Description: In upgraded version of Creatbot DM plus, an all metal hotend is used. All metal hotend can reach a temperature of upto 300 degrees centigrade and thus various new filament materials like PC can be printed. Generally a PTFE & PEEK tube are placed above the hot end tip. These prevent heat from the hot end to transfer backwards and melt the material even before it enters the hotend tip. As the melting temperatures of PTFE & PEEK tubes are around 230 degrees centigrade, for all metal hotends, steel tubes are placed in place of these tubes. During the printing process, suddenly the printer stops extruding material and starts printing in the air. When examining the hotend, it is found that the hotend got clogged/jammed and the extruder fan was not running while the printing is in progress.
Action: When using an all metal hot end, cooling system is mandatory. Cooling fan pushes air on to the steel tube mentioned above. This absorbs the heat from the steel tube and keeps the temperature at the steel tube lower than the melting temperature of the filament. By doing so, the filament is maintained in a semi-solid state till it reaches hot end tip which is very essential for the extruder gear to pull down the filament till the reaches the tip. If the cooling fan isn't present, due to the very low vitreous transition temperature, if the plastic gets hot enough in the hot end, it might jam there. Almost all hotends require a fan. Also, when printing relatively small parts, the plastic doesn't have time to cool down and expand more than it should every time a new layer is added. In other words, more heat gets into the part than it can dissipate. Adding a fan to blow the part helps the part cool faster.