The wbk Institute of Production Science at the Karlsruhe Institute of Technology (KIT) has teamed up with Dentsply Sirona, the world-renowned manufacturer of dental products and technology, to achieve the same goal of reducing noise and vibration in dental instruments.
The project, named ProIQ, is investigating the function-oriented quality assurance of micro gears by integrating inline measurement technology. The main objective is to adaptively control the hobbing process to enhance component quality while limiting waste and scrap. In this project, the µCMM optical coordinate measuring machine from Bruker Alicona is the ideal instrument of choice.
Image Credit: Bruker Alicona
Key Functions of Complex Products Require High-precision Components
The increasing use of high-precision components with tolerances of a few µm and the trend towards miniaturization present significant challenges for manufacturing companies. Vivian Schiller and Daniel Gauder are Ph.D. students at the wbk Institute of Production Science at KIT who are working to address these issues.
For the global dental product manufacturer Dentsply Sirona, Schiller and Gauder are researching component pairing strategies, intelligent quality control loops, and measurement technology (inline and in-process) for the manufacture of high-precision components.
Their main goal is to produce quality control loops for the purpose of closed loop manufacturing. Thus, introducing inline metrology into production systems enhances product quality and boosts efficiency in production.
The BMBF (German Federal Ministry of Education and Research) is providing funds for the project as part of its photonics program, which includes testing the suitability of Bruker Alicona's µCMM optical coordinate measuring machine in such an environment.
Reduced Vibration of Dental Instruments
After the µCMM was installed at the KIT institute, it was directly integrated into Dentsply Sirona's production environment on the shop floor.
As part of the ProIQ project, we measure the surface topography of micro gears with involute profiles in the module range smaller than 0.3, focusing on the tooth flanks. Geometric parameters are then extracted from the captured point clouds. In addition, we derive function-oriented parameters, such as the rotary path deviation, from the point clouds.
For example, small deviations tend to lead to a reduction of vibration in dental instruments - which offers an advantage to both dentists and patients alike.
Due care and attention must be given to both the surfaces and steep flanks of the metallic components due to reflections; as Vivian Schiller explains, "The tooth root area poses the greatest challenge, since the opposing flanks of a tooth space converge in this area."
Image Credit: Bruker Alicona
Low Measurement Uncertainty and Short Measurement Times
Other systems were also considered during the project preparation phase to help determine what the right measuring system was for this task. Generally speaking, criteria – such as information density, measurement speed, and measurement uncertainty – play a key role in the field of microgear measurement technology.
While for some time now, tactile methods have been with low measurement uncertainties, inline integration presents a particular challenge due to the filigree geometries. Volumetric measurement systems offer a high level of information and facilitate 3D acquisition even with undercuts. They also have a relatively high measurement uncertainty, meaning longer measurement times are necessary.
Ultimately, the µCMM scored with focus variation: "If the workpiece material is optically cooperative and undercuts are not considered reasons for exclusion, focus variation offers non-contact, two-dimensional measurement recordings with high measurement point density," says Vivian Schiller.
When investigating the various systems, special considerations were given to short measurement time and low measurement uncertainty.
Increased Component Quality with Less Scrap
Amongst the significant advantages the measurements provide, standard parameters (VDI/VDE 2612) and function-describing parameters (after single-flank rolling test VDI/VDE 2608) can be derived based on the measurement data recorded inline.
It is also possible to achieve sustainable quality improvements; starting with the assessed parameters, the hobbing process can be adaptively controlled, which means improved component quality with less scrap.
Artificial Intelligence for Function Prediction of the Entire Product
In the near future, the KIT research team aims to introduce artificial intelligence (AI) into their research.
Moreover, as well as adaptive control of the hobbing process, a method for adaptive assembly of micro gears is in development. This is based on the measurement data and the features taken from the point clouds, from which AI models are able to predict the function of possible microgear pairs. Subsequently, an optimization algorithm can facilitate the individual or selective assembly of the gears produced.
Inline Capability as a Prerequisite for Closed Loops
As the first completely optical coordinate measuring machine, Bruker Alicona's µCMM makes use of just a single sensor to establish the dimension, position, shape, and roughness of components, irrespective of material and surface condition.
Focus variation facilitates optical, high-resolution 3D surface measurement at the micro and nano scales, while for the first time, Vertical Focus Probing enables optical lateral probing of components (even with flanks exceeding 90°) over the complete surface.
Thanks to various system and technology features, it is possible to integrate the system into a closed-loop manufacturing strategy. The combination of robust technology and the stable, production-grade hardware assembly of the measurement system and automation options allows repeatable measurements in production environments.
These features are supplemented by simple, user-independent handling, which was specifically developed for operation on the shop floor. For the different automation options, a robot arm can be fitted to extend the µCMM, making it possible to pick up, place, measure, and sort components. Thus, a complete automation process can be delivered within a short time.
Networks for Self-optimizing Production
Given the potential to connect the measuring system to pre-existing IT systems and thus also facilitate the concept of "machine to machine" communication, the requirements profile regarding closed loop is complete.
Interfaces, such as .net remoting and different connection options (e.g., QDAS) or a CAD CAM connection, facilitate optimal networking and communication with existing machines, production systems, and quality management systems.
This information has been sourced, reviewed and adapted from materials provided by xBruker Alicona.
For more information on this source, please visit Bruker Alicona.