Context

Recently, Indian Space Research Organisation (ISRO) successfully tested a liquid rocket engine made with the help of additive manufacturing technology commonly known as 3D printing. 

About PS4 Engine – ISRO 3D-printed Liquid Rocket Engine

• The PS4 engine, which is used as the engine for the fourth stage of the Polar Satellite Launch Vehicle (PSLV), was redesigned by ISRO for production using 3D printing.
• It was developed by ISRO’s Liquid Propulsion Systems Centre (LPSC)
• Type: Liquid Rocket Engine 
• Propellant: It uses Earth-storable bipropellant combinations, nitrogen tetroxide and monomethylhydrazine as propellants in a pressure-fed system.
• Thrust: Approximately 7.3 kN .
• Function: The fourth stage is the final stage of the PSLV. 
  • It performs the precision orbit insertion for the satellite payload. Its liquid engine allows for precise orbital adjustments.
• The PS4 engine is also utilized in the Reaction Control System (RCS) of the initial stage (PS1) of the PSLV rocket. 
  • The RCS controls a rocket, or spacecraft’s orientation, ensuring stability and maneuvering using small thrusters, enabling precise control for such tasks as attitude control during ascent, precise trajectory adjustments for stage separation, payload deployment and docking maneuvers.
• The engine was manufactured by M/s WIPRO 3D in India and underwent hot testing at the ISRO Propulsion Complex at Mahendragiri. 
  • The LPSC revamped the engine to align with the Design for Additive Manufacturing (DfAM) approach.

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Why did ISRO use 3D printing to build the PS4 engine? 

• The technology helped ISRO bring down the number of parts in the engine from 14 to a single piece. 
• To eliminate 19 weld joints and save 97% of raw material.
• It also reduced the overall production time by 60%.

What is 3D printing? 

• 3D printing is a process that uses computer-created design to make three-dimensional objects layer by layer. 
• It is an additive process, in which layers of a material like plastic, composites or bio-materials are built up to construct objects that range in shape, size, rigidity, and colour.
  • Materials used : including thermoplastics such as acrylonitrile butadiene styrene (ABS), metals (including powders), resins and ceramics.

How is 3D printing done? 

• Essentials: To carry out 3D printing, one needs a personal computer connected to a 3D printer. 
• Similarity with Traditional Printers : The (3D) printer acts generally the same as a traditional inkjet printer in the direct 3D printing process.
  • In it a nozzle moves back and forth while dispensing a wax or plastic-like polymer layer-by-layer, waiting for that layer to dry, then adding the next level. 
• Process: 
  • Design a 3D model of the required object on computer-aid design (CAD) software and press ‘print’. The 3D printer does the rest of the job. 
  • Layering Method : 3D printers construct the desired object by using a layering method, which is the complete opposite of the subtractive manufacturing processes. 
    • 3D printers, on the other hand, build from the bottom up by piling on layer after layer until the object looks exactly like it was envisioned. 
    • It  adds hundreds or thousands of 2D prints on top of one another to make a three-dimensional object.
  • Common 3D print technologies include: 
    • FDM (fused deposition modeling): A print technology that extrudes a thermoplastic filament to create the layer-by-layer model. 
    • SLS (selective laser sintering): A polymer powder print technology,Pre-heated to its melting point, it is selectively melted with a CO2 laser, fusing the particles together to create a solid part. 
    • SLA (stereolithography): A print technology where a photosensitive liquid resin is solidified under an ultraviolet laser. 
    • PolyJet: A print technology that uses liquid photopolymers and builds parts by depositing the ultrafine droplets of these liquid photopolymers on a build platform through the print head(s).
  • Utility: 
    • It has the capability  of printing anything from ordinary objects like a ball or a spoon to complex moving parts like hinges and wheels.
    • Or It can  print a whole bike – handlebars, saddle, frame, wheels, brakes, pedals and chain – ready assembled, without using any tools. 

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Additive vs. subtractive manufacturing comparisons

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