Mineral Insulated Cable Routing Strategies for High Temperature Mould Telemetry
Recessed MI cable routing with thermal expansion loops prevents wire pinch, shields noise, and eliminates press downtime in high-temperature moulds.
Parting Line Bridge
Meaning
A physical feature designed into an injection mould facilitates the continuous flow of resin across the primary parting line into secondary cavities or overflows. Parting line bridge structures allow for the controlled venting of trapped air or the filling of sacrificial tabs used for structural support during secondary operations. This bridge is typically a shallow channel machined into one or both halves of the mould steel.
It must be carefully sized to allow resin passage while remaining easy to remove during the de-gating process.
Flow Management
Strategic placement of these channels helps to balance the filling of multi-cavity moulds. By providing an alternative path for the melt, the bridge can alleviate localized pressure spikes that would otherwise cause part distortion. The geometry of the bridge affects the cooling rate and the strength of the weld line formed at the junction.
Flash Control
Excessive depth in the channel can lead to unwanted flash if the clamping force is insufficient to hold the edges tight. The height of the bridge is often limited to a few thousandths of an inch to ensure the plastic freezes quickly once the cavity is full. Precise machining of the mating surfaces is required to prevent the resin from leaking beyond the intended path.
Ejection Cycle
Parts connected by a bridge must be ejected as a single unit to prevent damage to the delicate plastic features. The ejection system must apply uniform force across the entire assembly, including the bridge and any overflow tabs. Automatic de-gating systems use the bridge as a leverage point to separate the finished part from the runner system.