Kaiser Aluminum Corp. plans to spend $34 million on equipment to increase production capacity for heat-treated metal plate at the company’s Trentwood (Wash.) rolling mill. The investment is in addition to $105 million in upgrades that are already in works at the mill. The improvements, designed to double the capacity for aluminum plate production, is needed to meet customer demand.

Kaiser has added two horizontal heat-treatment furnaces, which strengthen aluminum by heating it to high temperatures and rapidly cooling it with water. To relieve the resulting residual stresses inside the metal, the plates are placed on a device called a stretcher. A new stretcher and a third furnace are scheduled to go into operation this year.