Bending and forming PLEXIGLAS®: thermoforming in just a few steps

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

PLEXIGLAS® can be formed into almost any shape, all it needs is some heat. Discover the various methods for easy thermoforming (also known as “bending”) of acrylic sheet.

    • Prepare a mold
    • Don’t use a flammable base
    • Remove protective film
    • Switch on infrared radiator
    • Heat the PLEXIGLAS® sheet
    • Bring PLEXIGLAS® into the desired shape
    • Allow it to cool slowly

Materials and tools—thermoforming PLEXIGLAS®

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt
  1. Infrared radiator
  2. Nonflammable material, such as aluminum sheet, as a base
  3. Stop bar
  4. Cover plates, e.g. of aluminum, for linear heating
  5. Wooden spacers for linear heating
  6. Weights
  7. Mold of wood, metal, or casting resin
  8. Cotton cloth
  9. PLEXIGLAS® Sheet
  10. Clamps

Heating PLEXIGLAS®: More than one way

In particular temperature ranges PLEXIGLAS® can exist in various states of matter: solid, thermoelastic, or thermoplastic. This offers the advantage that you can easily form PLEXIGLAS® and give it a wide variety of shapes. Various possibilities exist for heating a PLEXIGLAS® sheet and then forming it:

  • in air-flow ovens,
  • by infrared radiation,
  • with hot plates

Heating with infrared radiators is one of the most commonly used variants; specialist processors may use the other methods. More information is available in our brochure Forming of PLEXIGLAS® (see section 2, Heating).

Regardless of which of these options you choose, you can heat either the entire surface of the acrylic sheet or just a particular area, where the sheet is to be line-bent, for example. There are two methods for this:

  • surface heating and
  • linear heating.

HOW-TO-VIDEO: SURFACE HEATING AND LINEAR HEATING


Instructions for surface heating of PLEXIGLAS® with infrared radiator

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

1

Prepare the mold

Prepare the mold in advance so that acrylic sheet can be formed into the desired shape immediately after heating. Suitable mold materials are wood, laminates, metals, and casting resins. Wooden molds in particular are inexpensively produced and easy to repair and, if necessary, modify. To prevent mark-off on the sheet, you can cover the mold with a soft stretchable cotton cloth.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

2

Prepare the workplace

Lay a fireproof base, such as of aluminum, on the work surface. Cover the base with a cotton material to prevent marks or scratches.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

3

Remove protective film

Check whether there is a protective film on the PLEXIGLAS® sheet. If so, you should remove it; otherwise there is a risk that the film will adhere to the surface too strongly and can no longer be stripped off after cooling.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

4

Switch on the infrared radiator

Switch on the radiator and wait until it has warmed up. For bright radiators this is the point at which they glow cherry red.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

5

Heat the PLEXIGLAS®

Place the PLEXIGLAS® sheet under the infrared radiator to heat it. The correct distance between the radiator and the acrylic sheet depends on the radiator and the material thickness. You preferably should determine this distance beforehand, using a test piece. The thicker the sheet, the longer it needs to be heated. If the material is heated on one side only, it will initially curve upward. After a while the sheet will flatten again; this indicates that it is now hot enough to be formed. If the sheet is thicker than 5 mm, it should be turned occasionally to heat it evenly and to rule out overheating of the surface.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

6

Forming PLEXIGLAS®

Form the PLEXIGLAS® sheet - depending on the desired shape, use the prepared mold. Make sure the material is hot.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

7

Allow PLEXIGLAS® to cool

Let the molding cool slowly and wait until it has attained sufficient dimensional stability before processing it further. This is the case when the material is warm to the touch. Avoid drafts during cooling. Tip: To help the material cool evenly, cover it with a cotton cloth.


Instructions: Linear heating of PLEXIGLAS® with infrared radiatorTSTRAHLER

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

1

Prepare the mold

Prepare the mold in advance so that the PLEXIGLAS® sheet can be formed into the desired shape immediately after heating. Suitable mold materials include wood, laminates, metals, and casting resins. Wooden molds in particular are inexpensively produced and easy to repair and, if necessary, modify. To prevent mark-offs or scratches on the sheet, you can cover the mold with a soft elastic cotton material.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

2

Prepare the workplace

Lay a fireproof base, such as of aluminum, on the work surface. Cover the base with a cotton cloth to prevent mark-offs and scratches. Place wooden spacers on the base and two cover plates, e.g. of aluminum, on top of them. Only the place where the heat from the infrared radiator is subsequently to be directed on to the sheet must remain free. The distance between the cover plates must be three times as great as the material thickness.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

3

Remove protective film

Check whether there is a protective film on the PLEXIGLAS® sheet. If so, you should remove it; otherwise there is a risk that the film will adhere to the surface too strongly and can no longer be stripped off after cooling.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

4

Switch on the infrared radiator

Place the infrared radiator on the base, switch it on, and wait until it has warmed up. For bright radiators this is the point at which they glow cherry red.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

5

Heat the PLEXIGLAS®

Place the PLEXIGLAS® sheet under the gap that has been left free between the cover plates to heat the acrylic. The right distance between the radiator and the acrylic sheet depends on the radiator and the material thickness. If possible, determine this distance in advance, using a test piece. In the covered region the material surface is not heated, so that the stiffness required for line bending is retained. The thicker the sheet, the longer it needs to be heated. If the material is heated on one side only, it will initially curve upward. After a while it subsides again; this indicates that it is now hot enough to be formed. For one-sided heating, it is advantageous to turn the sheet after a certain time. To find the same position, it is advisable to work with a stop bar.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

6

Forming PLEXIGLAS®

Place the sheet in the mold to obtain the desired angle.

© Röhm GmbH – Acrylic Products / Photo: Stefan Wildhirt

7

Allow PLEXIGLAS® to cool

Let the molding cool slowly and wait until it has attained sufficient dimensional stability before processing it further. This will be the case when the material feels warm to the touch. Avoid drafts during cooling. Tip: For uniform cooling of the sheet, it is recommended that the sheet be covered with a cloth and also weighted with a weight.


Tips and tricks for thermoforming of PLEXIGLAS®

  • Peel off the protective film from the four corners, working toward the center, to prevent dust on the PLEXIGLAS® sheet.
  • Ensure that your workplace is as clean as possible.
  • Wear protective gloves to avoid injury.
  • If you are cleaning the sheet surface with compressed air, wear safety glasses.

Further topics

Sanding and polishing PLEXIGLAS®

Sanding and subsequent polishing lets rough, matt PLEXIGLAS® cut edges and surfaces appear glossy again, even scratches can be removed in this way. This guide describes the procedure as well as the tools suitable for the purpose.

Bonding PLEXIGLAS®

PLEXIGLAS® parts are easily joined to one another. This guide tells you how to bond PLEXIGLAS® and which adhesives are suitable.

Drilling PLEXIGLAS®

PLEXIGLAS® is drilled as easily as wood a few special properties must be factored in, however. Find out which drill bits are suitable for PLEXIGLAS®, how to drill and what to look out for during the process.

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