This disclosure relates to the field of safety in electrical heaters that use Magnesium Oxide as isolator
between live and ground.
A process is disclosed that removes the moisture absorbed by the strip heaters by using a heating
system, without powering on the three‐dimensional build unit, to avoid potential safety users’issues
caused by electrical arcs in the build unit.
Some three‐dimensional printing build units use strip heaters technology. The electrical isolation of the
strip heaters is made using Magnesium Oxide (MgO) which is a hygroscopic solid material which absorbs
humidity from the surrounding environment arising moisture on the strip heaters.
The moisture in the strip heaters makes that their resistance drops till levels around 2‐3MΩwhen it is
supposed to be infinite or beyond 10 MΩ
When full voltage is applied to a moisture laden heater it could arise that fuses blow, circuit breakers
trip, and voltage arcs to the sheath, destruction of the heater or user safety and integrity.
The method described in this disclosure solves the issue by using the Heating System of the 3D printer
by creating an initial pre‐heating process without the need of electrically connecting the BU and
removing moisture to make the machine safe for the user and not compromise the integrity of the
This method was validated in different Build Units that had moisture issues and it was demonstrated
that the machine could be used safely without any concern.
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INC, HP, "BUILD UNIT'S STRIP HEATERS MOISTURE REMOVAL METHOD BY USING HEATING TECHNOLOGY", Technical Disclosure Commons, (May 01, 2020)