Two managers and one worker at the Future Green Unit at Holystone Industrial Estate, Hebburn, were targeted for violent retribution by the angry trio.
Newcastle Crown Court heard Sam Laidlow had been dismissed from the firm a few weeks earlier and had told his family he was "bullied and treated badly" during his employment.
Shortly before 9am on June 20 last year the 25-year-old returned to his former workplace with his older brother Ben Laidlow, 29, and dad Lawrence Laidlow, 55.
The court heard the men hunted down one employee, who was wearing ear plugs as he worked, and brutally attacked him from behind.
The furious dad then sought two members of the management team and lashed out at them but did not cause serious injury.
The worker who was attacked by all three men, who armed themselves with hammers and metal bars from the factory during the violence, suffered a deep laceration to his ear that needed seven stitches, a cut lip and was badly bruised.
During the violence the attackers told the victim, who was on the floor bleeding: "You are not so hard now."
Judge Sarah Mallett said: " He was hit from behind then all three of you set about him, punching him and kicking.
"The attack continued after he was on the floor."
The court heard when the men were arrested, Sam Laidlow produced a written statement outlining the bullying he had been subjected to.
Defence barristers said his ordeal was "bullying, more than factory banter".
Sam Laidlow, of Staindrop, Leam Lane, Gateshead, admitted causing grievous bodily harm and was sentenced to 18 months' imprisonment, suspended for two years.
Judge Mallett said he was a vulnerable, hard working young man who acted out of character and added that he has "low self worth due to bullying in work places and earlier at school."
Ben Laidlow, of Great North Road, Gosforth, Newcastle, also admitted causing grievous bodily harm and was sentenced to 21 months'imprisonment, suspended for two years.
The judge said she accepted his explanation that "things went too far" and said he is an "articulate and intelligent" man who has just become a father.
Judge Mallett told him: "Your family loyalty came to the fore when you realised what had been happening at work, which was properly categorised as workplace bullying."
Lawrence Laidlow, of Mowberry, Desborough, Northants, who is about to set up his own business and has served time in the military, admitted causing grievous bodily harm and two offences of common assault.
He was sentenced to two years' imprisonment, suspended for two years.
Judge Mallett told him: "It was a terrible example you set to your sons.
"It may well be you were, understandably, upset as a result of the bullying of Sam but you took a course that could never be justified in any circumstances.
"The consequences of that were three people were assaulted.
"What you did was wrong and you know that."