An experimental study on the cooling effect of die casting die insert cooling devices

Water is usually introduced into a die insert in die casting through a water line to reduce the temperature of the die insert and thus prevent its cracking. In many cases, a drilled waterline circuit is not possible due to confinement of the space. Bubblers or baffles then become typical water passage systems for die insert cooling. This paper presents an experimental study of the relative effectiveness of bubbler and baffle in die insert cooling. An internally channeled steel cylinder was designed as a die insert, with the blind channel drilled for water-cooling. Commercially available bubblers and baffles were inserted in the channel and water was introduced to cool the specimen when it was either heated in an air furnace or cyclically dipped into a molten aluminum bath. Thermocouples were mounted inside the wall of the cylinder to monitor the variation of the insert temperature under various cooling conditions. Experimental results indicate that both the bubbler and baffle can effectively lower the surface temperature of a die insert, with a bubbler being more suitable to cool a specific "hot spot" than a baffle. For a given cooling channel, within the experimental range, the bubbler with a smaller inner diameter has a better cooling effect to a "hot spot" than a bubbler with a larger inner diameter. Increasing the water flow rate always enhances the heat transfer between the cooling water and the sidewall of the cooling channel.