems more productive, more analytical,” said Wick.
Zeiss CALYPSO and CALIGO are used to create measurement programs. Like most such programs today, they can do so automatically from a CAD import as long as the PMI is attached. This is ideal for manufacturing, so that staff in the manufacturing or quality departments don’t have to decipher written instructions on an accompanying drawing to create a measurement program. That also means the originating author in product design has interpreted the proper GD&T correctly.
Integration means combining data, analyzing it, and presenting information for decision making. “Our PiWeb software allows measurement results from any individual machine to be centrally stored on a customer’s server and then viewed by them anywhere, on their iPhone, in their office on their iPad, all around the country,” said Wick. It is already part of existing Zeiss software: Zeiss PiWeb reporting is available with CALYPSO and Zeiss CALIGO.
Do engineering designers need to have a better understanding of metrology and/or GD&T to achieve better results in an integrated system? “The answer is a qualified yes, but again, the sophistication depends on if the engineer is working for an automotive or aerospace OEM, or if they are working for a small start-up shop,” he said. Zeiss offers courses in the meaning and application of GD&T, how to create a measurement program, or how to achieve AUKOM certification (AUKOM is a global training standard for production measurement technology.) “Our ongoing education program is in-person and online, so customers have easy access to learn more,” he said.
Wick also noted both the importance of information transfer standards and their relative newness in the industry. “There are some elements of the QIF open standard that we support today, including reading PMI models from different vendors; the ability to create an inspection program automatically from those PMI models; and the ability to analyze and report out the results using our PiWeb software. Some of our larger customers have standardized on a QIF framework already. When we are developing new metrology software products, fitting that product into or how it nests into the QIF open standard is one consideration we go through. It is not the only thing we think about, but it is certainly one.”
The metrology integration gap is closing, but there are still many companies and users in the digital divide, trying to connect the dots, according to David Olson director of sales and marketing of Verisurf Software Inc., Anaheim, Calif. “CAD/CAM/CAE has been a collective term and reality for years,” he said. Olson thinks the critical missing link that maintains digital continuity and the all-important digital thread is computer aided inspection (CAI). “Once you have added the connection of CAI to your digital workflow, you are now at the doorstep of true model-based definition (MBD),” he explained.
MBD is a simple concept: a 3D dataset is the sole authority. The 3D model is the single source of data that provides all information for planning, manufacturing, sourcing, and inspection. According to Olson, a commitment to MBD continues to add intelligence to the CAD model. The beauty of an intelligent 3D CAD model is that it extends to reverse engineering, automated inspection and reporting, assembly guidance, product lifecycle management (PLM), as well as statistical process control (SPC). Olson thinks these elements embody the digital thread.
The concept of the digital thread is big and can be overwhelming for some OEMs and job shops to get their arms around. “But it all starts with a commitment to the intelligent CAD model and maintaining digital continuity,” said Olson. “Model-based measurement for reverse engineering, and automated inspection is a great place for many shops to start.” He believes this will get such organizations compliant with emerging OEM requirements addressing that digital continuity. The ultimate goal is true integration between CAD, CAM, CAE, and CAI.
Towards that end, he noted that standard file formats like STEP AP 242 or IGES are important bridges to move data from one platform to another. However, he also noted that true integration and compatibility is best handled at the application level. “For example, Verisurf software speaks CAD,” he explained. “The software directly supports, reads and writes files to Mastercam, CATIA, Inventor, KeyCreator, PTC Creo, Rhino, Siemens NX, Solid Edge, SolidWorks, and SpaceClaim” as well as supporting STEP and IGES file transfer formats.
“We take compatibility an important step further; we support and drive virtually any CMM, arm, tracker, scanner or other digital measuring device, including legacy CMMs that have been neglected because of outdated software and controllers,” he said. Verisurf developed software for these legacy machines to bring them back online, running the automated inspection software across all its CMMs.
“The common theme to remember when referring to a manufacturing system is ‘open platform compatibility,’ and that is at the core of our company and our software,” said Olson. “Moving forward you will see metrology and CAI synonymous with the digital design build process.”
Integrated metrology exists at a smaller scale, within machines as well as between them. “We launched our first touch probes for machine tools in 1982 and the first laser measuring system in 1987,” said Lilian Barraud, president of Blum-Novotest Inc., Erlanger, Ky. He believes they have become more than accessories. “It is now all part of the machine tool, all part of the manufacturing process.”
Blum-Novotest’s latest innovation, the LC50 DIGILOG for in-process tool measurement, is a good example. Coupled with a sophisticated laser source and protected high-end optics, DIGILOG technology is able to capture thousands of measurement values at the working tool’s rpm within seconds. Tool measurement, wear, breakage detection, tool identification, spindle health or run-out errors are automatically monitored in harsh conditions, including coolant misting and dripping inside the machine tool. But more is needed. Illustrating the importance of data analysis to integration, in 2019 Blum introduced its LC-VISION software, which shows on the machine control a live visualization of the data collected and provides optimization and diagnostic feedback.
Measuring systems like this help in multiple ways. “One purpose of our production metrology is to help make the first part good out of the manufacturing process,” said Barraud. “We want to end the costly trial and error upstream and the rework downstream.”
The other goal is a smooth, on-going operation, preventing mistakes. “It is easy to put the wrong tool in the wrong place, start the program, and crush a part,” he said. “In-process metrology is the best solution to ensure an efficient closed loop manufacturing process.” He emphasized devices need to be designed to work in dirty, oily, and noisy environments in order to close the loop and ensure quality through process improvement.
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