Parting Line Shut-off

Precision Engineering

Tooling surfaces must be ground to extremely tight tolerances to ensure they mate perfectly. If the parting line shut-off is damaged by trapped debris or high clamping forces, the seal will fail. Regular maintenance and cleaning of the mold faces are required to preserve the integrity of this contact area.

Venting Efficiency

Air must escape from the cavity as the plastic enters, but the resin must be stopped at the boundary. Small grooves are often ground into the parting line shut-off to allow gas to vent without letting the melt through. The depth of these vents is usually less than 0.03mm for most resins to ensure no flash is produced.

Tool Longevity

Wear on the shut-off surfaces occurs over hundreds of thousands of cycles. As the metal erodes, the parting line shut-off becomes less effective, and the risk of part defects increases. Steel selection and hardening treatments are chosen to extend the life of these critical sealing zones.