WIRE & CABLE TECHNOLOGY INTERNATIONAL SEPTEMBER 2024
One small handful of rejected materials, identified during a run of 30,000 high-precision components, is one handful too many,” asserts John Pechan, Chief Operating Officer at Round Ground Metals® (RGM®). This commitment to quality is the cornerstone of the collaboration between RGM, a producer of close tolerance high quality round rod and bar and Magnetic Analysis Corporation® (MAC®), a global leader in NDT systems for over 95 years. They joined forces to create a fully automated test system that incorporates eddy current and ultrasonic NDT technologies. This system features seamlessly integrated handling and conveyors to test cold-finished carbon, alloy, and stainless bars destined for high-quality parts used in critical components. The massive system - more than 100 feet (30m) long overall - can test bars ranging from 12' to 42' (3.66 - 12.80m) long and 0.75" to 3.5" (19.05 – 88.9mm) diameter, at speeds up to 150 fpm (45.72 mpm).
A Story of Perseverance and Innovation
The story of RGM begins with its founder and President, Andrew Strzalkowski, who as a young teenager in communist Poland, used perseverance, an ability to engage with people, and some good luck, to find his way to the USA at age 18. Unable to speak English, he started work at a Polish gas station and from there worked several years at a bar grinding business. Frustrated by the lack of ownership equity despite his hard work, he founded his own grinding shop in 1987. Implementing his vision for the kind of company he wanted to build – insisting on a quality product, listening and acting on customer needs, reinvesting in the business, and expanding to meet the market – what started in 1987 with a building of 10,000 ft2 now takes up 510,000 ft2.
RGM® Operator prepares bundle of pre-aligned bars for transfer after testing.
Bird’s eye view of MAC®’s 105 ft, ultrasonic and eddy current equipped NDT system with automated materials handling at RGM®’s Illinois plant.
Today, RGM (located in Hanover Park, IL, USA) is recognized as a premier producer of bars in the USA market. MAC, founded in 1928, shares RGM’s vision for quality, meeting customer needs and innovation. Bill Hoffmann, MAC’s District Manager, affirms this approach: “We’ve always been dedicated to a production-oriented approach.” This commitment has led MAC to continuously integrate with mill operations, adapting to new production conditions, and developing cutting-edge NDT capabilities. MAC’s dedication to customer support extends beyond delivering test systems. They provide comprehensive service from design to installation ensuring the system is fully operational and optimized for performance. This end-to-end cooperation reflects MAC’s desire for their customers’ success, with field engineers engaged through every phase of the project.
As RGM emphasizes, having a testing system like the one provided by MAC isn’t just an option—it’s essential. RGM’s President explains, “The machine we have now is opening new areas of application. These applications—medical, aerospace, etc.—are more demanding of the metal.” As customer specifications and expectations become more stringent, companies like RGM and MAC rise to the challenge, embracing advanced solutions to meet evolving demands.
By working closely with RGM, MAC designed a system tailored to their requirements. Matt Schubert, Director of Quality at RGM, remarks on this synergy: “MAC had previously supplied us with an eddy current test system for small diameter rods. Due to a recent plant expansion, we decided to bring our eddy current and ultrasonic NDT in-house for larger diameter stainless bars.” This strategic move was driven by a desire to provide faster service and maintain full control over product quality, reinforcing RGM’s commitment to excellence.
From the moment when the plant expansion was first discussed, MAC’s engineers and Business Development Manager worked with RGM Quality Control and Managing personnel to develop a system. It had to meet their needs for efficient and superior test quality and do so without harming the bar surfaces. Strzalkowski emphasizes the importance of early collaboration: “We’ve always believed in working with suppliers at the earliest stage possible. The best results come when very specific needs are expressed and exchanged during the initial stages of design consultation.” This proactive approach facilitated the successful implementation of the new system and sets the stage for future collaborations.
