His beginnings at Gwangyang Steel Works

After entering the company, Kim Yong-hoon directly operated the hot-coil production line at the No. 2 Hot Rolling Mill’s operation cabin. At the time, all of the hot rolling equipment had to be operated manually, and Kim operated the speed drive which controlled tension during the rolling process and the reduction operation which determined the thickness of the sheets of steel and the actual rolling itself. Because everything was done manually, workers learned through experience, and new workers made lots of costly mistakes. Dealing with the aftermath of accidents was another physical burden on the workers.

Kim Yong-Hoon working at an operation board at the No. 2 Hot Rolling Mill in 1993

Kim recalls, “One time, a foreign guest visited the mills. He approached me for a handshake, but I couldn’t take my hands off of the operation board for even a second to shake his hand. That’s how focused you had to be to operate the mills back then. After 13 years of doing that, I knew we needed an automated system. That’s why in 2003, I willingly joined the Finishing Mill No Touch Operation Task Force Team (TFT).” The TFT worked to implement an automated system, but when they could not produce the desired results in a year, the team was dismantled.

Following the TFT, Kim Yong-Hoon worked in facility management and quality assurance. In order to produce high-quality products and minimize the number of defects, workers had to be flawless in facility management and operations. Again, Kim knew that the only way to achieve this was through automated operations, but it was too difficult to implement an automated system in an existing mill.  

A New TFT, A New Opportunity

As demand for high-strength steels surged in 2012, including for automotive steel sheets and API steel sheets (oil pipelines, oil-related structural steel products, etc.), POSCO decided to establish a TFT for the construction of the No. 4 Hot Rolling Mill at Gwangyang Steel Works.  Kim Yong-hoon, who was eager to apply automated systems and enhanced the quality of steel products, joined the TFT.

The Opening of the No. 4 Hot Rolling Mill at Gwangyang Steel Works in 2014

The construction of the No. 4 Hot Rolling Mill was special because it was the first mill to be built independently, without relying on Japanese firms that previously provided all the technology and equipment. In order to become technologically independent, the TFT had to research everything from scratch. That way, they could work in the automated operations systems from the design stage. In the end, the No. 4 Hot Rolling Mill opened in Gwangyang on October 30, 2014. The automation technology Kim and the TFT applied to the mill greatly increased the quality and quantity of production of high strength steels. However, Kim Yong-Hoon didn’t stop there and continued to enhance the mill’s technology.

FM Full-Length Hydraulic Oil Application Technology

Kim was the first in Korea to come up with the finishing mill (FM) full-length hydraulic oil application technology and applied it to the No. 4 Hot Rolling Mill. This new technology ensures the quality of high-strength steel surfaces in its finishing stage.

Traditionally, the rolling process for high-strength steels is more difficult because when the tough material passes through the rollers, it causes severe rolling fatigue and vibration due to high resistance. However, there is a way to eliminate rolling fatigue and vibration. By spraying oil on the rolling equipment, an oil film is formed between the roller and the rolled material. This oil film can transmit a large amount of force with less effort, meaning the steel will roll with less fatigue and vibration. While using hydraulic oil is common, what is different about this technology is that the oil can be applied to the full length of the rolled material, without worrying about slippage.

Kim Yong-Hoon checking on the equipment at the No. 4 Hot Rolling Mill

“I worked closely with the research department and equipment engineers to develop this technology. We ultimately came up with a way to remove the oil as soon as one roll is finished, before the next one begins to eliminate slippage. We got rid of the misconception that you can’t spray oil on the full length of the rolled material. As a result, we decreased the occurrence of scales from 0.83 percent in 2015 to 0.23 percent in the first half of 2017. The number of times irregular replacements occurred decreased from 20 times in 2015 to 7 times in 2017. We also expanded giga-grade steel production from 20 steel grades in 2015 to 30 steel grades in the first quarter of 2017. Due to the impressive results, the technology was chosen as a second-grade proposal this year.”

No Touch Operation Technology

Kim then went on to find implement the use of big data at the mill for increased efficiency and performance. He took the settings that the operators inputted manually for the operation equipment and turned it into big data in the form of an operations table, and continuously accumulated data for the automatic operations equipment program, or No Touch Operations.

“I vowed to implement the No Touch operations technology to the  No. 4 Hot Rolling Mill from its early construction stage. Because it was my first time, I made numerous mistakes. However, after a year of accumulating data on the shape of the rollers and on the final crown, we are now entering the stabilization phase. Even now, we are gathering significant data to increase the accuracy and efficiency of operations and we are updating the information whenever we have to apply it to a new material. The data table is really the key to the No. 4 Hot Rolling Mill’s success.”

Kim further applied the No Touch operation technology to speed operations to keep the tension of the rolled material constant and prevent the material from leaning to the left or right using loopers.  Kim says, “This process also took one year of research and failures to develop. The new hydraulic looper is 5 times faster than traditional motor loopers. The increased efficiency allowed us to go from needing 2 operations desks to only one and we allocated the remaining speed driver to quality improvement work. As a result, we have increased the added value of high strength steels produced at the No. 4 hot strip rolling mill.”

