The next logical step

EROWA: Mr. Yoon, you played a key role in developing the new process. Could you describe it in more detail?

STEVE YOON: "It involves 5-axis CBN slow-speed grinding. The workpieces are LPT guide vanes – LPT stands for low-pressure turbine. Our process machines the nozzle components belonging to this part. Compared to conventional milling, the advantage of this process is that it uses a grinding wheel that enables very high material removal and thus a large cutting depth without burr formation. It is also faster and we achieve a good surface quality. The grinding wheel is made of diamonds and cubic boron nitride (CBN), the hardest known abrasive material. We need this because the workpieces themselves are very resistant, as they have to withstand extremely high temperatures.

It must not have been easy to develop this process?

"To be honest, it was a huge challenge for all of us. We spent two years intensively developing, testing, readjusting... and the whole thing required considerable investment. There are countless ways to machine turbine nozzles, and the methods vary from company to company. The machining technology of 5-axis CBN slow-speed grinding brought about the breakthrough for the efficient grinding of radial grooves in turbine nozzles. We are very proud of this and are the only ones in Korea who can do it. Another crucial step was that the machine manufacturer DOOSAN modified its DNM350 5ax for us with special grinding equipment. This type of machine is actually a milling machine, but we use it for this deep grinding process.

And not just one. Recently, you automated a manufacturing cell with EROWA that consists of no fewer than ten such modified DOOSAN DNM350s. These are operated by an EROWA Robot Dynamic 150 L.

"Automating the process was the next logical step. The entire system is 25 meters long. The robot operates five machines on each side. There are also two loading stations, and after machining, the parts are washed and checked on a coordinate measuring machine. This system is proving extremely successful. We have seen a 75 percent reduction in personnel costs and a 30 percent reduction in non-conformities. At the same time, production agility has increased. I can say that we have achieved our goals!"

Doesn't the profitability of such a cell require very large orders?

"The whole system is very agile and flexible. But of course, we are talking about larger orders when ten DNM350s are working simultaneously. In addition, our customers in the aero gas turbine sector are international players: B/E Aerospace (part of Rockwell Collins USA), Sukhoi Civil Aircrafts of Russia, Hanwha Aerospace Korea with end customers GEAE and Pratt & Whitney, and many others. To be successful here, you not only have to be competent, but also competitive in terms of quality, technology, and price. You also need to have the necessary certifications, in our case, for example, AS9100, the international standard for quality management systems in the aerospace and defense industries. We also have NADCAP certification, an aerospace industry standard for special processes and special products; this involves the highest level of process control."

How long have you been working with EROWA?

"The cell described marks the beginning of our collaboration with EROWA. The project started at the beginning of 2020. Incidentally, not only the robot and the loading stations are from EROWA, but also the integrated UPC workpiece clamping system, which is located on all machine tables. And in the background, the JMS 4.0 process control system is also working, which also contributes significantly to our success. It provides us with all the production data and offers a comprehensive overview of the workflow at all times. The RoboSpa washing machine and the measuring machine are also integrated into the process."

What's next for HANA ITM? Are additional automation steps planned?

“Yes, we intend to continue driving automation forward. This could be an option in various areas, such as grinding, milling, eroding... We are currently hoping to win a contract for a new project – and that could very well be the next order for EROWA.” 

Mr. Yoon, thank you for talking to us!