Decoupled III

Sensor Trigger

Feedback from within the mold provides the primary signal for the machine to switch from high speed filling to pressure control. In a decoupled iii setup, the cavity pressure reaches a pre-defined threshold that immediately signals the press to transition. This is faster and more accurate than waiting for the screw to hit a physical limit on the barrel.

It ensures that the exact same amount of work is performed on the plastic in every single shot. The controller must be capable of processing these high speed signals without delay to prevent over pressurization. High speed data acquisition is necessary because the transition happens in a fraction of a second.

If the signal is late, the mold could be damaged by a pressure spike. This sensor should be placed at the end of the flow path or near a critical feature to ensure the part is fully formed before packing begins.

Melt Behavior

Variations in the flow characteristics of the resin are compensated for by the internal measurement. When using decoupled iii, a stiffer lot of material will naturally require more hydraulic pressure to reach the cavity sensor. The machine automatically provides this force because the trigger is based on the arrival of the plastic at a specific point in the tool rather than screw travel.

This isolates the part quality from the fluctuations common in regrind or different batches of virgin resin. It creates a more stable viscosity environment within the cavity itself. This stability is required for thin wall parts where the window for error is extremely small.

The process adjusts for environmental changes in the factory such as oil temperature or ambient humidity that might otherwise drift the process.

Cycle Precision

Accuracy of the final part dimensions is the main result of this control strategy. By implementing decoupled iii, the molder reduces the standard deviation of part weight and critical dimensions across a long production run. The packing phase starts at the exact same moment relative to the flow front reaching the end of the cavity.

This prevents the flash or short shots that occur when a process is tuned only to machine position. It allows for a much tighter tolerance on functional components. Processors who use this method often see a reduction in scrap rates and a more predictable maintenance schedule.

Monitoring the peak pressure and the pressure at transfer provides a complete picture of the health of the mold. The digital records created by this method are essential for medical or automotive parts where traceability is a requirement. This level of oversight ensures that any shot that deviates from the established norm is automatically diverted to a scrap bin.

It provides a level of certainty that machine centered processes cannot match.