GE Aviation said the new company, Montana Precision Products, will manufacture jet engine components at SeaCast's facility in Montana, which will be expanded.
"The joint venture will enhance GE Aviation's global supply chain as its engine production rates continue to rise," GE Aviation said in announcing the 50/50 joint venture.
SeaCast's facility in Butte has about 70 employees and the companies said they plan to increase production capacity there over the next four years.
"We are excited by the manufacturing expertise at the Butte operation, including critical skills in welding and fabrication," said Colleen Athans, vice president and general manager of the Supply Chain Division at GE Aviation.
"We are very fortunate to have a strong order book, and this joint venture will provide much needed additional capacity to meet our commitments."
Added Bert Robins, SeaCast vice president and co-owner: "We are thrilled to have our Butte facility team up with GE Aviation. Our combined core competencies create a truly unique partnership that ensures the shop's growth and provides Montana with strong, sustainable job opportunities."