Some 3D Printing technology heavily depends on the internal printing conditions in the
Printing Chamber. One of the most important variables are temperature and pressure.
The first permits to have temperature in a narrow range in order to have powder surface
at constant conditions for printing process. Pressure and pressure distribution inside the
chamber permits defined airflows within this cabinet.
Energy sources may include Fusing Lamps and Top Lamps. As the powder itself has a
particular reflectance, not all the energy is absorbed, but reflected inside the printing
chamber. Additionally, there are other heat sources in order to keep the powder in Print
Bucket at the desired temperature, for instance. Globally, there is an excess of energy
that needs to be removed from the Printing Chamber.
In terms of internal pressure, there are several objectives. The first is to have a defined
over- or under pressure with respect to ambient conditions to obtain a global stray flow
(due to lack of sealing) towards the Printing Chamber or from the Printing Chamber
towards environment respectively. Second, the control of internal pressure distribution
makes possible to have a preferred direction of airflow towards a desired area, which
leads to higher thermal homogeneity if defined correctly.
In order to remove excess heat from the Printing Chamber, gas circulation is commonly
used. It can be made with an open or closed circuit. When the gas is air, usually open
circuit is used; contrarily, when the gas is for example an inerting gas, the circuit is
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INC, HP, "CONSTANT PRESSURE VALVE TO COMPENSATE EXTRACTION SYSTEM PRESSURE VARIATIONS", Technical Disclosure Commons, (December 23, 2019)