Introduction: Recently 3D printing has received an increasing attention on the area of actuators. It can provide design freedom allowing complex geometries, as well as customization, among other benefits. However, there is no research on 3D printing of hydraulic piston-cylinder s
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Introduction: Recently 3D printing has received an increasing attention on the area of actuators. It can provide design freedom allowing complex geometries, as well as customization, among other benefits. However, there is no research on 3D printing of hydraulic piston-cylinder systems. The aim of this article is to check the feasibility of 3D printing a hydraulic piston-cylinder system, as well as quantifying its performance. Methods: The same design was utilized for different 3D printing processes (Fused Deposition Modelling (FDM), Stereolithography (SLA) and Selective Laser Melting) and materials (Polylactic Acid (PLA), resin and Titanium), in order to be compared with each other and with conventional manufacturing of a system in Aluminum. Also, a second version of each piston-cylinder system was printed to use a reamer on them, to compare the performance between the cylinders with and without reaming. The followed methodology consisted of performing static and dynamic tests for each of the actuators. The output of the static test was the maximum fluid pressure that the system can handle. With the dynamic test a more realistic situation could be tested, from which the friction could be deducted and its results could be compared to the theoretically calculated data. Results: The results showed that the best performing 3D printed option was the reamed SLA resin version, reaching pressures of at least 4~MPa, with a dynamic friction force of 6.6~N, a stick-slip friction force of 9.9~N and a weight of 28~g. These features led to a force-to-weight ratio of 2928, only surpassed by the lighter FDM printed PLA actuator, reaching a value of 3565, but with higher friction forces. Conclusion: The conducted research means a first step towards the 3D printing of hydraulic piston-cylinder systems, demonstrating that it is possible to reach high pressures without leakage. The features that additive manufacturing offers, such as lighter and customized geometries in one assembly step, can benefit application fields where hydraulic piston-cylinders are used, such as prosthetic devices.