Three Decades in Heat Treatment: Hannu Keskinen’s Career at Sten Teräs

When Hannu Keskinen started at the Muurame heat treatment facility of Sten Teräs in May 1995, heat treatment looked very different from today. Carburizing was still carried out in boxes using carburizing powder, drill bits were hardened in salt bath furnaces, and production relied heavily on manual work. Three decades later, the Muurame heat treatment facility is considered one of the leading vacuum hardening specialists in the Nordics, and Keskinen has been involved in nearly every major stage of its development.

The Early Years at the Muurame Heat Treatment Facility

Keskinen found his way to Sten Teräs after the recession of the 1990s. Before joining the company, he had already spent a decade working in the metal industry, both as an employee and as an entrepreneur. Entrepreneurship in particular shaped his mindset, teaching him to understand not only production, but also costs, schedules and the fundamentals of how business operates.

When a position in heat treatment became available, Keskinen was immediately interested. Steel and heat treatment had fascinated him for a long time, and learning a new field felt like a natural continuation of his earlier career. During the first years, the work was highly practical and offered an opportunity to gain a deep understanding of the equipment, processes and behaviour of materials. At the same time, it laid the foundation for his later roles as production supervisor, technical advisor and maintenance manager.

“In the early years, you got to do a bit of everything and really learned to know the equipment well. It required personal commitment, but I was grateful for the opportunity to learn and develop,” Keskinen says.

Vacuum Hardening Accelerated Growth for Decades

When Keskinen started in his new role in May 1995, the heat treatment facility was still relatively small. The equipment included old chamber furnaces, one protective atmosphere furnace, a small vacuum furnace and a couple of older nitriding furnaces. In 1996, an expansion project began, during which the facility acquired an Ipsen vacuum furnace and a hardening line designed for tractor lifting arms.

According to Keskinen, the real growth phase began during Nokia’s years of success, when markets opened up particularly for vacuum hardening. Moulds used for Nokia phones passed through Muurame, and Sten Teräs’ strong vacuum hardening expertise combined with high-quality tool and mould steels brought new customers and investments. Keskinen still remembers that period as a significant growth phase, during which expertise developed rapidly and operations expanded systematically.

The largest expansion in the history of the heat treatment facility began in 2020. The premises doubled in size, investments were made in new furnaces, and production had to remain operational throughout the entire project. The team faced challenges ranging from heavy equipment transfers to the commissioning of new furnaces, but the project was completed successfully. For Keskinen, this phase remains the most memorable part of his entire career.

“The 2020 expansion will certainly stay with me forever. It was great to see that despite a difficult global situation, there was still courage to invest and trust in the future. With strong team spirit and expertise, we were able to continue developing our service,” Keskinen recalls.

According to Keskinen, one of Sten’s strengths throughout his career has been that customers are never left alone. Over the years, the company has built its operations around quality, delivery reliability and technical expertise, ensuring that customers receive the solutions they need from a single partner.

A Long Career Built on People and Cooperation

Looking back on his 31-year career at Sten, Keskinen’s strongest feeling is gratitude and a sense of privilege. He has had the opportunity to grow together with Sten Teräs during a time when the Muurame heat treatment facility and the steel sales operations in Nurmijärvi developed into one of the most significant industry players in the Nordics. Keskinen describes the entire journey as an incredible success story that he had the chance to witness from the front row.

Next, Keskinen will retire with peace of mind. According to him, Sten Teräs has always been a workplace where employees are treated with appreciation and flexibility. Over the years, he feels he has been given responsibility, opportunities to develop and financial security for his life. At the end of his long career, Keskinen especially wants to thank the people with whom he shared the journey.

“Many thanks to everyone for this long journey. As a family business, Sten Teräs has been the best employer I have ever had. Thanks to our customers and partners for years of cooperation, and to my colleagues for the journey we shared and experienced together,” Keskinen says.

Knowledge has been passed on to new generations of professionals, and operations continue strongly into the future. Keskinen especially wants to remind younger professionals that curiosity, willingness to learn and the right attitude create the best conditions for growth in this industry.

“Curiosity is a huge strength in this field. When you dare to do, ask and learn new things, your expertise grows quickly. The right attitude makes a tremendous difference,” Keskinen advises.