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moldmakingtechnology.com 35 FOR MORE INFORMATION: PFA Inc. / 262-250-4410 / pfa-inc.com mscanlan@pfa-inc.com CONTRIBUTOR Mark Scanlan is vice president at PFA Inc., designer of the Kor-Lok side-action system for preloading movable cores. properly sized, yields an infinite processing window (at least for movable cores). Figure 3 shows the core slide arrangement in the "set with- out preload" condition and in the "as preloaded" condition, with the indication that the back side of the core/slide is com- pressed toward the core face (dotted lines). As discussed in the previous section, during injection, the injection force (IF) is less than the preload force (PF), so the core face does not move. Available force intensification and locking devices provide additional advantages for producing smaller and stiffer cores and molds. For example, mounting on the outside of the mold base reduces the size of the mold. Combined attributes allow for movement independent of mold opening/closing and for installation after the mold is in the press. The key value in these systems is the ability to preload cores toward the fixed stops and to provide an infinite processing window to moveable cores when and where possible. Moving Forward While any method of preload should provide an infinite pro- cessing window, it is critical to ensure that the amount of preload is sufficiently greater than any likely injection force, that preload is maintained during injection (independent of loss of hydraulics) and that core stops/shutoffs are sized to accommodate the preload force applied. Additional considerations include ease of installation and adjustment for obtaining preload, hydraulic volume (which affects cycle speed), pressure requirements to obtain and main- tain necessary preload, sensor operational limits and what is being sensed for feedback to press inputs, and available servic- es for application reviews that include special considerations such as parting line mounts and opposing cores. The advantages of preloaded cores are available to everyone as long as the basics of preload are understood and care is taken when sizing preload to the application.