Numsa on Tuesday demanded a 20% across-the-board pay rise in the auto assembly, tyre manufacturing, iron, steel, and base metals manufacturing sectors.

"All wage increases, across all sectors, must be based on actual rates of pay and actual wage increases negotiated and not on minimums," National Union of Metalworkers of SA (Numsa) general secretary Irvin Jim told reporters in Johannesburg.

"The duration of the agreements to be negotiated must be limited to one year."

The union wanted an industry minimum of R6 000 a month and an increase of R30 an hour for those earning above R6 000 in the motor industry bargaining council scope.

This minimum wage had to be achieved between now and 2016.

These were the core demands adopted at Numsa's national bargaining conference last week.

On Eskom, Jim said the union wanted an entry level minimum of R12 500 and R5 000 across the board for other levels of workers.

Other demands included a transport allowance, establishing a housing finance corporation to assist workers, and six months full pay maternity leave across all sectors.

The union also wanted skills training and industry-based "worker controlled" medical aid schemes to be established, which would be a move away from "the yoke" of private medical aid schemes.

Jim described this round of negotiations as "extremely strategic".

"We must secure living wages for our Numsa members. This must include closing the apartheid wage gap and achieving skills development," he said.

"At the same time, we must use collective bargaining and our socio-economic demands and campaigns to secure the future of manufacturing, which is the future of our country and the future of metal workers."

Jim said Numsa had a solid mandate from its members on how to approach negotiations, and he urged employers to come to the table with "open cards".

"We want a minimum wage for our members, but negotiations can't just be about money, it must be about the future of the industry."

He said a strike would be a last resort.