Hot bending of plastics: techniques, materials and applications 

Hot bending is a flexible and efficient processing method for thermoplastics where the material is shaped by controlled heating to the softening temperature. The technique enables both simple and complex geometries, and is well suited for everything from prototype manufacturing to series production.

What is it? 

Unlike cold bending, which relies on the elastic deformation of the material, hot bending is based on heating thermoplastic material to its softening temperature, usually between 80°C and 160°C depending on the type of plastic, and then forming it mechanically. After forming, the material is held in position until it cools and assumes its new geometry permanently. 

Thermoplastics

  • PMMA (acrylic): Offers high dimensional stability and optical clarity, but has limited impact resistance and can crack under mechanical stress.
  • PETG: Combination of good impact resistance and flexibility. Easy to shape at low temperatures without losing transparency or strength.
  • PVC: Available in both rigid and soft grades. Distinguished by chemical resistance, dimensional stability and formability at moderate heat.
  • PC (polycarbonate): Extremely impact-resistant with high mechanical strength, but sensitive to internal stress formation when overheating.

Techniques

1. Hot wire line bending: The most commonly used technique for flat sheet materials. An electric wire heats the plastic locally along a line until it becomes bendable. Often used for manufacturing machine guards, displays, and enclosures in short runs. The angle is adjusted manually or with jigs.

2. Oven forming: Used for larger or multi-dimensional geometries. The entire workpiece is heated in a heating oven (approximately 120–150°C), formed over templates and cooled in shape. Common for e.g. dome-shaped covers or complex packaging.

3. IR-based hot bending: Infrared heating offers fast, contact-free heating. The technology is particularly effective for automated bending of thinner materials, such as blister packaging or POS displays.

4. Mold bending in press tools: Here, a heated tool (mold and counter mold) is used to shape the plastic under controlled pressure. The method combines heating and mechanical bending in one step and is suitable for series production.

Advantages compared to other methods 

  • Possibility of shaping without joints or adhesive joints
  • Low tooling cost compared to injection molding
  • Suitable for both prototypes and series production
  • Low residual stress in the material when cooled correctly
  • Quiet and clean processing – suitable for hygienic environments 

Quality assurance and post-processing 

This method requires precise temperature control, even heat distribution and proper fixation during cooling. Post-processing can include chamfering for better fit, CNC milling for tolerance adjustment and installation of fasteners or seals.  

In critical applications, each batch should undergo visual inspection and dimensional verification against CAD data. Plastics processing is often covered by regulations such as REACH and CLP for chemical handling, as well as standards such as ISO 178.

Closing reflection 

With the right material selection, temperature control and a well-thought-out process, hot bending can deliver plastic components with high dimensional accuracy and long-lasting performance. For manufacturing companies, a deeper understanding of its technical capabilities provides increased process control, efficiency and design freedom. 

Would you like to know more about how the method can streamline your production? Visit our page for hot bending to read more about the technology, material choices and how we adapt the process to your needs. Please contact us for advice or a quote request.