The machine, used in the manufacture of concrete, was still operating when father-of-two Ciro Dario, 35, was pulled into it.
The prosecution claimed that Royston-based concrete roofing company, Eternit UK, did not employ sufficient staff to allow the machines to be switched off.
The firm, which admitted breaching safety regulations, was also ordered to pay costs of £21,000.
Mr Dario was working the night shift on 30 March, 2001, when he started cleaning the machine.
Cambridge Crown Court was told a colleague suddenly heard him scream as he was pulled under the machine.
A post mortem examination showed he suffered multiple fractures to his skull and that he had clearly died "very rapidly".
Pascal Bates, prosecuting, told the court: "Mr Dario suffered horrific injuries.
"He must have been badly trapped between moving parts of the machine.
"The deceased was able to gain access in an area which he should have been prevented from having access to."
Senseless death
Mr Bates said the company, which was founded in 1926 and has 350 employees, kept machinery running all day but did not have the staff to maintain them.
"Had there been a down time, the job of cleaning under the machine, while it was running, would not have been necessary," he said.
James Ageros, for Eternit, said that if managers had been aware of their staff's cleaning practices, the accident would not have happened.
He described the death of Mr Dario, who was regarded as a conscientious worker, as senseless.
Judge Isobell Plumsted fined the company after hearing safety procedures had been changed and there was no risk of the accident happening again.