Joy Mining Australia operates sites at Unanderra and Moss Vale as part of Joy Global, a global mining equipment manufacturing company.

Company spokesman Timothy Fitzsimmons said yesterday operations at Unanderra would be transferred to Moss Vale.

"A review of Joy Global Australasia's regional manufacturing and service capacity has resulted in a decision to cease operations in Unanderra … and transition those to its existing facility in Moss Vale by November 1, 2013," Mr Fitzsimmons said.

"We are continuing to review our operational requirements and are working with our employees and the [Australian Manufacturing Workers Union] to determine the exact number of roles we may be able to relocate to our Moss Vale facility."

But John Stewart, an AMWU official who attended a meeting yesterday with Joy Mining employees, claimed there would be significant job losses.

"There's around 80 employees in Unanderra, and at this point in time, there will be 60 to 70 per cent job losses," he said.

Mr Stewart said Joy Mining's decision to close their Unanderra operations was due to a "worldwide rationalisation" of Joy Mining's operations.

The company owned the Moss Vale site but only leased their Unanderra premises, he said.

"The employees are struggling to understand why this is happening. It's been a good performing unit," Mr Stewart said.

"The Unanderra site is one of the shining lights, and the workers are upset about the closure."