Metrology Matters

Measuring optics is a precision practice, and it’s made possible with laser interferometry. In this episode of Metrology Matters, host Tyler Kern kicks off a series on laser interferometry with an introductory episode discussing the practice with Kate Medicus, CEO of Ruda Cardinal, and Bruce Truax, Director of Engineering at ZYGO, to delve into this core technology and to better understand its many use cases in numerous industries.

World Metrology Day celebrates the importance of metrology. This year’s theme is Measurement for Health. Discussing the value of metrology and its relation to healthcare, Metrology Matters host Hilary Kennedy spoke with Eric Felkel, Product Manager at ZYGO.Felkel first explained what metrology is. “It’s the science of measurement, and it’s a part of our daily lives. If you can’t measure it, you can’t make it, no matter the industry of product.”Metrology applies to so many aspects of machined parts, including those that go in the body. Its use in manufacturing these components has to be exact. “Incorporating metrology from the beginning as part of the process is key to making what you intend to make,” Felkel said. In the context of healthcare, components require well-documented manufacturing procedures, and these include the metrology. Felkel shared some of these specific use cases. “Replacement joints and implants are the most common. They are machined surfaces that move in the body and interact with other surfaces. Metrology ensures these implants are long-lasting.Additionally, metrology plays a role in contact lens molds, continuous glucose monitoring devices, and pacemakers. These measurements must be accurate before mass production, reiterating the importance of metrology.

In this episode of "Metrology Matters," two experts in the field, Dr. Mark Malburg of Digital Metrology and Mr. Carl Musolff of Musolff Consulting, discuss how to get the most out of 2D and 3D surface parameters. Their years of front-line experience provide valuable insight into precision manufacturing processes and why choosing the right type of metrology and examining the correct parameters are critical to understanding and controlling the manufacturing process. Listen in to discover what should be considered when implementing surface texture specifications on engineering drawings and why an understanding of the function of a part can contribute to more effective and reliable manufacturing processes. A key takeaway is that data is more than just numbers… 2D line profiles and 3D surface maps provide a wealth of information and insight into the surface and what is likely happening during the manufacturing process.

For this installment of Metrology Matters, Srini Varre, Technical Specialist at Global Power-Train, and Dave O’Leary, Director of Quality Assurance, at Accumold lent their expertise to help break down the world of metrology equipment. A question often asked is, ‘what’s the right metrology for my parts?’ Varre and O’Leary came equipped with some answers. Using Global Power-Train as an example, Varre said, “When we take a look at any program, for us it’s when a new powertrain comes in. Whether it’s an electric powertrain or hybrid powertrain, if it’s an existing product design and we’re just taking a look at some of the components of the powertrain and trying to improve the performance, the parts community comes out they will try to reduce the tolerance.” The process varies depending on if it is a whole new design or just a design enhancement or refinement. For O’Leary, metrology considerations come into play as soon as his company quotes a job. “We look at it right up at the front end, we review the models and the prints to see what types of tolerances are required, and make sure our metrology equipment is capable of handling that and getting the data we require,” O’Leary said. “A lot of the customers are very specific based on their industry and also wanting data. We have to look at not only measuring the parts but capturing that data.” “The tolerance of the feature is the most critical component we look for,” Varre said. “Because as the tolerances get tighter, the requirements and the metrology equipment become more stringent in terms of maintaining it to get that accuracy.” And while Varre said in-house, they have a set of standard metrology equipment they use, if a project calls for a requirement the equipment can’t measure, they’ll procure a metrology gauge to satisfy it. 

It’s an important first question to understanding the field, and one perhaps too many mechanical engineering students don’t stop to ask. Jack Clark, Senior Principal Scientist at Woodward, and Chris Evans, Professor of Mechanical Engineering and Director of the Center for Precision Metrology, said the answer isn’t easy, but understanding what metrology is can open many doors. “By definition, metrology is the science of measurement, but it’s also, I think, foundational to many things from fundamental research – without the science of measurement, we never would’ve been able to recently prove that gravity waves exist,” Evans said. “It’s foundational to us being able to have this conversation. Without metrology, the semiconductor industry would absolutely not function. It’s foundational to commerce. If you don’t have internationally agreed standards on what length is, what volume is – you can’t make components that will assemble.” Despite so much being built upon metrology, there is currently little attention being paid to it by many educators, even in some of the nation’s top engineering schools. Partnerships with companies can be critical for students to begin understanding that aspect of the engineering and design world. “They generally have little knowledge of (metrology),” Clark said of students doing internships or projects with companies like Woodward. “If they’re involved in any kind of design when they’re introduced to the company, if they’re involved in any troubleshooting, they may be brought into remanufacturing in the company. “They have to start understanding what the metrology role is in all those different things and how it is different when you start looking at all the aspects of manufacturing and remanufacturing parts.”