ANNEALING OVENS AND FURNACES
Despatch offers a wide selection of high performance ovens designed for annealing
applications. These ovens feature a variety of chamber sizes and temperature
capabilities, as well as exceptional temperature uniformity, flexibility and tight process
control and monitoring.
Despatch’s high performance annealing ovens are used around the globe within a
variety of industries, including technology, transportation, healthcare and industrial
Annealing is the most commonly used for treating metals, but other materials, including glass and plastics, can be
annealed. Depending on the material, annealing temperatures range from less than 100 degrees C to more than
1000°C., a process that can take hours or several days.
During the annealing process, a metal, plastic or glass is heated to a specifi c temperature or color and then the metal is
cooled at a controlled, specifi ed rate. This process changes the physical and chemical properties of the material to make
it more malleable, or improve ductility; provide stress relief and create a new microstructure.
A specialized annealing oven gives users the ability to tightly control and monitor the heating and cooling process,
allowing for proper recrystallization to occur within the material. The materials are annealed at the eutectic point and then
allowed to cool. Annealing often softens the materials so they can be shaped or cut more easily, but can also increase its
strength and ductility. Metals are often annealed to prepare them for further heat treatments.
The environment; temperature maintained, both during and
after the annealing process; and cooling rate are critical.
Typical temperatures used in heat treating the most common
Steel – 150°C to 1232°C
Stainless Steel – 345°C to 400°C
Aluminum – 90°C to 775°C
Copper – 120°C and up to 800°C
Plastics – 77°C and up to 260°C
Annealing is not required in all plastic molding; some stresses can be eliminated without the
annealing process, depending on the design and materials.
Annealing plastics is recommended based on the following conditions:
- If the end-use conditions are demanding enough to require stress relief beyond
what can be achieved through the product design, process and materials.
- If stress relief after machining is necessary.
- If during the post polishing process the material would likely crack due to surfaces
stresses caused by the polishing itself.
These are usually non-uniformed stresses that
can lead to premature failure.
Advantages of Annealing Plastics
Plastics that have been stress relieved offer:
- Tighter tolerance
- Improved chemical resistance
- Improved wear resistance
- Improved flatness control
- Better able to handle machined stress
Plastics require different annealing conditions and temperatures:
- Polycarbonate: 250°F(121°C) for as short a time as possible determined through experimenting with test data
- Ultem: slowly brought up to 400°F(204°C) and then held for two hours
- ABS materials: heat deflection temperature at 264 psi (170°F to 240°F) and held for 1-2 hours.
- Supec resins: Annealed at 400°F(204°C) for 4 hours
Custom Annealing Ovens
Despatch designed and built a custom FCH2-12 furnace for a special component annealing application. Per the
customer’s request, the FCH incorporated HEPA filtration of fresh air and a 316L interior for improved chamber
cleanliness. Other features included modulating dampers on the fresh air and exhaust to
allow a controlled cooling rate and a large forced exhaust fan to promote rapid cooling
after a cycle. A Watlow F4 controller with WatView software was provided to support a
variety of cycle profiles with a highly flexible profiling controller.
The FCH2-12 furnace is available with standard design features including 1350°F (732°C)
maximum temperature rating, 7 inches of layered insulation, 304 stainless steel fully
welded interior, horizontal airflow with adjustable supply and return louvers and a 5 HP
recirculation drive motor. The oven is capable of temperature uniformity of ±1% or better
after stabilization. This oven is compatible with a variety of high temperature processes.