Quality Assessment of a Manufactured Bell Using a 3D Scanning Process.

Bells as percussion instruments have been known to humanity for ages. The casting process, the shape and the materials have changed over the years. The functional properties of bells depend on the casting quality and the generated sound. The casting quality is related to the shape, material and technology. The acoustic quality must fulfill specific parameters. This work concerns the assessment of the quality of the manufactured bells and the possibility of replacing tin bronze with a material with similar mechanical properties. Therefore, bell bronze-which is dedicated to this type of work-and aluminum bronze-which is characterized by high strength and hardness, have been applied to casting. The laser scanning technique was used to assess the quality of castings. Based on a point cloud, an optimized mesh was generated from which the 3D model was finally created. On the basis of the CAD model, the defects resulting from the casting process were determined in the form of graphical comparison. The correctness of the selected foundry shrinkage of the selected material was also determined. The manufactured bells were also assessed for sound quality. Vibration frequencies were determined using a vibration analyzer and free software Wavanal. The experimental results were compared with the ones obtained from the numerical frequency analysis. With the help of tests, the quality of the bells was assessed, and it was determined whether aluminum bronze meets the acoustic criteria. The presented method can be used in the development of bell templates. These templates will allow the bell to obtain the correct shape and acoustic quality without the need for a tuning process.