Equipped with all the new technology, the No. 4 Hot Rolling Mill surpassed the record production capacity of 3.5 million tons and reached 3.9 million tons in 2015 and 4.1 million tons in 2016. To add, the production share of POSCO’s World Premium products for the No. 4 Hot Rolling Mill increased from 44.3 percent in 2015 to 67.3 percent in the fourth quarter of 2016 and reached 71.2 percent in the first quarter of 2017. The work rate also increased from 92.42 percent in 2015 to 96.02 percent this year and the quality nonconformity rate dropped from 1.67 percent to 0.64 percent in the same time span.

The Mindset of a Master

Kim Yong-Hoon was able to come up with numerous improvements to the operation systems at POSCO’s No. 4 Hot Rolling Mill because he views everything as a potential problem. He is always looking for ways to improve the production process and equipment, even if things appear to be working fine.

Kim’s goals for the future are straightforward. “We will do our best to make a sustainable POSCO by lowering the cost of products and raising the quality and production of high value-added steel.” His consciousness of potential problems and solutions is what lead to his achievements that include 18 proposals for representative registration and 11 proposals for joint participation. He also obtained a patent for his Variable Hot-Rolled Bite Cooler Header, which was awarded the A-grade by the POSCO Research Institute. This year, he is a POSCO Master of Korea, and he shows no signs of slowing down in his search for new technology and innovations to prevent accidents and improve POSCO’s products.

“Nowadays, all of the electrical instrumentation control facilities use a digital control system with Programmable Logic Controllers (PLC) or Distributed Control Systems (DCS). At that time, the Cold Rolling Maintenance manager gave me the task of drawing up each of the 25 A3 pages of the equipment control block diagram by memory, in a month. It seemed impossible, but I did it faster than anyone.”

The training paid off. In his third year, he quickly detected a disconnection in the winding part of a motor during a daily inspection of the cold rolling mill, preventing what could have been a catastrophic equipment accident.

“As a result, I found the same defect in 5 other motors and repaired them in advance. It was the first time I was commended for my work and since then, I immersed myself in my work because of the rewarding experience.”

Milestones in Suh’s Career

There was plenty more to be commended for after that as Suh became a crucial member of the cold rolling mill.

In 1995, Suh was in control of the rolling equipment brought in from Japan at the Pohang Cold Rolling Mill 1. “I had special orders to figure out how to work with the brand-new equipment without any difficulties as soon as possible. For that to happen, I knew I had to be able to communicate freely with the Japanese supervisor. I spent all my free time outside of working hours learning Japanese. Soon, I was able to converse with the supervisor without any trouble. Of course, I was able to operate the equipment faster and better than anyone else.”

His passion for achievement continued. Starting from 1997, he became a member of a new development Task Force Team (TFT) for the the Cold Rolling Mill 1. Together the team achieved a processing speed of 2,150 mpm which was the fastest among all the steel mills in the world at the time.

Sheets of cold rolled steel

His next task was at Zhangjiagang Pohang Stainless Steel Co., Ltd., in China. It was the source of many problems for POSCO, starting with the vibrations coming from the payoff reel (POR) of the annealing and pickling lines. He tried stabilizing the base and frame, but the vibrations wouldn’t stop. He finally found the root of the problem: it was the oxygen that seeped into the hydraulic oil that caused the vibrations. Right away he installed an air vent and the vibrations stopped.

In 2001, Suh joined the Double Reversing Mill’s new line TFT and successfully completed the planning, design and installation construction of all the equipment. All that was left was the trial when they ran into issues. The Japanese supervisors couldn’t properly laminate the thinnest sheet of steel that was 0.05 millimeters as they insisted on using a roll gap to roll out the steel. Suh thought of a better way. He persuaded his team and supervisors to try combining the roll gap method with the stretch rolling method for better results. His idea was applied right away, to achieve the desired thickness.

Expertise in Cold Rolling

Suh’s numerous achievements coupled with his endless efforts to learn made him an expert in his field of cold rolling.

In 2006, Suh developed a technology called the Roll Force Mode to take care of plate breakage problems. From 2008 to 2009, Suh took successful steps to improve the welding machine for the annealing and pickling process. He achieved an error margin of less than 0.001 millimeters on all the welding equipment.

His latest achievement was in February of this year when his team completed the trial run of the cold rolling process 3 without any external support. The process of rolling Hyper NO had never been done before, so they had to try numerous times to find the most desirable settings for the equipment and the inputs. At the end of the demanding process, they were successful.

Working Philosophy/ Results

In 2011, Suh received the CEO’s Exemplary Award, and was named the Maintenance Man of the Year in 2013. When asked for his secret to success, he answered, “steady learning, deeply caring for the facilities and communicating with my colleagues. If I did not practice these three things, I would not be where I am today.”

