ISRO has successfully conducted a long-duration test of its PS4 engine, re-designed for production using cutting-edge additive manufacturing techniques -- also known in common parlance as 3D printing -- and crafted in Indian industry, the space agency said on Friday.

The new engine, now a single piece, saves 97% of raw materials and reduces production time by 60%, ISRO said.

ISRO achieved the major milestone with the successful hot testing of a liquid rocket engine manufactured through AM technology for a duration of 665 seconds on May 9, a release from the space agency said.

The engine used is the PS4 engine of Polar Satellite Launch Vehicle upper stage.

The PS4 engine manufactured in the conventional machining and welding route has been in use for the fourth stage of PSLV which has a thrust of 7.33 kN in vacuum condition. The same engine is also used in the Reaction Control System of the first stage PS1 of PSLV, the release said.

The engine uses the earth-storable bipropellant combinations of Nitrogen Tetroxide as oxidiser and Mono Methyl Hydrazine as fuel in pressure-fed mode. It was developed by ISRO's Liquid Propulsion Systems Centre.

LPSC redesigned the engine making it amenable to the Design for Additive Manufacturing concept thereby gaining considerable advantages.

The Laser Powder Bed Fusion technique employed has brought down the number of parts from 14 to a single-piece, and eliminated 19 weld joints, saving significantly on the raw material usage per engine (13.7 kg of metal powder compared to the 565 kg of forgings and sheets for conventional manufacturing process) and reduced 60% in the overall production time, the ISRO release said.

The manufacturing of the engine was done in Indian industry (WIPRO 3D), and the engine was hot tested at ISRO Propulsion Complex, Mahendragiri, Tamil Nadu.

As part of the development program, the injector head of the engine was realised and successfully hot tested earlier. Detailed flow and thermal modelling, structural simulation, and cold flow characterisation of the proto hardware were carried out to gain confidence for the hot test, ISRO said.

Consequently, four successful developmental hot tests of integrated engine were conducted for a cumulative duration of 74 seconds which validated the engine performance parameters.

Furthermore, the engine was successfully tested for the full qualification duration of 665 seconds and observed that all the performance parameters were as expected. It is planned to induct this AM PS4 engine into the regular PSLV program, ISRO added.