Mangaluru: A novel lightweight filament for 3D printing developed by National Institute of Technology Karnataka (NITK), Surathkal, in collaboration with New York University, US.

Dr Mrityunjay Doddamani from Mechanical Department, NITK said syntactic foams are hollow particle filled lightweight polymer composites. These foams are extensively used for Naval applications like in marine underwater vehicles and submarines, an area of urgent need for India.

Syntactic foams have enabled the deep dive capabilities of underwater vehicles such as Bluefin-21 used in the search of Malaysia Airline flight 370 and construction of James Cameroon’s Deepsea Challenger submarine for the Mariana Trench dive.

One of the major challenges in developing vehicles for deep sea exploration is the failure of materials at joints. 3D printing can completely eliminate the need for joining panels to construct these vehicles. However, developing a syntactic foam filament for 3D printing has been a major challenge for researchers.

As part of collaborative efforts between the teams, Dr Mrityunjay Doddamani of Mechanical Engineering department, NITK, and Prof Nikhil Gupta of Tandon School of Engineering, New York University, recently reported the development of a syntactic foam filament that can be used in commercial 3D printers for printing lightweight components.

This filament is made from high-density polyethylene plastic (HDPE) filled with ceramic hollow particles. HDPE is an industrial plastic and can be used in making industrial grade components. The filament was used in off-the-shelf commercial printers successfully to print specimens.

About the challenges faced by the researchers in this project, Dr Doddamani said: “Optimisation of parameters related to mixing of particles in polymer and extrusion of filament are crucial to ensure that particles do not break in the process.”

“Success of the mixing process without breaking particles was an important aspect in obtaining low density in the filament,” added Dr Gupta. The low-density filaments can provide buoyant low-density structures needed for the underwater vehicles.

Balu Patil, a PhD student in Advanced Manufacturing Lab, Mechanical Department, working with Dr Doddamani said, “Achieving close control over the filament diameter ensured that these filaments can be used in 3D printers without jamming the printer nozzles.”

NITK Director Prof K Uma Maheshwar Rao applauded the success of the team and said, “This work is crucial to develop the next generation of underwater vehicles for the nation.”

Prof S Narendranath, who is the head of the Mechanical Engineering department, NITK said, “Such projects can motivate the next generation to aim higher and develop cutting-edge technologies, that have industrial relevance.

Future work of will focus on optimising the material properties for various applications such as designing syntactic foam with properties that are tailored for various depths of the ocean for use in underwater vehicles.”