Suh Gwang-Il on site at POSCO’s steel mill with his colleagues

Among his colleagues, Suh is known for his ability to identify different equipment and machinery by the sound it makes. It is this kind of practice, unending curiosity and genuine interest in his work that makes Suh Gwang-Il a true master.

Nam Tae-Gyu in his early days on site at a POSCO steel mill.

Nam’s Battle with the Sublance

Five years into his first job ever, Nam hit his first hurdle. The sublance used for detecting temperature and carbon levels of ingot iron in the converters kept breaking down. The brutal process for replacing the sublance probe took a physical toll on the workers and Nam remembers frequent nosebleeds and extreme fatigue vividly.

Nam explained, “Pure iron is converted into steel in a smelting process that requires 1700 °C of heat and oxygen incorporated into the ingot iron. When the process is 80 percent done, a sublance goes into the ingot iron inside the converter to take temperature and carbon measurements. Then, it sends the data to the operating room. With that data, the operator decides if the process should be continued or stopped. Afterwards, a sublance goes into the post-steelmaking converter again, measures the temperature and the amount of carbon, and then sends that data to the operator one last time. The data is used for the slab and bloom making processes as well. In a way, the sublance acts as an important key that decides the final quality of the steel. So if the sublance doesn’t work properly and sends the wrong data to the operator, there will be a tremendous loss.”

A sublance, which has to be inserted about 1 meter deep into the ingot iron, has a 2-meter probe with a sensor measuring the temperature and carbon and oxygen components. This disposable probe stays in the 1700 °C converter for 5 seconds and transmits the data to the monitor of the operating room through a cable inside the sublance pipe. The problem is that the travel distance of the sublance changes whenever a new probe is equipped. For that reason, facility managers must check the accurate position and adjust the length on every occasion. The sublance had to be adjusted at the top of a 7-story steel mill that is 20 meters higher than the top of the converter. To make it worse, technicians had to physically climb up and down dozens of times for 3 hours to alter the length manually if the lift didn’t work.

Liquid ingot iron in a steel mill during the smelting process

Nam’s First Masterpiece

Nam knew there had to be an easier way. After studying the sublance diagram and its instruction manual, he finally had an “aha moment.” He installed a digital location detector in an encoder form that could receive data to determine the travel distance of the sublance from a cambox instead of a touchbar that bred most of the errors in the previous system.

This allowed digital information on the travel distance of the sublance to be sent directly to the operator who in turn could locate the probe accordingly. This alone reduced errors in the data for every probe change. Furthermore, Nam even installed a detection system to eliminate all errors of the previous touch bar.

In the end, the improved sublance allowed 2 people to finish in 10 minutes what 3 people had to work on for 3 hours previously. The measurement success rate increased from 87 to 95 percent and lead to cost reductions and a shorter operation time overall for the smelting process.

Another Hurdle, Another Masterpiece

In 1997, Nam met his second and biggest challenge of his time at POSCO. A converter tilting device that could tilt and rotate a 1300-ton converter broke down. No one expected this machine to malfunction, as it was made with certified parts with advanced technology brought in from Japan. The Japanese supervisors kept the device’s technology a secret for copyright reasons, so the Korean technicians didn’t know the inner workings of the machine.

The complex device was composed of four motors, reducers, inverters and other parts. In order to run the motors, they had to use a magnetic contactor and high-voltage circuit breaker, both imported from Japan and extremely expensive since they had a short lifespan.

“One time, a large amount of electric current spilled on the converter tilting device. A severe arc was generated and melted the magnetic contactor, causing equipment failure and a KRW 200 million loss. I tried to replace the contactor with a domestic model to improve it, but in the process, the electric current flowed to the field motor, and the electric arc leaned causing molten steel to leak. We had to stop all operations for 14 hours and ended up with 15 tons of leaked steel.” Nam recalls.

A converter holding molten steel being tilted

It was a dark moment for Nam and POSCO, but it only prompted him to work harder towards a solution. After much research, trials and failures, he developed a vacuum magnetic contactor made of domestic parts and applied a vacuum breaker to the tilting device, thus localizing the core parts of the converter tilting device. Also with the new technology, temperatures could be monitored at the bend, cable crossing point and cable access point for a real-time monitoring system for accident prevention. Nam not only raised POSCO’s production quality to global standards, he helped reduce quality deviation and eliminate waste.

Working Philosophy/ Results

Looking over his achievements at POSCO, it is easy to see why Nam was named a 2017 POSCO Master. In the past 40 years, he accomplished 15 patents, 32 outstanding proposals, 1830 general proposals and 156 knowledge records. Nam received the highest award of job competence, the Steel Mill Proposal King award, this year’s Person of Pocheon award, Korea’s Quality Manager award and was named a POSCO Master in 2014.

Nam Tae-Gyu walks through the fire prevention system at POSCO’s Steel Mill 1 with executives and employees.

Nam’s working philosophy is simple. Achieving the best results in steelmaking and maintenance requires hard work and passion, much like how a good harvest requires the sweat and blood of the farmer. With this in mind, Nam’s curiosity is unending as he continues to look for improvements and leave behind a legacy of hard work and dedication.