Several hundred people have demonstrated against restructuring plans, including 150 job cuts, by the Swissmetal Boillat Group.
The protesters are concerned that the company will close its foundry in the small town of Reconvilier in northwestern Switzerland.
Trade union leaders said up to 1,000 people, including local politicians, took part in the protest in the village of Reconvilier on Tuesday evening.
They called for the factory in the village to remain open and for the company's controversial chief executive, Martin Hellweg, to step down.
The protest came in the wake of an announcement by the Swissmetal Boillat Group that it would axe 150 of its 750 jobs over the next five years.
The company said it was forced to close one of its two foundries in northwestern Switzerland, but refused to give further details.
However, it pledged to maintain factories at both sites and was willing to invest at least SFr25 million ($19 million) at each plant in Reconvilier and Dornach near Basel.
Strikes and protests
The company added that the job cuts were inevitable in order to remain competitive.
The Swissmetal board accused the unions of scaremongering and manipulating employees.
Swissmetal, which manufactures semi-finished copper products, said third-quarter sales had dropped by five per cent to SFr147.4 million, while core profits shrank by half to SFr2.6 million.
The latest protests come just one year after 400 metal workers and staff at the Reconvilier factory staged a major ten-day industrial action against the company's restructuring plans.
Strikes are a rare occurrence in Switzerland.
swissinfo with agencies
A year ago, about 400 staff and workers at Swissmetal in Reconvilier staged a major strike against company restructuring plans.
The ten-day action ended after an agreement between the unions and the company board which guaranteed future investment in the Reconvilier plant.
Swissmetal third-quarter figures:
Sales: SFr147.4 million (-5%)
Core profit: SFr2.6 million (-50%)
The company suffers from overcapacity in the sector and the high price of copper on the commodity market.