The unit, where plastic wastes are processed for manufacturing of recycled items at Ukkadam, was locked last night by the owner, they said.
The blaze was noticed in the wee hours and the fire and rescue personnel took four hours to douse the flames, police said.
Packing and processing machines, plastic items and a motorcycle were gutted in the fire and the loss was estimated to be around Rs 30 lakh, they said.
Though short circuit was suspected to be the cause of the fire, police are investigating it, they added.