After 18 years working at the Streets ice-cream factory in the Sydney suburb of Minto, Michelle Parkin is "hugely nervous" about her future on a single income.

The 57-year-old grandmother is among 140 workers facing an uncertain future since the company applied to the Fair Work Commission to terminate their existing enterprise agreement on wages and conditions.

The Australian Manufacturing Workers Union, which represents the factory workers, has warned them they face a pay cut of up to 46 per cent of their wage if their current agreement is terminated and they fall back onto the award.

Ms Parkin, who has three adult children, the youngest aged 21, takes pride in her work as a machine operator.