This is a part designed to reduce the unwanted heatblock cooling by the hotend-fan of the tronxy x1. It is highly recommended to put some aluminium foil on the inside to further reduce heatloss as well as protecting the print from getting soft.
Tests showed reduction of heatup times from 30 sec to 2 minutes (190° to 230°).
The maximum reachable temperature with this part was 275° where the firmware wouldn't let me increase the head any further (probably to safe the assembly from overheating alltogether).
Whithout the part, the maximum heat topped out at about 230-245°
Print in a orientation so that the layer aren't perpendicular to the overhanging surface.
Printed in PLA, there is the concern of the guard melting because of the heat. I did notice a slight sagging of the free hanging surface after heating the hotend up to 275° without the aluminium foil installed, But it didn't melt at all.
My guess is that with the foil installed, the distance from the heatblock and the constant cooling from the hotend fan is enought to keep the part save over long term.
Will post revisions if changes occure.