The news comes after the Competition Commission gave the green light to Long Clawson's acquisition of the business last month.
The commission had suggested it did not see Hartington as a viable business.
"We must progress our consolidation plans, taking unnecessary cost out of our business to remain competitive," said chief executive Martin Taylor.
Long Clawson was working with employees, their representatives and local employment agencies in an attempt to find alternative employment for staff, he said.
Manufacturing currently undertaken at the Hartington site would be handled by the company's other operations. The future of the site itself, which dates from the 1870s, is still to be decided.