iPact Melt Pressure Control

How does it work?

Internal Melt Pressure

The Internal Melt Pressure is the minimum static pressure existing within the melt to counterbalance the shrinkage forces and air resistance in the cavity during fill and final solidification. The static pressure also gives the melt higher mobility to "feed" the volumetric deficit in fast solidification areas, thus eliminating sink and controlling shrink and density.

Internal Melt Pressure is the summation of dynamic pressure changes resulting from the melt flowing into various mold sections.

A single process variable is generated and sent to the hydraulic unit, resulting in injection pressure adjustments that automatically and continuously control the Internal Melt Pressure.

With this Internal Melt Pressure control, each section of the part being filled solidifies with equal pressure, balanced flow, and reduced stress.

iPact with Intellimold Control

The iPact with Intellimold system provides communication between melt and cavity by placing transducers in the machine's nozzle and the cavity's "last-place-to fill" location.

The iPact with Intellimold controller is used to establish and maintain, during injection, a targeted constant Internal Melt Pressure which is generated by scanning and compensating for flow restrictions within the mold (Mold Resistance), Partial Solidification of the part during fill, various melt property differences (Viscosity), and Air Resistance at the melt front, etc.

The iPact control is Open Architecture so that other variables may be added to the single process variable calculations, as needed. The Internal Melt Pressure is the most positive parameter available for the closed-loop control during injection molding of thermoplastics. It does not require a velocity to pressure transition. The cavity pressure profile control loop will compensate for most conditions or environment variations. Without changing any control parameters it will compensate for variations of mold temperature, resin temperature, and viscosity. This control method will perform consistently even with varying hydraulic oil temperature or screw and check ring performance, because iPact with Intellimold compensates for these variations. This method eliminates the need to implement the velocity to pressure transition and allows the operator to control the actual condition of the melt inside the cavity.

Most injection-molded parts can be produced by a one stage Internal Melt Pressure set point. The iPact Intellimold process allows inputting of the ideal molding specifications for the resin. Resin manufacturers develop resin-molding specifications and set guidelines for the proper processing of the resins they manufacture. One of these guidelines is the ideal melt pressure that should be used for processing the material. Unfortunately there is no way to enter this ideal melt pressure into the screens provided by injection molding equipment manufacturers. If molding conventionally, the operator is forced to guess which modifications need to be made to best closely resemble the ideal melt pressure. Or they will ignore the ideal melt pressure recommendation and mold the material however they see fit. In essence, many traditional molding operations violate these guidelines, including processing the resins at higher than recommended temperatures and pressures. The result is plastic that is not ideally processed, which results in parts with molded-in stress. 

The iPact with Intellimold process uses these recommended molding guidelines as a processing target. There is actually a place to enter the recommended melt pressure provided by the resin manufacturers. By continuously sensing the internal melt pressure and making adjustments, iPact ensures the material is properly processed, and therefore the part is properly processed.

iPact processes the material in the same manner that the physical and mechanical properties are warranted by the resin manufacturers. iPact with Intellimold acts like an auto pilot for injection molding machines. The iPact process provides the possibility of creating a closed loop system, between the melt holder (injection nozzle) and mold cavity, under which any subsequent pressure variations are measurable in real time and controlled accordingly.

The pressure transducers in the mold cavity and in the machine nozzle continuously provide signals to the pressure controllers and a core process variable is derived. The signals are fed through the iPact with Intellimold software and a series of calculations are made whereby a single process variable is mathematically derived. This variable represents the static pressure of the melt (Internal Melt Pressure) in the cavity based upon flow rate, melt temperature, modulus, shrinkage factors, part configuration, and the level of stress as the part is constrained in the cavity during solidification.

iPact with Intellimold can control some of the uncontrollable variables that exist in the injection molding process. Any of these conditions can have a negative affect on the quality of the part during the conventional molding process. With the iPact with Intellimold process, these conditions do not affect part quality. However, they do have an impact on the Internal Melt Pressure.

The iPact process compensates for any changes in the Internal Melt Pressure to ensure that it is constant and unchanging, thereby consistently producing a quality part.