When does a screen solve a uniformity problem?

When the temperature difference is caused by direct view between the load and the elements, or between the load and a cold zone. If the deviation comes from control, installed power, or insulation, a screen will not correct it.

Solid graphite screen or felt?

Solid graphite machines to a precise shape, withstands handling, and works as a structural baffle; felt insulates more with less mass and is quick to cut. The choice depends on whether the part must support itself and be positioned accurately.

Are screens stacked in several layers?

In radiation shielding it is common to use several layers separated by a gap, because each layer reduces exchange with the next. The number of layers and their spacing are part of the chamber thermal design.

What is needed to manufacture a custom screen?

The intended function, the position inside the chamber, temperature and atmosphere, and the drawing or dimensions. That defines material, thickness, and fastening system.

Thermal applications

Furnace thermal shields

Graphite or felt shields, screens, and baffles for thermal radiation control in furnaces and vacuum chambers.

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Thermal radiation control element

Also known as: Graphite thermal screens · Furnace heat shields · Radiation baffles · Graphite baffles

Graphite/felt thermal screens and shields to protect the load and improve thermal uniformity.

[ Technical summary ]

At high temperature, heat transfer inside the chamber is dominated by radiation, and an interposed screen changes that path. Graphite or felt shields, screens, and baffles are placed between the heating elements and the load, or facing cold zones, to prevent local overheating and improve uniformity. Being machined or cut to size, their shape is matched to the heat distribution sought in each furnace.

Thermal shields and screens direct or block radiation inside the furnace. They are made from machined graphite or felt (soft/rigid) depending on temperature, vacuum, and stiffness needs.

[ Problem it solves ]

Redirect or block thermal radiation inside the chamber to correct hot spots on the load and losses toward zones where the heat is not useful.

Operating conditions

Radiative thermal shielding
Vacuum and heat-treatment furnaces
Protection of cold or load zones
Thermal uniformity improvement

When it is suitable

The load shows local overheating facing the elements
There are radiation losses toward doors, feedthroughs, or cold zones
Uniformity must improve without redesigning the hot zone
The furnace works in vacuum or inert atmosphere

When it may not be suitable

The process runs in air at high temperature without a protective atmosphere
The screen would obstruct gas flow or access to the load
The thermal problem comes from furnace control rather than radiation

Process challenges

Local overheating of the load
Radiation losses toward walls
Contamination or uneven shadowing

Advantages

Radiative heat-flow control
Geometries machinable in graphite or cut from felt
Compatible with vacuum and inert atmospheres

Limitations

Design depends on chamber thermal optics
Oxidation in air at high temperature
Must be coordinated with heating elements and insulation

[ Critical selection variables ]

These variables define the grade and the geometry. Actual values are confirmed against the grade datasheet.

Thermal radiation pathDecisive
Operating temperatureDecisive
Geometry and tolerancesDecisive
Atmosphere (air, inert, vacuum)Relevant
Gas flow and compositionRelevant
Fastening system and jointsRelevant
Thermal and duty cyclingRelevant

[ Required material properties ]

Properties that guide selection. Numerical values come from each grade's datasheet.

Critical properties

Thermal conductivity
Thermal shock resistance
Purity
Thermal stability

Secondary properties

Dimensional stability
Machinability

[ Related ]

[ Frequently asked questions ]

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Technical content reviewed by ESGRAF — Last reviewed: September 8, 2026

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