Specific Process Knowledge/Back-end processing/Polymer Injection Molder/MoldTemp: Difference between revisions

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In this type of process the mould remains at the same temperature during the entire injection moulding cycle. The temperature should not exceed the glass transition temperature of the polymer being used. Otherwise the polymer will never get cold enough to solidify to a degree where it can be demoulded without being deformed/damaged. How close one can get to the glass transition temperature depends on several factors like e.g. polymer type, cooling time and whether the polymer has a tendency to stick to the shim (especially an issue when replicating high aspect ratio structures). With Topas 5013L-10 (which has a Tg around 135°C) one can often go up to 100°C and for samples that are easy to demold even higher (110-120°C). For polymers with very low Tg (such as e.g. flexible polyurethanes) one often has to run as cold as possible. With the mould heeting switched completely off and mould cooling water fully open, the lowest achievable mould temperature is around 15°C.
In this type of process the mould remains at the same temperature during the entire injection moulding cycle. The temperature should not exceed the glass transition temperature of the polymer being used. Otherwise the polymer will never get cold enough to solidify to a degree where it can be demoulded without being deformed/damaged. How close one can get to the glass transition temperature depends on several factors like e.g. polymer type, cooling time and whether the polymer has a tendency to stick to the shim (especially an issue when replicating high aspect ratio structures). With Topas 5013L-10 (which has a Tg around 135°C) one can often go up to 100°C and for samples that are easy to demold even higher (110-120°C). For polymers with very low Tg (such as e.g. flexible polyurethanes) one often has to run as cold as possible. With the mould heeting switched completely off and mould cooling water fully open, the lowest achievable mould temperature is around 15°C.


{| border="1" cellspacing="1" cellpadding="2"  align="left"
! Parameter
! Benefits
! Drawbacks
|-
|Low mould temperature||Col2_row1||Col3_row1
|-
|High mould temperature||Col2_row2||Col3_row2
|-
|}




{| border="1" cellspacing="1" cellpadding="2"  align="left"
! Col1_head
! Col2_head
! Col2_head
|-
|Col1_row1||Col2_row1||Col3_row1
|-
|Col1_row2||Col2_row2||Col3_row2
|-
|}


=== 2. Variable mould temperature (Variotherm) processes ===
=== 2. Variable mould temperature (Variotherm) processes ===

Revision as of 13:16, 24 August 2016

Mold temperature setup

Injection moulding processes can be divided into two different types:

  1. Constant mould temperature processes
  2. Variable mould temperature (Variotherm) processes


1. Constant mould temperature processes

In this type of process the mould remains at the same temperature during the entire injection moulding cycle. The temperature should not exceed the glass transition temperature of the polymer being used. Otherwise the polymer will never get cold enough to solidify to a degree where it can be demoulded without being deformed/damaged. How close one can get to the glass transition temperature depends on several factors like e.g. polymer type, cooling time and whether the polymer has a tendency to stick to the shim (especially an issue when replicating high aspect ratio structures). With Topas 5013L-10 (which has a Tg around 135°C) one can often go up to 100°C and for samples that are easy to demold even higher (110-120°C). For polymers with very low Tg (such as e.g. flexible polyurethanes) one often has to run as cold as possible. With the mould heeting switched completely off and mould cooling water fully open, the lowest achievable mould temperature is around 15°C.

Parameter Benefits Drawbacks
Low mould temperature Col2_row1 Col3_row1
High mould temperature Col2_row2 Col3_row2



Col1_head Col2_head Col2_head
Col1_row1 Col2_row1 Col3_row1
Col1_row2 Col2_row2 Col3_row2

2. Variable mould temperature (Variotherm) processes

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