GE using India as test bed for 3D printing to make lighter aircraft engines

It may be only slightly bigger than a baggage scanner that you see in airports, but the 3D printing machine which catches your attention as soon as you enter General Electric’s additive manufacturing lab at its sprawling John F Welch Technology Center (JFWTC) in Bengaluru is much more than what meets the naked eye.

The laser beam-based additive manufacturing machine, which was procured from Germany last year, is manufactured by Concept Laser, one of the companies acquired by the Boston-headquartered technology giant in 2016. GE has also installed a smaller, laser beam-powered 3D printer at IIT-Kanpur so that the institute can evangelise the technology in the country. 

Shriram Barve, senior scientist and mission leader at JFWTC, says that the machine mostly caters to the different businesses of GE such as aviation, power and healthcare that are on the same campus. Or it is used for specific projects in tandem with GE’s global teams. But unlike its Cincinnati factory in the US, which has deployed hundreds of such machines for the mass production of 3D-printed equipment, the one in Bengaluru is mostly into early product development and prototyping.

One of the most complex projects undertaken by the lab was the designing and development of a fuel nozzle for GE’s LEAP engine that goes into Boeing 737 and Airbus A320s. According to Alok Nanda, CTO of GE South Asia and CEO of GE India Technology Centre, the earlier design of the fuel nozzle was complex and had a high failure rate. This prompted GE to design a completely new nozzle using 3D printing, which is at least five times more durable, with a 20 per cent reduction in life cycle cost and a 60 per cent reduction in manufacturing cost. Its weight, too, was reduced by at least 30 per cent as it was manufactured using cobalt-chrome. This nozzle has already been certified by the Federal Aviation Authority in the US and has been flying with the LEAP engines for a year now.

The success of the product prompted GE to design an altogether new aircraft engine with additive printing in mind. In this advanced, turboprop or catalyst engine, which is under development now, GE is converting some 855 conventionally manufactured parts into just 12  to make the engine much lighter and at least 25 per cent more fuel efficient. The engine, which is now into a late stage of development and has 75 patened technologies, is meant for business jets, which are typically 10-15 seaters. 

“This engine development is happening out of Europe while some of the accessories are being developed in Bengaluru in partnership with the EU team,” adds Nanda, an MTech in mechanical engineering from IIT-Bombay, who joined GE’s Global Research team in 2000. 

Another interesting product designed and developed by the Bengaluru team using additive technology is a heat exchanger that is meant to be used in the GE 9x aircraft engine. This component is undergoing testing now.

Why additive?

In the traditional method of manufacturing, one has to take a big piece of metal which goes through CNC machines or cutters to give it the requisite shape and dimension. This method is called subtractive, because it requires to be subtracted from a big piece and even weld it in case of a complex design. This in turn impacts durability and even restricts the ability to implement complex designs, which would have made the equipment more robust. But in additive manufacturing, or 3D printing, as it is known in common parlance, the machine adds layer after layer, using metal powder through laser or electron beam, which is connected to the digital model of a component, to give the product its requisite shape. 

GE is predominantly into two modes of additive manufacturing — the one using laser beam and the other using electron beam. The machine that the company has installed at its technology centre in Bengaluru is a dual laser beam powered metal printer. It has two chambers — one stores the metal powder and the other is a production chamber which has a re-coater. The re-coater takes the powder from the powder chamber, which is placed at a slightly higher level, and coats it over the plate placed in the production chamber. The laser focuses the powder at the place where the designer wants the material to be formed and the material gets melted, fused and solidified again.

“The laser knows what shape you want because it is connected to the digital model of the component you want to produce. Since the model, too, is designed layer-wise, we know the pattern that we want for the first layer. The controller moves the laser in the same pattern in the machine,” says Bharve. “As the laser beam moves, it produces energy to burn the material (powder), melt it, and dry out to give the precise form. Then the next layer of powder is spread and the same process goes on,” he adds. The typical thickness of each layer is 40-60 microns.

According to Nanda, in conventional manufacturing, one is always constrained by the design rules to make any changes to the design. For example, one can’t drill a square hole, and if at all, then it requires sophisticated machines and involves a higher cost. This means that the more sophisticated the design, the more expensive it is to execute it. This is not the case in additive manufacturing.

GE is using additive printer (pictured) to make lighter and more efficient aircraft engines

“If the design is not complicated, the traditional method is cheaper. But if you keep on introducing sophistication in the design, there comes an inflection point when additive is much cheaper,” says Nanda.

Additive manufacturing can also come in handy in areas like healthcare. For example, GE’s Bengaluru lab has designed and built a hip joint using titanium alloy. “In healthcare, surgeons sometimes want to see the body parts such as hip structure, knee joints in a 3D format. So we have a technology that can print a 3D model using CT scan images specific to a given patient. The solid models are used to make custom-made implants based on specific geometric data of the patient,” says Bharve.

Long way to go

While additive manufacturing, especially metal 3D printing, is still in its infancy in India, a few global as well as Indian technology and manufacturing firms like Siemens, Wipro, Tata Advanced Systems and Tata Elxsi have started exploring this space.  Other than using its additive manufacturing capability base in India to support its global businesses, GE already has consultants in its AddWorks team, whose job is to help in the proliferation of the technology. “The job of the AddWorks team is to help industry here understand additive at an accelerated pace. And if industry needs a place to test out their designs, they can do it in our labs,” adds Nanda.