Meaning
Molecular forces at the interface of a tool and a polymer melt dictate the wetting behavior and release characteristics of the part. Low mold surface energy prevents the resin from bonding to the steel or ceramic surface during the cooling phase. Moulders use coatings like polytetrafluoroethylene or chrome to adjust these forces and reduce the need for external release sprays.
Release Behavior
Part ejection becomes more reliable when the attraction between the polymer and the tool is minimized. If the mold surface energy is too high, the plastic clings to the cavity walls and causes deformation or pin push marks.
Coating Application
Surface treatments alter the chemical profile of the tool to lower its polar and dispersive components. Measuring mold surface energy with contact angle goniometry confirms that the treatment was applied uniformly across the geometry.
Cycle Time
Thermal efficiency and ejection speed determine the overall productivity of the molding cell. Reducing mold surface energy allows for faster ejection at higher temperatures without tearing the skin of the part. Shorter cooling times are possible because the part does not need to be as rigid to survive the mechanical force of the ejector pins.
Dwell time reduction lowers the piece price of the component.
