Design for manufacturing of surfaces to improve accuracy in fused deposition modeling

Fused Deposition Modeling is an Additive Manufacturing technology able to fabricate prototypes, tooling and functional parts without geometrical complexity limitations. Despite of the potential advantages of this technology, a limiting aspect of its industrial diffusion is the obtainable accuracy. The literature highlighted that significant deviations from the nominal values are observed: these deviations are not constant over all the part surfaces but strictly depend upon the process parameters, i.e. the layer thickness and the deposition angle. This involves poor surface quality: the parts could not satisfy the design specifications nor assure the functionality and the assembly fit with other components. The aim of this work is the development of a design for manufacturing methodology able to improve the dimensional accuracy obtainable by this technology. It operates in the design model step performing a virtual model preprocessing: an anisotropic offset is applied to the surfaces, defined by a mathematical formulation, in order to compensate for the abovementioned dimensional deviations. This way, without to eliminate the physical sources of the errors, it is possible to obtain a part with dimensional values very close to nominal ones. This method does not require any additional resources for its application such as preliminary artifact construction and measurements.