Northern Irish engineering company FG Wilson is to axe up to 760 jobs as it attempts to become more efficient and competitive.
The 760 losses include around 170 agency workers, who were told in June that their jobs would go.
FG Wilson, which makes generators and employs 3,000 people, said its current structure and the tough economic environment meant parts of the business were no longer competitive.
"We need to react accordingly for long-term growth and to compete for industry leadership," Robert Kennedy, the company's Northern Ireland operations director, said.
It announced in June that it was moving production of its 400 series generator sets to Tianjin, China, in order to build the product closer to its growing customer base in Asia.
But Mr Kennedy stressed that Caterpillar is committed to building the remaining business in Northern Ireland, adding that he "genuinely regrets" the redundancies.
The company would offer voluntary redundancy packages and "help redeploy displaced workers by providing training on new skill sets, partnering with potential Northern Ireland employers to host job fairs and hiring a placement service," he said.
Unite union described the job cuts as a "crushing blow" to the region.
"The company has once again thrown industrial relations guidelines back to Victorian times," its regional secretary, Jimmy Kelly, said.
"Our members are spitting tacks at the way they are being treated.
"The company has not given its workers or their union representatives the opportunity to negotiate a plan which would have attempted to keep some of the affected workers employed."
While Northern Ireland enterprise minister Arlene Foster said: "This is devastating for the hundreds of families who will be affected, particularly when so many people are already struggling in this difficult economic climate."
The move came as Northern Ireland's First Minister Peter Robinson led a mini-summit to discuss the worsening economy and Northern Ireland's unemployment rate of 8.2%.