Cooling circuits are used in a Cool analysis to deliver coolant to areas of the mold that would not otherwise cool effectively.
A cooling circuit consists of a set of connected two-point beam surfaces which make up the cooling system.
The placement of cooling channels is restricted by mechanical constraints such as ejector pins and metal inserts. Information from Cool analyses can be used to evaluate each design. When you are designing a cooling system, consider the coolant inlet, the circuit type, and the circuit location.
Coolant inlet
Prior to running a Cool analysis, you need to identify and set all cooling circuit inlets.
Circuit type
A series circuit that can achieve even coolant flow rate and heat transfer is usually preferable to a parallel circuit.
If it is necessary to use a parallel circuit, each branch should be balanced for local heat load. Poorly designed parallel circuits can have branches where there is little or no flow. The flow in each branch should be controlled so that all of the cooling circuit coolant flowing through them, and that the flow is turbulent for maximum cooling efficency. The following diagram illustrates a series cooling circuit on the left and a parallel circuit on the right.
Circuit location
In general, locate cooling circuits at a distance of about 2.5 times their diameter from the plastic. This will give fairly uniform cooling over the part. In some cases, however, it may be necessary to locate the line closer or further from the part, depending on how much heat is to be removed. Cooling circuits should be close in areas that concentrate heat, such as internal corners and ribs. Cooling circuits can be positioned further away in areas that have less heat content, such as thin sections.
Cooling efficiency
Often molds contain ribs and cores that are very difficult to cool. Placing bubblers, baffles, or metals of high conductivity in these areas greatly improves conduction through the core to the cooling channel.
Do not use small inlet channels to feed larger channels. Remember that the only channels in which turbulent flow is required are the circuits that are actually cooling the part. If a small inlet line feeds a large cooling circuit, achieving turbulence in the large circuit must be accompanied by a large pressure drop over the smaller line. This is a waste of pumping power.
Cooling elements must be assigned a value of heat transfer effectiveness to represent their ability to accept heat from the mold. For most situations a default value is applicable.