Guidelines for optimal mold temperature control
- Independent symmetrical cooling circuits around the mold cavities.
- Cores need effective cooling (see baffles, bubblers & thermal pins).
- Short cooling channels to ensure temperature differences between in- and outlet do not exceed 5°C.
- Parallel circuits are preferred over serial cooling as shown in figure below.
- Avoid dead spots and/or air bubbles in cooling circuits.
- Heat exchange between mold and machine should be minimized.
- Differences in flow resistance of cooling channels, caused by diameter changes, should be avoided.
Mold parts that are excessively heated, like sprue bushings and areas near the gates, must be cooled intensively. Rapid and even cooling is enhanced by the use of highly conductive metals, such as beryllium-copper. These metals are used to full advantage in places where it is impossible to place sufficient cooling channels. Beryllium copper transfers twice as much heat as carbon steel and four times as much heat as stainless steel. This does not mean beryllium copper molds will run 4 times faster tan a stainless steel mold but they will run some thin walled parts significantly faster. Beryllium copper is not recommended for materials that require high mold temperatures as they allow so much heat transfer that it is difficult to maintain adequate heat economically.
Cooling of the mold.