TABLE OF CONTENTS Silicone rubber sleeve cores are a more recent development and can be quite useful for noncritical applications.
This system again uses a split core similar to the conventional collapsible core or a tapered pin construction depending on the severity of the undercut form. In this case the core pin carries a silicone rubber cap or sleeve at its tip, which has the thread form incorporated into it. When the mould tool is in the closed position, the rubber sleeve is kept stressed by the core pin. With a collapsible core design the tool opens and the core pin retracts and collapses, allowing the silicone sleeve to distort and permit the moulded thread form to be stripped off over it.
This is a cheap alternative system for use with simple, straightforward thread forms where thread form accuracy is not particularly important.
It is a simple alternative method for noncritical thread forms.
It avoids split line witnesses associated with segment-type cores.
Maintenance costs are lower as flash is less likely to form.
It is considerably cheaper than split segment cores.
Not recommended for accurate thread forms or large production runs.
Silicone sleeves need regular replacement.
Heat conduction from silicone is not very good.
Cooling cycles are longer.
Although the silicone sleeve has to be replaced regularly, the sleeves are very cheap. However, the mould tool would have to be stopped to permit replacement on a regular basis. Silicon sleeve inserts would not...
