| Innovative Custom Thermoformed Solutions |
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By definition, thermoforming is the forming or molding of heated plastic after the application of vacuum or air pressure. Vacuum is used to evacuate air between the heated sheet and the mold and may be assisted by positive air pressure to enable the sheet to conform to the contour of the mold. In some cases, various secondary operations are necessary to finish a thermoformed part. These secondary operations may include:
The advantages of thermoforming include significantly lower tooling costs and lead times when compared to injection molding or other closed cavity methods as well as shorter cycle times and increased throughput on larger parts when compared to rotational molded parts.
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Hampel capabilities include the three basic thermoforming processes most widely utilized. These processes include vacuum forming, pressure forming and twin sheet forming.
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| Vacuum Forming Vacuum forming is the basic process in which vacuum evacuates the air between the heated sheet and the mold. This enables atmospheric pressure to force the sheet against the mold and conform to its contour. |
| Pressure Forming Pressure forming, like vacuum forming, also requires evacuation of air in the forming process. In addition, pressure is applied to the opposite side of the heated sheet causing it to conform more precisely to the contour of the mold. This additional pressure allows the formed part to take on the intricate detail incorporated on the mold. Pressure formed parts maintain the detail and appearance of an injection molded part with considerably less tooling costs. |
| Twin-Sheet Forming Twin-sheet forming, just as it sounds, is the synchronized vacuum forming of two separate thermoplastic sheets in separate matching molds mounted opposite to each other. The molds are brought together while the formed sheets are still hot allowing them to fuse or weld together in strategic areas. Compressed air is then injected between the two welded sheets forcing the part to remain conformed to the contours of the mold and cooling the now sealed hollow cavities of the formed part. Twin sheet parts take on the characteristics of rotationally molded or blow molded parts but have distinct advantages in design flexibility and tooling costs. |
| Common Thermoformed Materials |
| ABS – Acrylonitrile Butadiene Styrene |
| HIPS – High Impact Polystyrene |
| HMWPE – High Molecular Weight Polyethylene |
| PP – Polypropylene |
| TPO – Thermoplastic Olefin |
| Solarkote® – An acrylic capstock that is co-extruded over ABS to provide weather resistance and chemical resistance while providing a cosmetic appearance |
| WeatherPro-G®– A tri-layer extruded material consisting of an acrylic cap for gloss and cosmetic appearance, a weather resistant ABS layer and an ABS substrate |
| Altair Plus®– A composite engineered material that has a continuous cast acrylic surface with a high-impact ABS substrate for added strength. The acrylic surface provides proven weathering characteristics and high cosmetic appealLinks |
| Educational Links |
www.milwaukeespe.org |