DME Mold Components

How and where heat pipes work The DME Heat Pipe is a heat transfer device specifically designed for optimal performance in plastic injection molds. It consists of a vacuum-tight copper tube containing a wick and a non-toxic working fluid. One end of the heat pipe is an evaporator, the opposite end is a condenser. Thermal energy is gathered at the evaporator end, vaporizing the working fluid. This vapor then travels through the Heat Pipe to the condenser end. At the condenser end the vapor condensates back into a liquid, giving up its latent heat in the process. To complete the cycle the condensed liquid then travels along the wick, via capillary action, back to the evaporator section. This process repeats itself continuously, transferring heat many times faster than pure copper. How heat pipes are used Available in a variety of standard lengths and diameters, DME Heat Pipes are used in cores, core slides, cavities and other areas of a mold or die requiring cooling or controlled temperatures. Commonly used in place of bubblers, baffles, fountains or blades, Heat Pipes transfer heat rapidly to the coolant, rather than requiring the coolant to flow into the heated area. They are also used to transfer heat to a cooler portion of the mold (which serves as a heat sink) or to open air, thereby permitting cooling of otherwise inaccessible areas and eliminating potential coolant leakage. Standard injection molding heat pipes The standard line of Heat Pipes for injection molding includes both a low-temperature (TPL) and a high- temperature (TPH) series. The TPL Series works most efficiently between the temperatures of 40° and 200°F with a coolant temperature of approximately 60° to 80°F, and the TPH Series between 150° and 400°F with a coolant temperature of approximately 90° to 110°F. The sealed end of each heat conductor is color-coded (BLACK for the TPL series and WHITE for the TPH Series). Selection of the appropriate series is based on the application’s melt, mold surface and coolant temperatures to which the Heat Pipe will be subjected. Bene ts of heat pipes Cool Molds Faster and Reduce Cycle Time The Heat Pipe’s ability to cool molds faster and thus reduce cycle time is due to a number of factors. First, waterlines throughout the entire mold can be larger in diameter, permitting a higher coolant velocity, which transfers heat faster. Second, the larger volume of fluid flowing through the waterline results in a lower overall coolant temperature rise, so that the last Heat Pipe in the system will transfer heat as efficiently as the first. Third, the extension of the Heat Pipe into the waterline promotes turbulent flow, which transfers heat faster than laminar flow. Fourth, the ability to transfer heat away from inaccessible areas improves the overall cooling rate and reduces cycle time, even if extension into a remote waterline is impractical or impossible. Improve Part Quality As the Heat Pipe transfers heat to the coolant, air or mold component, it also dissipates heat evenly along its entire length. This isothermal action provides faster and more uniform cooling, thus eliminating hot spots, which cause sink marks, pulling and spotting. Simplify Mold Design and Lower Costs With Heat Pipes, waterline design is greatly simplified since coolant flow into the heated area of the mold is not required. In addition, the ability to locate heat conductors in areas inaccessible to other cooling devices can further simplify the overall mold design. In most cases, the machining and construction time required for the mold is reduced, lowering moldmaking costs. HEAT TRANSFER INTERNAL OPERATING TEMPERATURE OF HEAT PIPE MAXIMIZING EFFICIENCY WITH WARM COOLANT Heat Pipes work best when the coolant is between 60° and 110°F, and sometimes higher. The graph illustrates how the Heat Pipe’s heat transfer capability is dependent upon its internal operating temperature. It is best to start with the coolant temperature high, then reduce it if necessary. EVAPORATOR END HEAT IN CONDENSER END HEAT OUT WICK LIQUID VAPOR MOLD COOLING Heat Pipes - Cooling Pins U.S. 800-626-6653 ¦ Canada 800-387-6600 ¦ dme@milacron.com ¦ www.dme.net ¦ store.milacron.com 246 Mold Cooling Heat Pipes - Cooling Pins

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