Non-time dependent calculated variables based on measured strain are used to effectively determine an optimal hold profile for an expanding crosslinking polymer part in a mold cavity. A system and/or approach may first inject molten expanding crosslinking polymer into a mold cavity, then measure strain at the mold cavity or at another location within the injection molding system, and then calculate at least one non-time dependent variable during an injection molding cycle. Next, the system and/or method commences a hold profile for the part, and upon completing the hold profile, the part is ejected from the mold cavity, whereupon a cure profile is commenced.

An injection molding machine includes: a clamping device having a fixed mold and a movable mold, configuring a mold, and a clamping force sensor to detect a clamping force of the movable mold to the fixed mold; an injection device having an injection nozzle and a screw to fill the mold with a molten resin via the injection nozzle; and a control device, wherein the control device monitors a variation of the clamping force from the clamping force sensor, causes a slow speed forward movement time at a timing of VP switching to be increased if the variation exceeds a predetermined upper limit, and causes the slow speed forward movement time at the timing of VP switching to be reduced if the variation falls below a predetermined lower limit.