The Haydens Bakery worker's ring finger required partial amputation after the 3 March 2015 accident.
The Health and Safety Executive found that the company had modified the machine by adding a securing clip to a rotating shaft but failed to identify and address the additional risk created.
Haydens Bakery pleaded guilty to breaching Regulation 11(1) of the Provision and Use of Work Equipment Regulations and Regulation 3(3) of the Management of Health and Safety at Work Regulations, which cover dangerous parts of machinery and risk assessment. It was fined at Swindon Magistrates' Court.