What is Thermoforming?
- Thermoforming is the process of heating thermoplastics to their forming temperature and drawing them over a mold cavity wherein it takes on three-dimensional characteristics. Thermoforming has a wide range of applications.
- Thermoforming is grouped into two categories depending on the sheet thickness of the formed part: thick gauge thermoforming (0.125" – 0.500") and thin gauge thermoforming (less than 0.060").
- The first step in the thermoforming process is heating of a plastic sheet to its forming temperature. The forming temperature is arbitrary to most manufacturers.
- Forming stages gives the three-dimensional characteristics (length, width, and height) to the once flat sheet. Forming methods may be vacuum forming, pressure forming, mechanical forming and twin sheet forming. Afterwards, formed parts are trimmed from the sheet web.
- Thermoplastics in the form of sheets are the starting material of the thermoforming process. These plastics can survive cycles of heating and cooling, allowing them to be recycled. Thermoplastics may be amorphous and semi-crystalline.
- Forming temperature is the temperature above the glass transition and below the melting temperature.
- The mold may be a positive or negative tool, and its material significantly affects the heat transfer across the sheet.
- Parameters to be optimized and controlled are forming temperature, mold tool temperature, vacuum and/or air pressure, and liquid and/or air coolant temperature.
- Proper tool management and temperature control is the key to successful thermoforming.