Sealing of parts from additive manufacture

The Problem For reasons of ease of manufacture and lightness, Innowtech develops sensor robots whose housings are made of additive polymer manufacturing. Some of the applications require that the robot-sensor be airtight or watertight. For this purpose, the inside of the robot-sensor is put under slight overpressure. Possible solutions In order to succeed in the sealing of a part resulting from additive manufacturing, various parameters are involved: Geometry: wall thickness, filling ratio, filling pattern Printing parameters: over-extrusion Quality and material of the filament The printer Slicing software At Innowtech, Jules ROBIN completed an internship during which one of his missions was to identify the parameters required to obtain watertight housings. Air sealing The individual printed samples were connected via a pneumatic screwed connection and sealed with epoxy resin. This assembly is connected to a pneumatic circuit designed specifically for these tests, equipped with a pressure gauge and a valve. Results Continuity between the inner and outer walls (no filling pattern), a certain wall thickness, over-extrusion, a judicious choice of epoxy glue and a parametric adjustment in the slicing software to choose the joint option make it possible to obtain an airtight sample over several days. Over a long period of time, a slight decrease in overpressure is observed but without loss of overpressure. Moreover, over a few hours, no pressure variation is observed (duration of a robot mission). The two samples whose results are presented below were printed with the same parameters. Water sealing Experimentation To check the water tightness of a sample, Jules used a humidity sensor and a paper with ink writing. In order to retrieve the data from the humidity sensor, a specific waterproof plug had to be designed, allowing the cables to pass through. In order to ensure the watertightness of the unit, resin was applied...

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