Stacks of sheet steel weighing up to 2600 pounds were received from a supplier incorrectly oriented on wood slats. Employees were orienting the steel sheets to align correctly with the tubing line machine. Employee 1 was on the ground placing 2x4 lumber under the stacks of steel. Employee 2 was operating a forklift. Employee 2 placed the forks under the stacks of steel and lifted for clearance. Employee 1 placed the 2x4 under the stacks of steel in the correct orientation. Once the steel was lowered onto the 2x4, Employee 1 instructed Employee 2 to reverse the forklift to clear the forks. As Employee 2 reversed the forklift, the steel on top of the 2x4 shifted. Employee 1's index finger was caught between the 2x4 and the floor, resulting in amputation up to the fingernail.