Emergency services were called to the factory on Killara Road, Campbellfield, about 9.40am, police spokeswoman Melissa Seach said.

She said that initial investigations suggested a vertical cardboard stacker had collapsed on the man some time between 8.30 and 9.40am.

The man, aged in his 40s, died at the scene.

Police and the Victorian Workcover Authority are investigating and will prepare a report for the coroner.