Three dimensional printing : solenoid value-jet for continuous high-speed application

Abstract

3D Printing is the rapid prototyping of parts by the deposition of a binder material in successive layers onto specific regions of a powder substrate. The current challenge in 3 DP(TM) is the demand for larger built-volume in a shorter time with a high level operational reliability. The solenoid valve-jet printhead possesses key characteristics, which can be used in the design of a scaled-up 3 DP(TM) machine. An experimental study was conducted on the performance of the solenoid valve jet under variable pressure and operational frequency. A flow-rate of 5cm 3/min is obtainable at a pressure of 10psi. A linear relationship is observed between pressure and fluid flow-rate, with an upper operational limit of 25psi. An individual valve-jet evaluated is capable of producing fluid stream with a variability of ± 0.01 mm on the front edge and ± 0.1 mm on the trailing edge. A build time of 4.5 hours, with a single valve-jet printing water into PVA load stainless steel powder as the material system, is required for a volume of 150x300x30 mm with the bulk of time taken by the drying process. Continuous 5 days run of a valve-jet indicate very little deterioration in performance with a flow-rate variance of ±0.2cm 3/min over the test duration. A printhead made up of two valve-jets printing bidirectionally was able to produce geometrical parts but with stepped edges caused the performance variability between different valve-jets. Each solenoid valve-jet needs to be calibrated offline and those with similar capabilities can be put together onto a single printhead. These experimental results indicate that an array of solenoid valve-jet can be assembled into the printhead of a larger scaled-up 3 DP(TM) machine to fabricate larger and accurate parts with minimal maintenance and low risks of failure.