Craig Matthews, 62, was annoyed that he had been suspended from his post as a forklift driver for “writing poetry at work”, York Crown Court heard. He later resigned.
Judge Simon Hickey told him he had made himself a “real nuisance” by persistently trying to get back onto the site of Greencore food factory in Barlby near Selby.
Nick Peacock, prosecuting, described how Matthews smashed the door window of the security gatehouse with a golf club on December 2.
“Come out, I will smash your face in, come out and fight,” he told security staff. Then he tried to climb through the broken window, but staff inside fended him off with a metal coat stand until police arrived.
Officers had to pepper spray him two or three times before they could handcuff and arrest him, said Mr Peacock.
Matthews, of Oak Drive, Newport, between Goole and Brough, pleaded guilty to affray, having an offensive weapon and criminal damage.
He was jailed for five months and ordered to pay £250 compensation to the company and £85 prosecution costs.
He was also banned from going within 100 metres of the factory or mentioning the company on social media for five years under a restraining order.
His barrister Rhianydd Clement said he was no longer “obsessed” with his ex-employer and didn’t want to go to the factory site.
Matthews had no previous convictions. He had said he was “hearing voices” at the time of the incident and a psychiatrist had said he appeared to have depression and anxiety but had not made a formal diagnosis.
“It seems a reasonable conclusion he was suffering from something psychiatric that was related to the offending,” she said.
Mr Peacock said Matthews resigned from his job on October 31.
He told police he had been suspended in September for “writing poetry at work while employed as a forklift driver” and the company had not given him sufficient mental health care.
Starting on November 10, Matthews kept making “unwanted and uninvited” visits to the site. Initially he asked for some cardboard boxes, was asked to leave and was escorted off the premises.
On November 14, he made two such visits.
He was told he was barred from the site, but continued to keep coming and the company ordered its gate to be locked to prevent further visits.
On November 30 he first threatened to “smash in the faces” of a security staff officer who was dealing with him and he repeated the threat in a visit the following day.
On December 2 he drove up to the security gate house and attacked the door.
