Permanent mold casting is the second largest production process in the casting industry (approx. 350 kt/a). The process is characterized by the molds' high acquisition and maintenance costs.
This makes the mold finish all the more important. In this context, the mold service life plays a vital role with regard to the mechanical quality of the surfaces of castings.
Due to the high working temperatures, only a visual inspection of the mold finish condition by workers has been possible so far. The quality assessment of castings and the service life of molds are therefore heavily dependent on the employees' work experience. As a result, stable quality management is challenging to implement. This is where the »MonCoat« project comes in, in which an automatic online monitoring system is being developed to check the mold coating condition. The system minimizes the risk of deviations and enables reliable evaluation of the mold coating condition.
Correlation between the topography of castings and the mold finishing condition
The »MonCoat« project is explicitly dedicated to the close correlation between casting topography and mold finish condition. For example, a thicker mold finish means a coarser mesh in the casting topography. Another result is that the surface roughness of the mold coating and the surface area of the castings also increases with the thickness of the mold coating. Thus, the surface of the castings can be inferred from the mold coating thickness.
Evaluation of the topography quality with gray images
First, different illumination systems are tested and a suitable exposure system is selected to control the exposure time. In this way, gray images can be taken that allow detailed information about the topography (peak and cave).
Connection of a 7-axis robot with a camera
The project's overall goal is to use camera images from a camera connected to a 7-axis robot. Based on the detailed photos, measurement data for different topographies of castings can then be obtained and the corresponding finishing condition can be traced. To enable the study of topography based on the images at many different locations, the camera is connected to the robot. Target value images are derived by evaluating microstructure castings using metallography.
At the end of the project, the demonstrator, which is a camera connected to a robot, will analyze the casting topography with different contours and sort them according to surface quality.
Fraunhofer Institute for Casting, Composite and Processing Technology IGCV