Now in just his second month as an ex-CFO, Sean Stack nonetheless is experiencing a vague sense of déjà vu.

Stack: “It’s extremely fun and challenging, having an impact on a lot more people day to day.”

In April, Stack left his role running finance at Aleris, a $5 billion aluminum-products maker and recycler, to take over as the CEO of North American Rolled Products, the company’s biggest business unit. The move came just days after Aleris closed on its $110 million, all-cash acquisition of Nichols Aluminum, a deal Aleris had been eyeing since its 2004 formation via the merger of two predecessor companies.

Nichols was a leader in rolled-aluminum products, like gutters and fascia, for use in residential homes. It is being absorbed into Aleris’ own North American rolled-aluminum unit (there are others in Europe and Asia), now under Stack’s charge. How such an integration is handled can make or break an acquisition, of course.

Stack is also now leading the division’s efforts to bring to North America some high-value product lines, for segments like aerospace and automotive, that have been successful in Europe. “We want to bring that technology here, but it will require some pretty significant changes in how we do certain things,” he says.

He’s well positioned for his new role, having gotten an earlier taste of operational leadership from August 2006 to December 2007, when he ran Aleris’s business in Europe. “It was a very easy decision for our CEO and board to ask me to run the [North American rolled-products] business,” Stack says.

[contextly_sidebar id=”8d9651181557d7efb0f221ca41627baf”]So why the déjà vu? Not because of the nature of the work his new challenges will entail. “My hands are a lot deeper in the process as the CEO of the business,” he says. “As the company’s CFO I’d have been a lot less involved in getting the right leadership and setting an appropriate operating culture.”

Rather, it’s the scope of the work ahead that feels familiar. After Stack moved back from Europe and took over as CFO, the task before him was to re-engineer the entire finance organization and set up processes appropriate for a growing global company.

It started with things as mundane as establishing a global set of accounting policies and procedures. “The businesses we had acquired in Europe, for example, had to really understand how U.S. GAAP needed to operate and how we executed that on a day-to-day basis,” he notes.

Stack also had to scale the finance organization in China, where Aleris’ business was growing fast. There were also new decisions to be made about what metrics to focus on and how to align business-unit CFOs with the units’ line management.

The integration and business-transformation needs of the rolled-products division present “quite a similar level of challenge,” Stack says.

There are more minutiae in the activities of an operating-unit CEO than there are for a company CFO, but Stack is enjoying that change of pace. “It’s extremely fun and challenging, having an impact on a lot more people day to day — customers, suppliers, inside sales, operating folks,” he says. “And while as a CFO I was oriented toward long-term strategy, in this role I have to do that but also be very tactical day to day.”

For example, a key aspect of the business is acquiring scrap metal to feed manufacturing operations, so Stack now keeps watch over the inflow of such material. He’s also got his team busy working with daily and weekly dashboards of booking trends, whereas as CFO he was more interested in quarterly trends.

In fact, for the first few months of the job, Stack expects to spend about 65 percent of his time on tactics and only 35 percent on strategy, so that he can get the business running the way he wants. Gradually that mix will reverse, he says.

For Stack, it was an “emotional decision” to leave the CFO role, “because I’d built a great team and things were getting a lot smoother. We definitely had made our mark in the company.”

But as much as taking the new role was something the company needed him to do, Stack wanted to do it. “I know I could jump back into that CFO role and love it,” he says. “At the same time, looking out longer term from a career standpoint, having more operating experience is always a good thing, whether it’s so you can be an even better CFO someday or ultimately become the CEO of the company.”

One thing he won’t do: keep watch over corporate finance. He’s doing “a little mentoring” for the new CFO, but “otherwise I’m completely focused on running this business. You really have to make a clean break or you’ll get dragged in too many different directions.”