Inside MAC’s State-of-the-Art NDT System
MAC’s cutting-edge NDT system, designed for thorough inspection and quality assurance of metal bars, spans 105'. (32 m) and incorporates input/output tables, stop arms and pneumatic release mechanisms to ensure smooth handling. It features automatic sorting to separate defective bars, allowing only acceptable bars to proceed for bundling. Triple pinch benches with guide rolls provide vibration-free entrance and exit from the testing, while automatic height adjustment adapts to various bar diameters for consistent precision. The system also includes an automatic feed for calibration bar standards to maintain accuracy through periodic calibration. Combining eddy current testing (MAC Rotomac®) for surface defects and ultrasonic testing (MAC Echomac®) for internal flaws, this system exemplifies MAC’s commitment to quality, providing a robust and reliable solution for comprehensive material inspection.
Choosing the Best Technologies for This Application
Eddy Current: One of the earliest decisions RGM and MAC had to make was to agree on the optimum test technologies for detecting both surface defects and internal flaws. The industry method of choice for detecting long seam-type surface defects, including cracks, pits, and laps, is eddy current probe equipment such as MAC’s Rotomac rotaries used with MultiMac electronics. As the bar moves forward, the test probes rotate creating a helix pattern. This pitch, a function of the probe’s rotational speed, throughput speed of the material, and number of test probes, governs the defect length that can be reliably detected. The Rotomac 350 two channel model being considered for this system has two probes that spin around the bar at 3000 rpm. MAC advised RGM that at throughput speeds of 150' per minute, defects as short as 0.4" to 0.5" could be reliably detected. Slower speeds would allow shorter length defects to be detected. Depending on the material quality, Rotomac 350 is capable of detecting defects smaller than 0.004" deep. Knowing this data, MAC and RGM could confidently move ahead with a system design that would meet their goals. Current operation at the mill for uninterrupted testing flow is commonly 120 fpm, typically set up on 0.010" depth notches.
At input, bars enter through a demagnetizer before eddy current testing. On the left, a sample bar is held in the calibration station where it can be automatically fed through the testers when needed.
MAC®’s Aligner ensures the accepted bar ends are lined up for easy bundling.
To optimize the eddy current test accuracy, the bars pass first through a MAC Demagnetizer 470 which removes existing magnetic fields in the steel bar that might counteract the fields induced by the eddy current probes during the test.
Ultrasonic: To detect internal flaws in the bar, ultrasonic technology was selected. Ultrasonic transducer test signals can penetrate the entire body of the bar, allowing a 100% volumetric inspection to detect core internal flaws, such as cracks, voids and inclusions, as well as some surface flaws. This differs from eddy current technology, which can only test the surface and some subsurface. MAC and RGM selected the Echomac FD-6 eight channel ultrasonic electronics and 100mm rotary. The rotary head mechanism spins the transducer elements and water couplant at speeds up to 2400 rpm around the bar as it is fed through the test. The transducers are housed in holders that facilitate fast setup for different size materials. The rotary’s unique seal-less design ensures minimum maintenance requirements and deters problems that can result from debris on the bars contaminating the water system.
The Environmental Cabinet: A large environmental cabinet houses the MultiMac and Echomac FD6 electronics, along with MAC’s Multi-Collector software. Each instrument has a keyboard and mouse which can also control both instruments. The operator can enter setups, make changes and create customized reports. Monitors display real-time test signals and charts, which can be stored locally, on a network server, or exported as .csv files for analysis. Access can also be provided from the customer’s internal network. The Multi-Collector software package displays test information from both the MultiMac (EC) and the Echomac (UT) instruments on one screen display. It is based on an open-source format SQL database that can be used by the customer to access all results from both tests. Test results, all test parameters, production, and operator information are stored and automatically attached to the record for each bar to provide full tracking of all data.
