Optimal processes

Ralph Hufschmied, managing director of the tool manufacturer Hufschmied Zerspanungssysteme GmbH in Bobingen, reports that his company primarily produces custom-optimized tools. “Starting from a standard design, we develop drilling and milling tools that are precisely tailored to the machining conditions, the materials to be machined, and the economic requirements of the manufacturing companies. In this way, we make a significant contribution to optimizing processes,” he explains, outlining the tool manufacturer’s concept. 

Thirty years ago, he and his father founded the company with this vision. Today, nearly 130 employees at Hufschmied produce high-quality drilling and milling tools based on this approach, primarily for materials that are difficult to machine and for specialized machining operations. This includes, for example, trimming and high-precision machining of components made of glass- and carbon-fiber-reinforced plastics for the automotive industry. The tool manufacturer also develops and implements productive and efficient processes and tools for machining high-strength, tough metals, such as titanium-aluminum alloys used in medical technology.

At Hufschmied, we are always open to innovation, as Ralph Hufschmied points out. That is why, a few months ago, we gladly accepted ZOLLER’s offer to work with the »mμFocus« optical device. 

This measurement technology is one of the pioneering innovations from the Pleidelsheim-based manufacturer. The collaboration offers ZOLLER the particular advantage of receiving feedback from tool manufacturers with practical experience regarding the function, operation, and measurement results. 

Ralph Hufschmied adds: Together with ZOLLER, we have consistently found the right measurement methods for our tool production for over 20 years. That is why we have been working with »genius« measuring devices for several years now. In this case as well, our experience and feedback have contributed to optimizing the measuring devices in terms of equipment and operation for practical use.» For this reason, both partners quickly agreed to continue jointly developing the innovative »mμFocus« optical measuring process using the knowledge gained in tool production.«

Finding the optimal tool measurement method

Repeated measurements of various tools have yielded insights previously unknown to Hufschmied tool manufacturers. Dr. Fuentes comments on this: “For example, in the case of milling tools, we measure the shank surfaces using touch probes. Despite optimal R_a roughness values, there were always tools that came loose from the hydraulic chuck or thermal tool holder due to cutting forces. So we measured them optically and obtained surprising results».” «

Thus, tool manufacturers discovered that the results of touch-trigger measurements depend heavily on the direction. This primarily affects tool shanks and the resulting transferable clamping forces. Furthermore, as Dr. Ing. Fuentes explains, touch measurement results are not always comparable with one another and cannot always be used to evaluate surface roughness. There are significant differences in tool behavior, even though the average and measured R_z roughness values of various tools may be consistent. 

In our experience, optical measurement methods and ZOLLER’s »mμFocus« inspection systems are sufficient for a detailed evaluation of the relationship between surface roughness and surface behavior in terms of clamping forces and tightening torques.

Extensive benefits 

Optical measurement with ZOLLER’s »mμFocus« inspection device offers specialists at tool manufacturer Hufschmied an unprecedented view of tool surface properties. For the first time, it is possible to measure and evaluate surface roughness across the entire surface, rather than just along a single line and in a single direction, as is the case with contact measurement. The »mμFocus« inspection device uses a light beam to capture a 1.0 x 0.8 mm surface area with a resolution of 1.3 million pixels. The surface image on the color display shows the height profile with a resolution of 0.3 μm in different colors. This allows the operator to comprehensively evaluate the captured and measured surface. This yields insights that were previously unexpected. For example, on some surfaces, such as the tool shank or the tool handle, a clear directional orientation of the roughness can be observed. This may be due to the grinding of the tools», reports Dr. Ing. Fuentes. «

The optical and microscopic measurement procedure also yields similar results on coated tools. While the arithmetic mean roughness value R_a typically measured is the same across the entire coating, significant differences are observed on surfaces measured with the »mμFocus« inspection device. This affects, on the one hand, the nature of the height profiles and, on the other, the roughness depths. To date, little is known about the actual geometric properties of tools with special coatings. Furthermore, with conventional measurement methods, microgeometries can only be evaluated in a general manner. In contrast, the innovative optical method using »mμFocus« inspection devices offers great opportunities for evaluating surfaces much more accurately and in greater detail.