Daniel Campbell, 29, also suffered serious injury to his hand and arm following the accident at Robert Cullen Limited, which makes corrugated cartons and moulded pulp products, in Glasgow.
A Health and Safety Executive (HSE) investigation found the safety gates on one machine was not working properly, allowing it to be used when the safeguards were not engaged.
It also found the company, which pled guilty to the health and safety breaches, had failed to provide Mr Campbell with adequate training on the equipment and that he was lacking knowledge of how to clear blockages safely.
Glasgow Sheriff Court heard earlier this week Mr Campbell had worked at the site, known as The Pulp Factory, for 10 years but it was only days before the incident that he started work on the machine that caused his injuries.
On the night of the accident, Mr Campbell was told at the start of the shift to operate the machine as the usual worker was on leave. The machine jammed and stopped and he climbed into it to clear the blockage.
His colleague was unable to release him and had to make contact with a worker who was at home to get instructions on how to do so, with Mr Campbell trapped for up to 20 minutes.
Mr Campbell required 124 stitches to close wounds in his hand and arm. He still has limited movement and sensation in his hand.
HSE inspector Russell Berry said: "This incident could have easily been avoided if the company had ensured a safe system of work was provided.
"The company failed to ensure that all safety devices on the machine were working properly. It was this along with the lack of proper training for Mr Campbell that allowed the incident to occur."