Exploring the performance of 3D-printed custom piston-cylinder systems

Background Pneumatic actuators are widely used in applications like (medical) robots, or prosthetics. They require tight tolerances to keep them leakage-free. Over the last decade 3D-printing, or additive manufacturing, has emerged as a cost-effective production method in these applications.Objective The goal of this research is to study the possibility of creating a pneumatic linear actuator with additive manufacturing. The focus is on finding sealing mechanisms which can have a positive influence on preventing leakage and friction force in the 3D-printed actuator. Furthermore we aimed to use the advantage of 3D-printing to create pneumatic actuators with a non-circular cross-section.Methodology To evaluate the performance of a 3D-printed pneumatic actuator, a test setup is designed to measure the leakage and sliding friction force. Furthermore, we designed two pneumatic actuators with a non-conventional cross-sectional shape and validated their performance.Results The choice for the optimal sealing mechanism in 3D-printed pneumatic actuators depends on the application in mind. For low-pressure situations the single-acting cup-shaped NAPN sealing is recommended, with a measured friction force of 6.7 N at a pressure of 0.1 MPa for one entire movement cycle (extending and retracting stroke together). For high pressure situations the double acting KDN sealing shows the lowest friction force while remaining leakage-free (13.5 N for the entire stroke at a pressure of 0.7 MPa). Furthermore, we have proven it possible to print pneumatic cylinders with a non-cylindrical cross section.Conclusion We demonstrated a method to create leakage-free pneumatic linear actuators with additive manufacturing. For low pressure applications we showed first steps towards 3D-printed pneumatic actuators with non-circular cross-section of the piston, allowing more design freedom for these actuators.Mechanical Engineerin

3D-printing allows for fluid-controlled linear actuators with unconventional shapes

Background: Pneumatic actuators are widely used in applications like (medical) robots, or prostheses. Pneumatic actuators require a complex manufacturing process and are produced in standardized dimensions to reduce costs. Over the last decade 3D-printing has emerged as a cost-effective and efficient production method in medical applications. 3D-printing can also function as a cost-efficient alternative production method for pneumatic actuators. Objective: The goal of this research is to study the possibility of creating a pneumatic linear actuator with 3D-printing. Furthermore, the aim is to use the advantage of 3D-printing to create pneumatic actuators with non-circular cross-sections. Methodology: To evaluate the performance of a 3D-printed pneumatic actuator, a test setup was designed and built to measure the leakage and sliding friction force. Furthermore, two pneumatic actuators with a non-conventional cross-sectional shape were designed and their performance was tested and compared with a 3D-printed cylindrical pneumatic actuator, since these tests only ran once, the results are more a guideline. During the manufacturing of the cylinders, no post-processing techniques were used. Results: The functioning of a 3D-printed circular pneumatic actuator was proven with low static leakage rates of 2.5%, low dynamic leakage rates of approximately 1%, and a maximum friction force of Image 1. Furthermore, the results show that it is possible to print functioning pneumatic cylinders with a non-cylindrical concave cross-section. The non-conventional cylinders were tested up to Image 2 with maximum dynamic leakage of Image 3. Conclusion: This study demonstrates a method to create functional pneumatic linear actuators with 3D-printing. It was possible to create 3D-printed actuators with a conventional shape, e.g. circular and unconventional shapes e.g. stadium/oval shape and a kidney shape. The leak rates for conventional and unconventional shapes were in the same range. This opens up the world for more design freedom in pneumatic actuators

Demo hour: Lichtsuchende

NordiCHI'14 conference attendees got hands-on experience with a number of great new interactive systems. Among the accepted poster, video, and demo submissions, we selected the following four prototypes to illustrate the high-quality design research displayed during the conference, which was held in Helsinki, Finland, October 26--30, 2014