One of the easiest ways to categorise thermal processing equipment is by configuration. It is not uncommon to classify furnaces by application (i.e., pharmaceutical ovens), or even by specific certifications (i.e., ISO 6245-accredited), but using the general shape and orientation of the heating chamber is the preferred naming convention. This is for simplicity’s sake, as users can derive plenty of information from whether a prospective solution is a box or a tube furnace. But when should you use one or the other?
This article will discuss the basics of horizontal tube furnaces and explore some of the potential use cases where they offer the best-in-class performance.
What is a Horizontal Tube Furnace?
A horizontal tube furnace is an electric thermal processing solution with a characteristic heating chamber comprised of a continuous piece of high-temperature insulation, or two semi-cylindrical elements. They are often consequently defined as either solid or split tube furnaces.
In either type, the term horizontal refers to the orientation of the cylinder length. There is typically a central hot zone (or zones) and accessible end or top plugs that may protrude from the furnace body for easy access to the processing chamber. This configuration is most common in solid tube furnaces, as split tubes provide access to the recessed chamber by hinging open.
Furnaces designed for use at 1200°C or less feature wire wound refractory metals heaters. These are typically embedded into the insulated chamber walls to maximise space and thermal uniformity. Furnaces designed for higher use temperatures feature either silicon carbide or molydisilicide heating elements suspended from the furnace roof in arrays along both sides of the tube.
Benefits of Horizontal Tube Furnaces
Now that we have recapped the basics, let us look at the main benefits of horizontal tube furnaces and how they enable leading-edge performance in specific application areas.
Unmatched Thermal Uniformity
The primary benefit of tube furnaces is their unmatched thermal uniformity. Workpieces in the hot zone are subjected to sustained temperatures of up to 1800°C (3272°F) across their full 360° axis. This guarantees completely consistent heat distribution throughout the chamber and thus across the total cross-section of the workpiece. Any small batch production process of thermally sensitive parts benefits from the outstanding uniformity of tube furnaces.
In a typical horizontal tube furnace, the central portion of the cylinder comprises the heating zone. A controlled thermal gradient spans to either end of the tube. Several options are available based on single and multi-zone cylindrical heaters, maximising end-usability. You can choose a single zone heater with water cooled end caps for optimal thermal uniformity in the smallest possible format. Or use a multi-zone tube furnace with fully definable temperature programmes for precise control of heating and cooling. With easily accessible end caps, this makes tube furnaces ideal for small scale materials tests.
With optional gas mixing and delivery systems, horizontal tube furnaces are ideal for thermal process with strict atmospheric requirements. Heating can be carried out under inert or reducing conditions, with precise mass flow controllers and programmable alerts supporting a range of important safety features. This is crucial for users across the full spectrum of lab and factory-based thermal processing.
Horizontal Tube Furnaces from Deltech
At Deltech Furnaces, we supply a range of horizontal tube furnaces designed for heat treatment of relatively small samples with strict atmospheric and thermal requirements. Refer to our horizontal tube furnaces product page or contact us for more information.