Development of a Digital Standard to Specify Surface Requirements of Cast Metal Surfaces

Abstract

Communication of specifications between a customer and a manufacturer is important for meeting form, fit, and functional requirements of any part.Current standards for the requirements of cast metal surfaces use qualitative methods, including comparator plates and images of surfaces, to specify the surface quality allowing ample room for variation in interpretation of the standard. The length scale of existing contact surface measurements is too small for most casting surfaces. This paper covered a proposed digital standard for specifying cast metal surfaces. The proposed digital standard used point cloud data of a cast surface, likely attained using a non-contact capture method, in order to identify roughness properties and anomalies caused by the casting process. Unlike current qualitative methods, this standard does not specify the potential causes of surface issues, such as porosity or inclusions. This standard was developed in order to reduce measurement variation and eliminate confusion between the customer and manufacturer. Assigning quantitative criterion to the surface allows the customer to specify exactly what is needed as opposed to limiting them to a subjective comparator or image to base their requirements. Additionally, this quantitative method could be used to verify visual inspection results among the inspectors within a production facility to reduce their measurement error and improve productivity.

A Semiautomatic, Cleaning Room Grinding Method for the Metalcasting Industry

“…Currently, visual inspection of castings by an operator is required to identify anomalies; this method is very efficient as humans can easily adapt to product diversity. Research has been conducted to automate the isolation of anomalies and differentiating them from casting features by identifying the underlying geometry [20,21]; however, full automation is not feasible at this time. In this work, it is similarly assumed that an operator will identify the area requiring grinding.…”

A probabilistic model to estimate visual inspection error for metalcastings given different training and judgment types, environmental and human factors, and percent of defects

“…As long as there is a human element involved in the inspection process, various factors can affect their performance, which risk inaccurately determining whether or not a surface is acceptable. A digital standard is under development, which can be used to verify inspectors' judgments per customer requirements [16].…”

A process and investigation into the influence of cast surface condition on fatigue life

“…In turn, these methods provide a standardized and quantitative approach to evaluate cast surfaces and relate them to mechanical properties. Voelker and Peters identified the need for a quantitative standard to evaluate cast surfaces, indicating current qualitative methods as too variable for effective communication [20]. Voelker proposed a standard that was intended to provide objective means for a customer to effectively communicate cast surface specifications to a manufacturer.…”