Unifor members have occupied the Northstar Aerospace plant in Milton, Ont., halting production in a protest over worker pensions as the company prepares to close within two months.

The plant currently produces gears and transmissions for Boeing.

"At the end of the day, this is a company that is closing and our members are going to lose about 25 per cent of our pensions," said Unifor national president Jerry Dias.

Unifor has taken control of Northstar facility at 180 Market Drive, Milton to send <a href="https://twitter.com/hashtag/Northstar?src=hash">#Northstar</a> a msg – fund pension now! <a href="https://twitter.com/hashtag/canlab?src=hash">#canlab</a> <a href="https://twitter.com/CBCHamilton">@CBCHamilton</a> <a href="https://t.co/VFD16oKJUB">pic.twitter.com/VFD16oKJUB</a> —@UniforTheUnion

Dias said Northstar and its parent company, Wynnchurch Capital, have been "inherently disrespectful" leading up to the closure by failing to come to the bargaining table and "see how we can find solutions for our retirees."

A statement released by Unifor accuses Northstar of refusing "to meet the 24 per cent pension shortfall for workers facing job loss."

"This shortfall will affect future and current retirees, some of whom are already on a fixed income after having worked at the facility for more than 40 years," it says.

Unifor Local 112 president Scott McIlmoyle says the pension shortfall is $6 million. (CBC News)

Manny Chhiba says he worked for the company for approximately 28 years and retired about two years ago, and he says he's upset with the cuts.

"They've looked after everybody very well. I'm really surprised that this is happening now," Chibba said. "Everybody knows the tough times now, and the pensioners are really affected."

Unifor Local 112 president Scott McIlmoyle says the shortfall is $6 million and he believes it shouldn't be a problem for the company to fund the pension.

"It's frustrating," McIlmoyle said. "As a president of the local union, I have many corporations that we deal with, and we have had some that have closed for one reason or another and they stepped up to the plate to look after the employees."

Unifor members have occupied the Northstar Aerospace plant in Milton, Ont. (CBC News)

Union to blame for pension cuts, company says

CBC requested a comment from Northstar Aerospace and Wynnchurch Capital.

Heligear Canada Acquisition Co., which purchased select assets of Northstar Aerospace in 2012, told CBC Toronto in a statement it's not to blame for the pension cuts.

"Heligear does not control the pension design or its investments, which are the responsibility of the pension board," the company said. "Any reduction or shortfall is a function of the plan management and design, which are not within Heligear's control."

Heligear Canada Acquisition Co., which purchased select assets of Northstar Aerospace in 2012, says Unifor's actions are 'illegal.' (CBC News)

Instead, it says Unifor is responsible for the state of the pension plan but isn't accepting responsibility for it.

"Unifor does not have a legal basis to hold Heligear responsible and its illegal action to seize control of the Milton facility is a desperate attempt to shift responsibility from Unifor to Heligear, through force, instead."

Unifor enters facility

Beginning at 3:30 a.m. ET on Thursday, Unifor members entered the facility, preventing the start of production. As of 12:30 p.m. ET, they were still inside while a picket line has formed outside.

Unifor members who work for the plant were not at the protest.

Dias told CBC Toronto that management representatives were stationed across the street from the plant, adding he expects to speak with them as well as with Boeing management before the day is done.

Heligear said it's pursuing legal options to regain control of the facility, and said the union's actions poses safety concerns.

"Seizure by Unifor of the facility prevented an orderly and safe shut-down of equipment and processes operating within the facility," the company said. "Until Heligear personnel can re-enter the facility and implement an orderly shut-down procedure, risk of a safety incident exists."