Contact Zone Force Profile and Machining Performance of Filamentary Brush¹

Filamentary brushing tools are used in a wide range of surface finishing processes, such as deburring, edge radiusing, polishing, and surface decontamination applications. Moreover, these tools are easily adapted to automation because the filament tips, which perform the machining operation, readily conform to the workpart surface without the need for sophisticated control systems technology. However, little is known about the material removal mechanics of filamentary brushes and, therefore, trial-and-error experimentation is often necessary before the tool is implemented in a production environment. This uncertainty of performance can be traced to a lack of understanding of the actual forces that are generated within the contact zone, that is, along the interface of the filament tip and workpart surface. Although previous experimental research has focused on the overall (i.e., resultant) brush force exerted onto the workpart, no information exists in the literature regarding the variation of force within the contact zone. Such information is essential for understanding the material removal profile within the contact zone, and could provide valuable information regarding the most active machining site along the contact surface. In this paper, a novel experiment is proposed for evaluating the force profile of filament tip forces that are generated within the contact region of a brushed surface. A specially designed workpart fixture is constructed and used in conjunction with a multiaxis force sensor for measuring the detailed force variation within the contact zone. The experiment is conducted using a wire brush at several different rotational speeds, which enables one to ascertain the role of filament inertia in the material removal process. Findings are reported which suggest that a significantly enhanced material removal rate can be achieved at a selective location within the contact zone at moderately elevated spindle speeds.