Developing the Design of the Automated Material Handling System: Sometimes referred to as the “heart-of-the-system” the MAC Triple Bench contains the testers, motors, and triple drive rollers that accurately position and move the bars through the tests. The eddy current and ultrasonic rotaries, demagnetizer, paint marker, and an air knife are all mounted on this highly automated bench, requiring virtually no manual settings when dimensions are changed. Leading and trailing triple guides guarantee a controlled entrance and exit from the test stations, eliminating vibrations that can cause false reject signals. The bench height is set automatically for new bar dimensions, and it includes slide mechanisms for the rotaries to allow offline setup and maintenance. Managing the entire system, a conductor PLC with an HMI touch screen controls all operations of the rotary testers, triple guides, conveyors, sorting, alarms, marking, and monitoring paint supply.
MAC and RGM paid special attention to the design of the automated material handling system to maximize efficiency without back-ups, jams, or damage to bar finishes. Bars ranging from 20 to 100 mm diameter are loaded from the input tables, with no adjustment for size needed. When a bar is released, MAC’s EZ drop rollers carefully place it on the conveyor channel rolls where it moves smoothly through the testers.
On the output side, tested bars are automatically sorted into accept or reject pockets. As each accepted bar is conveyed out of the test station, it is lifted by sorting rollers and moves to an intermediate station where it is raised by alignment rollers. Here, the MAC Aligner unit pushes the end of the bar to line it up correctly before it is released onto the accumulation table and into the accept pocket, making bundling much easier. When the accept pocket is full, stops may be activated to allow bars to accumulate while the pocket is emptied without having to stop testing. The operator can then release the accumulated bars into the accept pocket. RGM found these features particularly satisfying, as they enhance the bundling and packaging operation overall, demonstrating the benefits of the joint innovation between the two companies.
The system includes MAC Rotomac® and Echomac® test rotaries that detect surface defects and internal flaws. The slides in the foreground allow easy access for maintenance of the rotaries.
The “heart-of-the-system” triple pinch controls the entrance and exit of the bar as it passes through the test. This signature feature eliminates vibrations that can cause false rejects, saving time and labor.
Reference Bar Calibration Station: A specially designed calibration station was added to the system to hold and feed bars used as reference standards. Calibrations verify that the tests are operating within specifications. In the MAC and RGM system, a button press moves the bar from the calibration support station to MAC EZ drop rollers which catch the bar and carefully let it down onto the inlet conveyor, where it is automatically fed through the tests and then reversed and returned back to the station. Calibration checks are done during setup, between bundles and after the production run. With the MAC calibration station, this becomes a simple, efficient operation that avoids the wasted effort and inefficiency common in many mills where reference bars must be brought by crane from some other part of the building every time a calibration is specified.
Partner with Confidence
MAC’s state-of-the-art NDT system has become an indispensable part of RGM’s operations. Testing cold-finished carbon, alloy, and stainless bars at high speeds, the system ensures that every bar meets stringent quality standards before proceeding to the next stage. The seamless integration of eddy current and ultrasonic technologies provides a comprehensive assessment of each bar, from surface to core, identifying any potential defects that could compromise the final product.
Demonstrated with RGM, MAC prioritizes strong bonds with all their project partners. Proactive engagement, expertise sharing, long-term collaboration and a commitment to quality define MAC’s approach to client relationships. The advanced capabilities of MAC’s NDT solutions, combining both eddy current and ultrasonic testing technologies, ensure RGM’s buyers of high-quality, close tolerance round bars without damage to their finishes. Through continuous innovation and a customer-centric approach, MAC remains a leader in the NDT systems industry, providing reliable and high-performing solutions to its valued partners. This partnership is about both companies’ unwavering dedication to their customers’ success.
The relationship between MAC and RGM is a testament to what can be achieved when two industry leaders combine their expertise and resources. By leveraging MAC’s advanced NDT technologies and RGM’s commitment to precision and quality, the partnership has transformed quality assurance processes and ensured the highest standards in bar production.
MAC is with you every step of the way from initial consultation to ongoing support, Dan Lawrence, President and CEO for MAC on this, “Our relationship with RGM epitomizes MAC’s technique: we will actively seek out and solve difficult customer problems through a collaborative solution, and focused approach that provides our customers with the lowest total cost of ownership available in the marketplace. This technique has served us well for nearly 100 years and we expect it to continue to serve us well for the next 100.”
