An alternative to produce doubly curved surfaces in fiber cement sheets using three-axes machining

Abstract

The present work describes the process and results of the machining of a cement-matrix composite material, which was reinforced with silica and natural fibers. This material is commercially known as fiber cement. This machining was carried out on a commercial sheet, having a 10 mm thickness and based on a double curvature surface in a ROLAND - MDX 40A machining center. This machining was performed through a roughing and subsequent finishing process in 3 axes, using some commercial tungsten carbide cutting tools. Rhinoceros 5 was used and complemented with Grasshopper, in order to obtain the geometry and the parameterization of the model. RhinoCAM was used to generate the G codes that allowed the machining processes execution. The geometry parameterized in the fiber cement sheet started from a Hyperbolic paraboloid module, with dimensions taken according to the plate measurements in length, width, and depth, and the number of times the user wanted to replicate this module in a rectangular pattern. The machining process was carried out without any refrigeration process, besides some standard cutting tools. Therefore, the main machining parameters as the speed, the cut-depth, and the tool advance were adjusted to the minimum set-points. This configuration allowed the preservation of the tool life and the care of the equipment during the machining processes. However, these parameters resulted in slow processing, which could have been optimized using cooling systems or machining tools of specialized ceramic materials.  The manufacturing technique used in this material and developed in this work can be applied to the low volume production of parts in fiber cement sheets. In this way, there could be applications in the Engineering and manufacturing sector parts, to the Electric sector, the construction and architecture industry, art and design, and furniture manufacturing.