A Preliminary Study of Sealing and Heat Transfer Performance of Conformal Channels and Cooling Fins in Laminated Tooling

Abstract

Rapid tooling (RT) methods allow for almost complete flexibility in routing of conformal cooling or heating channels within a mold for enhanced thermal control, but tool size is currently limited. A notable exception is the profiled edge laminae (PEL) method, which is a thick-layer laminated RT method intended for large-scale tooling applications. One of the biggest design issues with incorporating conformal channels in a PEL tool is to effectively seal the channels rapidly and inexpensively. Prior attempts in the literature at sealing laminated tools using diffusion bonding or brazing have been just the opposite. Recognizing that many manufacturing applications requiring large-scale tools (e.g., thermoforming, composites forming) do not need the temperature resistance and strength of either diffusion bonded or brazed laminae, this paper investigates alternative sealing methods. It is shown through a preliminary experimental study that (i) manual application of high-temperature adhesives locally around conformal channel holes will effectively seal channels for working fluid temperatures and pressures typically encountered in thermoforming over an extended period of time, and (ii) heating and cooling performance is similar to that of a continuous tool. Localized sealing is actually an advantage when tool porosity is needed. In addition, a novel approach to incorporating cooling fins into the nonforming side of a PEL tool is demonstrated, but thermal performance is poor as compared to conformal channel cooling. Finally, it is shown that simple one-dimensional analytical models can be used to effectively predict tool performance if a conformal channel cell design methodology is used.