Workers at the Alcan plant in Lynemouth near Ashington in the north east of England, begin industrial action on Monday as part of a long running pay dispute.
More than 410 GMB union members are on an overtime ban. The company which employs 600 workers is a major supplier of aluminium to the manufacturing industry.
The overtime ban is expected to cause huge knock-on problems for a number of manufacturers which require aluminium as a raw material, such as those in the aircraft and car industries.
The GMB members at the factory want to see the current bonus scheme scrapped in favour of a higher basic wage.