Northallerton Magistrates Court heard that in February 2015, Thomas of York had removed parts of a pastry lid maker's guarding system to improve its operation. The guards were not replaced when the modification proved to be ineffective.
The man broke several of his fingers when his hand was pulled into the machine.
Thomas of York, from Helmsey, York, pleaded guilty to breaching Regulations 11 and 14, of the Provision and Use of Work Equipment Regulations and was fined £6,500 and ordered to pay £691.45 in costs.
After the hearing, HSE Inspector Julian Franklin said: "Modifying machines should always involve a reassessment of the safety of that machine. Guard checking routines should be periodically audited to ensure they remain effective.