4D printing by fused filament fabrication of a rotary diverter valve: study and optimization of the manufacturing process

4D printing is an interesting fabrication process that integrates the advantages of additive manufacturing technologies and the characteristics of smart materials to fabricate dynamic structures able to modify their shape over the time if they are subjected to stimuli such as heat, light, pH, moisture, electricity, and magnetic field. This permits to expand the applications fields of Additive Manufacturing potentially revolutionizing the manufacturing of intelligent components. In this paper, an integrated methodology based on the design, fabrication, programming and recovery of a rotary diverter valve is presented. The 4D printing, using Fused Filament Fabrication technology and polylactic acid material, is used to fabricate the component. The valve is designed in a unique part and the functionality to open and close is permitted from the capability of the material to rearrange its structure when it is programmed and then activated by a thermal stimulus. This way the valve can work without the need of sensors and actuators. Since the additive process parameters have impact on the dynamic performance of the fabricated components, their effects were studied in terms of shape recovery percentage, recovery ratio and fixity using digital image analysis techniques. The results of this analysis were used to develop prediction models of recovery percentage, recovery rate and fixity as function of the Fused Filament Fabrication process parameters. The multiple response optimization was also used to have a useful tool to integrate the information provided by these models.