Why Choose a Non-Continuous Furnace?
Manufactured items frequently undergo heat treatment at some stage of the manufacturing process. A furnace is a high-temperature chamber capable of holding glass, metals, ceramics, and other materials so that heat may be applied to achieve desirable results.
Although all furnaces apply heat, there is a variety of furnace designs that fulfill a wide range of manufacturing requirements.
Many manufacturing processes, for example, require discontinuous heating and cooling. Vacuum furnaces are one type of non-continuous furnace design that eliminates airborne contaminants prior to treatment. Optimum conditions are easier to sustain in a closed process system, such as a non-continuous furnace.
What is a Non-Continuous Furnace?
In contrast to the conveyor belt approach used in a continuous furnace — where parts are heated evenly and processed sequentially — a non-continuous furnace treats parts individually, often in batches (hence the term batch furnace). Such a furnace offers the flexibility in formulation that is required in specialized (or high precision) applications.
A non-continuous furnace is a closed process machine best suited for inert atmosphere or cleanroom applications. Once the heating chamber has been sealed, heat treatment can be performed without risk of cross-contamination.
In batch furnace heating, items are grouped in racks or baskets for treatment. Rather than being automatically fed into the heating chamber, articles need to be removed from the production line for grouping. This requires more work, but this is offset by batch furnaces’ ease of operation (and maintenance).
Continuous furnaces are more complex (and therefore more expensive) than batch furnaces. As such, they require frequent maintenance. In continuous furnaces, temperature uniformity is critical such that temperatures cannot be easily altered. A non-continuous furnace allows for flexibility of formulation — free of cross-contamination — in specialized applications in aerospace, automotive, petrochemicals, optics, and other industries.
Benefits and Applications of a Non-Continuous Furnace
A non-continuous furnace is suited for applications that require a range of operating temperatures and heating times. In this type of furnace heating, temperatures can be adjusted between batches. Also, because non-continuous furnace systems are not constantly heated, they can achieve higher temperatures when compared to continuous furnaces.
Several heat treatment processes are performed in a controlled atmosphere, such as brazing, annealing, tempering, carburizing, and sintering. In critical applications, controlled atmospheres promote the production of clean parts while preventing unwanted reactions (such as decarburization and oxidation) from occurring on the surfaces of these parts.
Air, for instance, is a gas containing oxygen, carbon dioxide, hydrogen, nitrogen, and water. At room temperatures, these elements react too slowly with surfaces to be of any concern. However, at the elevated temperatures operating in furnace systems, they may interfere with the manufacturing process.
Vacuum furnaces are a type of non-continuous furnace design that addresses this issue. In vacuum furnaces, the air is removed from the furnace chamber prior to heat treatment. Besides removing surface contaminants and preventing unwanted reactions, vacuum treatments can also be used to degas and join metals.
At the end of the treatment, an inert high-pressure gas such as helium, argon, or hydrogen is injected into the furnace chamber to cool parts under treatment. Hardening, tempering, and brazing are some processes performed in vacuum furnaces.
A vacuum furnace may be used to manufacture, among others:
- Airframe, hydraulic, and engine parts in aircraft
- Nuclear reactor components
- Vehicle parts such as gears, suspension, steering, injectors, and camshafts
- Fasteners such as superalloy and construction bolts, and medical fasteners
- Medical equipment such as surgical instruments, artificial hips, knees, and joints
- Tools and household items
A non-continuous furnace ensures the quality and performance of manufactured parts while conforming to health and safety standards. Such a furnace design reduces the occurrence of part rejection and saves costs.
Custom Tunnel Kilns by Deltech
A custom tunnel kiln might constitute an ideal alternative to a bottom-load, front-load, or top hat Deltech non-continuous furnace. With an operating temperature reaching 1800oC — and an option to add controlled atmosphere capability — a custom tunnel kiln by Deltech is the ideal way to scale while replicating the benefits of resistance-heated batch furnaces.
References
- OpExWorks. Types and Classification of Different Furnaces. [online] Available at: http://www.opexworks.com/KBase/Energy_Management/Termal_Energy_Management/Furnaces/Types_and_Classification_of_Different_Furnaces.htm
