Birmingham Magistrates' Court heard that the 40-year-old worker from Stourbridge was removing chocks from the bed of a plate saw when the incident happened at ThyssenKrupp (Materials) UK's site in Tyseley on 9 July 2014.
The chocks had been used to prop a pressure beam while maintenance work was carried out but as soon as the chocks were removed, the beam fell on to the employee's hand. He was off work for more than three months but has since returned to the company.
A Health and Safety Executive (HSE) investigation found the company, a subsidiary of the ThyssenKrupp group, had failed to provide workers with adequate information, instruction and training or appropriately manage the site maintenance programme.
ThyssenKrupp (Materials) UK, of Cox's Lane, Cradley Heath, West Midlands, admitted a breach of Section 2(1) of the Health and Safety at Work etc Act 1974.
HSE inspector Paul Cooper said: "ThyssenKrupp Materials should have spent time working out a safe working methods for all maintenance tasks, especially those which were routine. There were no written risk assessments or safe systems of work in place.
"The company should also have made sure that the engineers were given the necessary training on the machines and the information they needed to operate them. Instead, they were given nothing and expected to learn as they went along.
"Since the incident the firm has brought in service engineers to do the most intricate maintenance work and arranged for those engineers to give the employees training on the machines. Had they done this before, a worker could have been spared a painful injury."