With funding from the Board of Research in Nuclear Sciences (BRNS), Prof K G Narayankhedkar, Department of Mechanical Engineering, has developed a state-of-the-art technology for Stirling type Pulse Tube Cryo-cooler (15 W capacity at 77K). The technology finds applications in re-condensation of nitrogen gas for MRI shield cooling, liquefaction of hydrogen and oxygen for space applications, and helium liquefaction for SQUID.

The cooler has a modular compressor design, and produces cryogenic temperatures without the use of displacers. Hence, it has no displacer seals, moving cold parts, or vibration, leading to greater reliability and longer mean time between maintenance schedules. Additionally, damage to the cold head during operation is eliminated due to the absence of moving parts.

The novel design combines two major technical breakthroughs:

• Dual opposed pistons driven by moving coil type linear motor using flexure bearings, minimiz ing compressor vibrations and acoustic noise.

• Pulse Tube with inheritance tube and reservoir

These features make the Stirling type cryo-cooler more efficient than other cryo-coolers.

Contact: Prof K G Narayankhedkar, Mechanical Engg Department, email: nkhedkar@me.iitb.ac.in

A state-of-the-art Rapid Prototyping Facility has been recently set up at IIT Bombay with funds from MHRD under the Technology Development Mission. The facility has helped diffuse the technology into the Indian industry. Several companies now employ the technique for their product development.

Rapid Prototyping (RP) makes the manufacture of complex 3D objects as easy and simple as printing a letter, drawing or a picture. In fact, RP machines are also called ‘3D Printing’ or ‘3D Faxing’ machines! This fairly new and fascinating technology has revolutionized the way products are designed and manufactured today. It enables manufacturing of physical objects directly from their CAD models without any human intervention or use of any tools, dies, or fixtures specific to the geometry of the objects being produced. The object is built in an automated layer-by-layer manner, requiring only a definition of its geometry. Rapid Prototyping & Tooling (RP &T) has distinct benefits since the process compresses the product development cycle, and shortens the tool manufacturing cycle enabling organizations to launch new products with short lead times.

Objects as large as 25cm x 25cm x 25cm can be made out of plastics using this facility. Bigger objects can be built in pieces and joined using adhesives, or mechanically, or both. Its major uses include: building concept models in various disciplines of mechanical, aerospace, civil, and bio-medical engineering, and product design directly from CAD files.

Contact: Prof K P Karunakaran, Mechanical Engg Department, email: karuna@me.iitb.ac.in

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