Design Of A Vacuum Thermoforming Device And Experiments On Pin-Tool Type Reconfigurable Surfaces

Thermoforming is a manufacturing process in which a thermoplastic material is heated and pulled over a mold to form a product. Examples of thermoformed articles include clamshells, refrigerator door panels, and automobile components. While thermoforming is a versatile and useful procedure itself, the tooling is not easily adaptable. The creation of molds is expensive and time consuming, and each one can only generate a specific shape. A reconfigurable mold would reduce expenses while increasing functionality (and leveraging the advantages of vacuum thermoforming). Specifically, in this research project, a self-inclusive thermoforming device was designed and constructed with a pin-type tool reconfigurable mold fitted in. The pin-tooling consists of a ten by ten matrix of height-adjustable pins with hemispherical tips. Though pin-tooling is less costly and more variable, there are other challenges, found in attaining a high quality surface finish and accurately producing a desired surface shape. To explore and address these challenges, experiments were devised with various configurations of the pin-tooling, including variable sheet materials and material thicknesses, different surface shapes, changes in plastic temperature, heating time of plastic, orientation of the pin-tool, and variation of interpolators. Initial results indicate the importance of the distance from the heating element to the plastic, that the materials’ stretch limits act as a minor interpolator, that the taller drops the plastic has to mold over require higher heated and/or more flexible material, and the orientation of the pins relative to the vacuum mouth is significant