A thermo-FORM-ula for processing success
Thermoforming: Where heat & pressure come together
Thermoforming involves forcing heated thermoplastic sheet against a mold to produce the desired shape. As the thermoplastic cools, it retains the detail of the mold which formed it. It is an economical and practical processing method for producing large parts in particular for the mass transit and medical markets, architectural glazing, signage and spas.
Thermoformed bezel made of Bayblend® FR3030 (PC+ABS blend) for the BreezeDry appliance
Thermoforming of extruded sheet is an economical process for producing medium to very large parts. Because relatively low pressures are required to produce thermoformed parts, the forming molds are less expensive than injection molds and are typically produced from aluminum.
A basic thermoforming process begins by heating a clamped sheet and sealing it, to a mold. If pre-stretching is required, it is accomplished with a partial vacuum, air pressure, or plug assist. Then, while the sheet is still within the proper forming temperature range, vacuum and/or air pressure is applied to form the sheet onto or into the mold. In some cases, matching male and female molds come together to help form the sheet. The sheet is held fast to the mold while the part cools. After the part has sufficiently cooled, it is removed from the mold, either manually or with automatic ejection systems, followed by any necessary secondary operations, such as trimming or decorating. The process is then repeated for the next sheet.
Mold design is the most important factor in thermoforming success. Well-designed molds promote consistent quality in finished parts. Covestro offers expertise in thermoforming mold design, including utilizing T-IMS thermoforming simulation software.
Covestro offers several polymer grades that can be converted to sheet or film for thermoforming. These include Makrolon® polycarbonate, Bayblend® (PC+ABS; PC+ASA blend) and Makroblend® (PC+PBT; PC+PET blend) resins.