About 300 people joined a "walk for jobs" to protest against redundancy plans at an aircraft engine maintenance plant on Saturday.
General Electric (GE) announced in July that it plans to cut 369 jobs at its site in Nantgarw, near Caerphilly.
A further 180 posts have already been lost since the coronavirus crisis began through voluntary redundancies.
The Welsh Government said it was "doing all that we can to support workers".
Protest organiser Caerphilly Trades Council urged those taking part to social distance and wear masks, as they gathered near Caerphilly Castle for the midday event.
To many 301 members would rather work us out of a job on a Saturday. Every Saturday worked is one less day until the next round of layoffs. Yes covid had a small impact on this crisis but the real reason is mis management from the powers to be. So I wait day by day to get my unprofessional layoff papers Again. Where was the membership leaders from the hall the last 2 rounds of layoffs. In their office or home sleeping in bed. They were not on the floor or in the conference room where they rounded up the cattle and showed us the door.