How a High-Pressure Forming Machine Works: Lower Mold Only, Formed by Gas
A high-pressure forming machine has no upper mold: the film is heated to its softening point, the mold closes, high-pressure air is applied in stages from above while vacuum is drawn below. Ideal for PC/PMMA cosmetic parts.
Unlike a matched-die hot press, a high-pressure forming machine has no upper mold, only a lower mold. High-pressure gas presses the heat-softened sheet directly onto the lower mold.
Forming sequence
- Heat the film to its softening point.
- Close the mold.
- Apply high-pressure air in stages from the upper chamber while drawing vacuum in the lower chamber.
- The film conforms fully to the mold, cools and is removed.
Why it suits PC/PMMA composite sheet
PMMA/PC composite sheet meets rigidity and decoration needs and also suits wireless charging because it does not shield signals: PMMA gives hardness and weather resistance, PC gives impact strength and formability.
PC/PMMA is an optical-grade, highly transparent material. On cosmetic parts such as battery covers, the UV texture and sputtered finish on the PC side must stay flawless. Air is a soft pressure that acts equally on every surface in the closed cavity, so the visible surface never touches an upper tool and is not marked.
Equipment: AS201F-G high-pressure gas forming machine, IMD high-pressure forming machine. Further reading: IMD/IML thermoforming machines: process and applications.
Adapted from an article published on SANSEN's original Chinese website (sansendg.com) on 2022-09-27. The text was edited and restructured; technical content follows the original.