Mr Hawea was attempting to fix a fault in the machine by applying tension to a wire cable.
The machine was in operation at the time and the cable had tightened itself as he touched it.
The wire had caught his hand and as he tried to pull it out the tip of his left little finger was sliced off.
WorkSafe New Zealand, represented in court by lawyer Jamie Eng, found that the machine was not adequately guarded to prevent workers accessing dangerous moving parts in the tripper room.
WorkSafe New Zealand chief inspector Keith Stewart said the loss of Mr Hawea's finger was "completely avoidable".
A major New Zealand company its health and safety systems should have identified the hazard and should have had proper guarding in place to minimise the risk, Mr Stewart said.
"Proper guarding of the dangerous moving parts of machines is basic stuff," he said.
"Ravensdown should have ensured that guarding in the tripper room was up to scratch and in line with the Safety of Machinery Standards."
No Ravensdown representative was available for comment last night.