Annealing plastic: the principle for increasing the resistance of plastic
Annealing refers to the heat treatment of plastics for the reduction of mechanical tensions as well as the targeted modification of the microstructure. When producing and joining plastic components, material tensions can arise. This not only reduces the quality and life of the finished product, but can lead to a functional impairment or complete failure in an emergency. Last but not least there is an immense risk of injury in splintering plastic containers or Plexiglas panes. During annealing, the increased temperature enhances the mobility of the atoms, thereby compensating for structural defects and improving the crystal structure. Many thermosetting plastics such as resins and adhesives require heat to cure. The supply of heat, which serves for the phase transformation from liquid to solid, is called hardening or annealing/tempering.
Infrared radiation as an optimal heat source for annealing plastics
For the provision of heat during the annealing process, infrared radiators are outstandingly suitable, since they have a high power density and a specific controllability. This ensures a systematic annealing or hardening process. The non-contact temperature measurement by means of a pyrometer and the control of the heater output according to the setpoint temperature ensure an optimized process flow. Due to the direct and targeted heat input infrared radiation heats the component only where it is required. This saves energy and time.
What has to be considered in the case of plastic annealing?
The higher the temperature of a material, the more internal energy it has to break down or cure mechanical tensions. However, the temperature must not reach or exceed the material-specific melting point. In addition, a uniform annealing process within a component requires homogeneous heating. The optimized arrangement and alignment of the infrared radiators, combined with a temperature control, ensures this automated and process-reliable annealing process.
The advantages of infrared radiation for plastic annealing at a glance
- High heat flux density, heating within seconds
- Direct heat transfer without contact to the material
- Targeted applications: large surfaces can be heated as well as small sections or curved parts
- Economic operating mode
- Low energy loss
- High efficiency
- Easy and safe operation due to defined temperature control and ramp functions