Meaning
Active air evacuation from a mold cavity prior to the introduction of melt eliminates resistance and reduces the risk of gas entrapment. Implementing vacuum-assisted injection allows for the production of complex geometries that would otherwise suffer from burn marks or incomplete filling. Vacuum systems use a seal around the parting line to maintain a low pressure environment as the resin enters.
Gas Removal
Trapped air at the end of a flow path causes localized heating that can char the polymer. Using vacuum-assisted injection removes these gases and permits higher injection speeds without damaging the material.
Part Density
Structural integrity improves when microscopic voids are eliminated from the interior of a thick walled component. Parts produced with vacuum-assisted injection show better dimensional stability and higher mechanical strength.
Venting Requirement
Traditional molds rely on small grooves to let air escape under the pressure of the melt. Because vacuum-assisted injection pulls the air out before the melt arrives, the need for deep vents is reduced. Vacuum usage prevents flash and improves the surface finish at the parting line.
Maintenance of the vacuum pump and the mold seals is essential for consistent results. High volume production lines monitor the vacuum level in every cycle to ensure the seals have not degraded.
