Mold temperature controller is a small equipment which used for heating the connected mold to obtain the correct operating temperature in a minimal or specified time and maintain the set temperature by heating or cooling. There two types of mold temperature controller on the market, oil type and water type.
Heat transfer medium of mold temperature controller are water or oil. Both water type and oil type have positive points and negative points.
# Water type:
– Positive :
More economical, cleaner and less problems. In the case of leaks in the temperature control circuit, water loss may simply run into the drainage system without any further precautions.
– Negative :
- Low boiling point for water
- Water quality, in the risk of corrosion and calcification of temperature control system and mould which will eventually decrease the flow in the mould and to deterioration of heat exchange between the mold and circulating water.
# Oil type:
– Positive :
Thermal oil doesn’t present the negative of water. Boiling point for oil is higher and can be used for temperature up to above 350 No corrosion and calcification of temperature control circuit.
– Negative :
- Heat transfer efficiency is approximately one third of water.
- Production odours starting at 150℃
- in open systems/
- Tend to cracking( property degradation)
- Flammable under certaion conditions
- Not particularly suitable for moulds with very small heating/ cooling channels
The selection of the temperature control bases on
- Resin( determines mold temperature and types of heat transfer medium)
- Weight of mould(kg), required warming up time -for calculating heating capacity
- Material throughpur(kg/h) – for calculating cooling capacity
How to calculate required heating capacity in kw
A x ( B – C )= kcal / h
Kcal / h divide by 860=kw
A = net weight of mould( kg ) x specific heat capacity of mould material (refer to table A )
B = operating temperature of mould( ℃ ) (refer to table B)
C = initial temperature of the mould( ℃ )
How to calculate required cooling capacity in kcal / h
D x E x ( F – G ) = kcal / hr
D = throughput of raw material ( kg / h )
E = specific heat of raw material – specific heat of raw material( ℃ ) – ( refer to table B )
F= melt temperature of raw material( ℃ ) – refer to table B
G= operating temperature of the mould( ℃ ) – refer to table B
TABLE A Specific heat value
|Material||Specific Heat ( kcal / kg ℃ )|
|Oil||0.45 ( at 100 ℃ )|
|ASA， PMMA, POM copolymer||0.36|
|PP reinforced, PC, PVC rigid||0.36|
|ABS, PC, PVC rigid||0.29|
|PET||0.3 ~ 0.55|
TABLE B Typical processing temperatures for resin.
|Material||Melt temperature ℃||Mould temperature ℃|
|ABS||240 ~ 280||50 ~ 80|
|SAN||200 ~ 270||40 ~ 80|
|ASA||240 ~ 280||40 ~ 80|
|ASA+PC||260 ~ 300||60 ~ 90|
|PMMA||200 ~ 260||50 ~ 80|
|LDPE||170 ~ 240||10 ~ 40|
|PP||200 ~ 270||10 ~ 40|
|HDPE||180 ~ 270||10 ~ 40|
|PS||180 ~ 260||10 ~ 40|
|PA 66||280 ~ 300||40 ~ 60|
|PA66+ GF||285 ~ 310||80 ~ 120|
|PA 6||230 ~ 290||40 ~ 60|
|PA 6+ GF||260 ~ 290||80 ~ 120|
|POM copolymer||180 ~ 230||60 ~ 120|
|PBTP||245 ~ 270||60 ~ 80|
|PES||320 ~ 360||140 ~ 160|
|PSU||310 ~ 360||120 ~ 160|
|PC||280 ~ 310||80 ~ 120|
|PVC||170 ~ 210||20 ~ 50|
The selection of hose
The suggestions base on the safety in operation and should be confirmed by supplier.
1.water up to 90℃ High temperature, fabric reinforced rubber hose
oil up to 120℃
- water up to 200℃ PTFE, stainless steel braided hose
Oil up to 250℃
- oil up to 350℃ All stainless steel flexible hose
Generally the hoses distinguished as two parts. One part connect with cooling water of injection molding machine, another one connected with mold. For mold, there’re input hoses and output hoses. The supplier will marks the way of connection.
Many manufacturers don’t think mold temperature is important and don’t order it yet. But there are many benefits, such as
- Pre-warming the mould to reach the correct temperature.
- Productivity in terms of cycle time.
- Reduce reject rate at the period of machine starts up.
- Process consistency to sustain product quality, ultimately affect the plastic parts price.