Tempering or Cooling Systems

 

 

1	The cooling system by drilled holes  is located across the view of the image.
2	In order to get efficient cooling of the core in the cavity, so-called facing cooling baffles are used.

 

Function:

• to quickly get the correct mold temperature at the start-up or after an interruption in the production

• uniform and rapid (economic)  cooling of the melt

• The system should have sufficient capacity to provide a minimal temperature variation of the mold during
  • the work cycle of the machine or
  • the room temperature variations over the day or season of the year.

Mold Temperature is very important process parameter:

• Cooling determines cycle time
•  Affects part quality:

1	Surface finish
2	Strength and structure of the material
3	Dimensions (shrinkage)
4	Tendency to warp
5	Filling ratio
6	The strength of the weld lines

 

Risk:

• Unsufficient Cooling/Temperature affects part quality (see table above)

 

Design:

 

Cavity Cooling:

• All cavity inserts as well as the sliders and splits have to be cooled “directly”, which means touched and wetted by the cooling medium
• cooling water flow in the same direction as the mass which flows into the cavity
• avoid indirect heat transfer
• parallel connections preferred:

• All circuits are fed by a common supply at a similar temperature
• There is a lower temperature differential across the mould.
•  There is a lower pressure drop between inlet and outlet.
•  The mould temperature is more uniform.
•  Circuit blockages are less easily detected.

 

• cooling has to be incuded in Mold-Fill Simulations
• recommended Mold temperature is given by resin supplier

 

Core Cooling:

1	cooling pipe
2	spiral cooling
3	cooling baffle
4	cooling pins made of copper

Temperature Control units:

• external temperature-control units
• central tempering system for the entire production hall

• one unit for each mold half or tempering circuit
• Cooling medium is Water or for higher temperatures than 95 deg Celsius oil

 

Mold temperatures:

 

Cooling medium working range:

 

Conductivity of mold materials: