Thermoforming
“Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product. The sheet, or "film" when referring to thinner gauges and certain material types, is heated in an oven to a high-enough temperature that it can be stretched into or onto a mold and cooled to a finished shape.”
“In its simplest form, a small tabletop or lab size machine can be used to heat small cut sections of plastic sheet and stretch it over a mold using vacuum. This method is often used for sample and protoype parts. In complex and high-volume applications, very large production machines are utilized to heat and form the plastic sheet and trim the formed parts from the sheet in a continuous high-speed process, and can produce many thousands of finished parts per hour depending on the machine and mold size and the size of the parts being formed.”
“There are two general thermoforming process categories. Sheet thickness less than 1.5 mm (0.060 inches) is usually delivered to the thermoforming machine from rolls or from a sheet extruder. Thin-gauge roll-fed or inline extruded thermoforming applications are dominated by rigid or semi-rigid disposable packaging. Sheet thicknesses greater than 3 mm (0.120 inches) is usually delivered to the forming machine by hand or an auto-feed method already cut to final dimensions. Heavy, or thick-gauge, cut sheet thermoforming applications are primarily used as permanent structural components. There is a small but growing medium gauge market that forms sheet 1.5 mm to 3 mm in thickness.”
( Wikipedia, Thermoforming, 7/23/2010)
Polyesters for Thermoforming
Polypropylene (PP) for Thermoforming
Processing
Shape Memory Thermoforming
Thermoforming Composites
Thermoforming Manufacturing
Trimming Thermoformed Structures
Twin-Sheet Thermoforming
Vacuum Thermoforming
Recent US Patents
9/7/2010
7,790,274
Layered panel structure including self-bonded thermoformable and non-thermoformable layer materials
Monk and Hicks of High Impact Technology formed a multilayered panel by thermoforming a thermoplastic sheet to a non-thermoformable layer such as balsa wood. (RDC 11/30/2010)
Recent Journal Articles
Sheet temperature in thermoforming
(293-330) Journal of Plastic Film and Sheeting 27 #4 (2011)
Abstract
Michaud and Giacomin of Bemis Company and the University of Wisconsin – Madison, Wisconsin derived the heat flux distributions over both faces of a bowing or sagging sheet, along with the corresponding temperature profiles through and across the bowing or sagging sheet. These predictions can help plastics engineers to present a sheet of uniform temperature to a thermoforming mold. (RDC 10/12/2011)