Staff at four New South Wales juvenile justice centres have walked off the job to fight for their safety after two violent attacks on officers in the past two days.

On Friday, an officer was assaulted at the Frank Baxter Centre near Gosford and on Saturday an officer suffered a concussion, a broken nose and broken eye socket after being punched eight times by an offender at the Cobham Centre in Sydney's west.

Images taken after the attack show the officer with a bloodied shirt and major facial trauma.

Workers are fed up with coming to work and putting themselves in harm's way, the Public Service Association (PSA) said.

"Not a day goes by when there isn't some kind of violent incident across the state in these juvenile justice centres," acting general secretary Troy Wright said.

Staff at Cobham, Frank Baxter, Riverina, Acmena all stopped work for six hours under the Work Health and Safety Act.

Mr Wright said the officers were frustrated with what they say is a failure on the part of the NSW Government to address staff safety.

"What does it take for this government to get serious about the state of juvenile justice in NSW?" he said.

Shortly after the walk-off, the PSA met with the Industrial Relations Commission and a number of changes were agreed upon.

"We will facilitate the movement of some 18-year-olds who are causing problems into the adult system," a spokesperson for Juvenile Justice said.

The officer was punched eight times by an offender at the Cobham centre. ( Supplied: Public Service Association )

Next week the department and union will meet again to discuss amendments to the Detention Centre Act.

The officers agreed to return to work shortly after the meeting.

The PSA said there must be action on their demand for therapeutic units across juvenile detention centres as they could help officers manage high-risk offenders and improve rehabilitation opportunities.

Mr Wright said they wrote to the department but received no reply.

"Instead the department moves high-risk offenders around the state. Every juvenile justice officer knows that it could be them on the end of a punch, spat on or attacked," he said.

The department's spokesperson denied ignoring the request and said discussions about the therapeutic units were ongoing.

