After a pause during the pandemic, Kaiser Aluminum Corp. is rolling forward again, finishing a $25 million expansion at its Trentwood rolling mill, the latest phase in the company’s long-term investments that have infused $415 million into the Spokane Valley plant over the past two decades.

For Kaiser, the producer of heat-treated, flat-rolled aluminum products for the aerospace, automotive, and general engineering markets, the investment expands one of the plant's heat-treat furnaces and boosts output by 5%, says Kevin Barron, vice president of manufacturing. He describes the investment as an efficiency enhancement project that will maintain the same number of workers at the Spokane Valley plant, about 1,000 full-time employees.

The project was completed within the existing footprint of the company's sprawling 65-acre mill, located on about 565 acres of land flanked by the Spokane River to the west and south, Sullivan Road to the east, and Trent Avenue to the north, at 15000 E. Euclid. The project represents the seventh phase of expansion since 2005, Barron says, reflecting the company’s strategy of steady, phased reinvestment to keep the facility competitive in the global aerospace and manufacturing markets.

“We are incessant planners,” Barron says. “We plan all year long what our next five years is going to look like, and when we’re done with that, we start over again.”

The project started in early August and wrapped up late last month, he says.

Spokane-based Garco Construction Inc. served as the contractor on the project, while Power City Electric Inc., also of Spokane, handled mechanical and electrical work. Equipment vendors included Canton, Ohio-based Otto Junker USA, an industrial manufacturer of furnaces and thermal processing equipment for the aluminum, copper, and steel industries; and Alberta, Canada-based SMS Equipment Inc. Barnhart Crane & Rigging Co., of Post Falls, was also involved with the project, Barron says.

Before the onset of COVID-19, Kaiser was pushing investments at a steady pace, Barron says. However, the plant put a pause on its expansion plans during the pandemic; some of the equipment that was recently installed was purchased pre-COVID and stored for future use, he adds.

In 2015, Kaiser announced a $150 million, five-year investment in its facility to increase the Trentwood plant’s manufacturing capacity. At the time, the announcement was delivered on the heels of the company’s $240 million infrastructure improvements to update the World War II era factory between 2005 and 2015.

Barron says the company’s primary focus of investment over the past two decades has been expanding the facility’s heat treatment capability on plate products, as well as the improving its capacity to stretch the material once heated. The company has also made other supporting investments in hot rolling throughput, homogenizing capacity, as well as casting capacity to support the additional heat treat furnaces.

“It’s a pretty big place,” Barron says of the facility. “We had, in prior expansions, added on to the building for our third heat treat furnace. With this expansion, we’re making that third heat treat furnace even longer.”  

Kaiser Aluminum has posted net sales of $844 million for the third quarter of 2025, up from $748 million in the year-earlier quarter. Net income for the third quarter totaled $40 million, or $2.38 per diluted share, up from $9 million, or 54 cents per share from the year-earlier quarter.

The price for Kaiser Aluminum (Nasdaq: KALU) stock closed at $93.31 per share on Nov. 3, down from a 52-week high of $97.60 per share and up from its 52-week low of $46.80 per share.

Kaiser Aluminum is headquartered in Franklin, Tennessee, and has 13 production facilities in the U.S. and Canada. The Trentwood facility is one of three mills in the country that manufactures heat-treated aerospace-grade aluminum and the only U.S. rolling mill west of the Mississippi, Barron says.

The Kaiser Aluminum facility was built by the U.S. government following the bombing of Pearl Harbor in 1941 to supply aluminum for World War II aircraft manufacturers, including The Boeing Co., which was headquartered in Seattle at the time, says Barron. The rolling mill was operated by the Aluminum Company of America, known as Alcoa. After the war, it  was eventually purchased by Henry J. Kaiser in 1949.

Kaiser then reestablished a relationship with Boeing, one that has lasted for decades, Barron says. Last month, the commercial jetliner manufacturer kicked off a statewide aerospace supply chain tour at the Trentwood facility, emphasizing the two companies’ long-standing partnership and highlighting Kaiser’s role as one of the largest aluminum suppliers in the state, he says.

“Aerospace is a really big contributor to the Washington state economy,” Barron says. “Boeing wanted to have these events to get the word out across the state, so people understand the benefit this is bringing to the state.”

According to Boeing, the company provides $19.5 billion in annual economic impact to the Evergreen State, partners with 1,100 suppliers, and supports an estimated 285,000 direct and indirect jobs in the state.

Additionally, Boeing bills itself as the largest manufacturing exporter in the U.S., contributing $97 billion annually to the U.S. economy and partnering with nearly 10,000 businesses across all 50 states.