The phrase "a candy factory" is correct and usable in written English.
You can use it when referring to a place where candy is produced or manufactured.
Example: "The children were thrilled to visit a candy factory and see how their favorite sweets were made."
Alternatives: "a confectionery plant" or "a sweets manufacturing facility".
White said the building used to be a candy factory, but I had my doubts.
Her job at a candy factory provided the family with much of its income.
One day I'm designing a candy product; the next day I'm going to a candy factory.
Wrapped in glass and metal, the harborside museum has a cocoa tree garden, a candy factory and a chocolate fountain.
She dropped out of school at 14 to work in a candy factory to help support her family.
— Arsalan Kazemi's father owns a candy factory, churning out gaz, a nougat-and-pistachio concoction that visitors to Esfahan, Iran, buy as a souvenir.
BROOKLYN: 1 Rockwell Place (between DeKalb Avenue and Fulton Street), #3D A two-bedroom two-bath condo in a converted candy factory, with a large, open living area and a parking space in the lot next door.
Mrs. Esposito tried working in a local candy factory for practically peanuts a week, but then she heard about a job in The American Journal of Nursing's subscription department that paid $18 a week.
The company chose to retrofit a former candy factory in Cambridge, Mass., as a laboratory for cutting-edge research rather than build a suburban campus in New Jersey.
They have changed addresses almost every year, from their apartment in a former candy factory across from the bakery, to a 19th-century farmhouse in Connecticut to a mock-Colonial in Rye Brook, N.Y.
Another gripe is the difficulty of coping with local and state laws (witness the need to preserve and move a 1924 candy factory, described by Mr Moores as "a historic building that is historically insignificant in which nothing historically significant ever happened").
