A walkout by Pilkington workers in July alarmed car manufacturers, which use the company's glass for windscreens.
The July strike ended - without any disruption to car manufacturers - with the workers winning a 9% pay rise over 27 months. Despite an agreement being in place, unions remain concerned over labour hire and income protection at the sites.
An application to stop the industrial action proposed for next week was lodged in the AIRC Friday, but after more than three hours of talks failed to reach a resolution.
Commissioner Anna Lee Cribb ordered the parties to return to the commission for a compulsory conference at 9.30am this Thursday.