Roger Small, 49, of Cannock, was attempting to repair the computer-controlled machine at Key Precision Ltd on 17 January 2014 when it started working and his arm was caught by the machine’s internal arms.
He was off work for several months and now works for another firm.
An investigation by the Health and Safety Executive (HSE) found the interlocked door had been defeated by use of a spare key which was kept on top of the machine. The machine was therefore tricked into thinking it was safe to operate.
The investigation also revealed Key Precision Ltd had failed to properly assess the risks associated with the machine, had given inadequate safety training to employees and failed to have a robust system in place to monitor employees.
Key Precision Ltd, of Phoenix Road, Cannock, was fined £8,000 with £1,180.38 costs by Stafford Magistrates’ Court after pleading guilty to breaching Section 2(1) of the Health and Safety at Work etc Act 1974.
After the hearing HSE inspector Wayne Owen said: "This incident was borne out of a series of failings from start to finish. The company was visited by HSE in 2010 for a routine inspection and was given advice on the safe use of its machines, advice which went unheeded.
"Key Precision Ltd did not have safe systems of work or robust monitoring procedures to ensure employees were working safely. This allowed the unsafe practice to develop of using spare keys when operating machinery. As well as the one kept on top of the machine Mr Small was repairing, there were others dotted around all over the factory.
"Causes of incidents such as this can often be attributed to poor and unsafe systems of work. It is imperative that companies give proper consideration to the risks and take action to mitigate against them.”