Stopper Plates for Die Cast

Die cast stopper plates pair with ejector retainer plates and ejector backing plates to create a positive stop mechanism for the ejection system. They set the maximum ejector stroke length and prevent over-travel that could damage the casting or the mold. In a die casting mold, stopper plates are typically installed at the four corners of the ejector assembly, contacting the support plate face when the ejector reaches full forward position.

1045 is a medium-carbon steel (0.45% C) offering an optimal balance of impact toughness, surface hardness (28–32 HRC after heat treatment), and machinability. Stopper plates absorb repeated impact loading during every ejection cycle — they must resist deformation without cracking. Higher-carbon steels would be harder but more brittle under impact. Lower-carbon steels would deform permanently. 1045 in the normalized or quenched-and-tempered condition provides the best combination for this cyclic impact application.

Standard stopper plate thickness options: 6 mm, 8 mm, 10 mm, 12 mm, and 16 mm. Thickness selection depends on the ejector stroke length and impact force. For die casting molds up to 500 tonnes, 8–10 mm is typical. For molds 500–1,000 tonnes, use 12–16 mm. The stopper plate face should be ground flat to within 0.02 mm to ensure even load distribution across all stopper positions and prevent rocking during impact.