They are striking over salary increase dispute.
The metal-workers are asking for an 8% salary increase and reject a 4% living wage.
Workers are expected to march to the Metal and Engineering Industries Bargaining Council.
Numsa says employers are using the COVID-19 pandemic as an excuse to not meet their demands.
KwaZulu-Natal Numsa secretary Mbuso Ngubane says they are rejecting the current offer.
“We are rejecting it on the basis that we think that it is not reasonable. Especially when you look at the state of affairs in terms of the goods that are so expensive or the necessities that are so expensive where our members are expected to be able to put bread on the table for their families.”
Phakamile Hlubi-Majola, NUMSA spokesperson says they will fight until their demands are met.