Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape on 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. Vacuums are applied to the heated shape assuring a tight and uniform fit to the mold.

In its simplest form, a small tabletop machine can be used to heat small cut sections of plastic sheet and stretch it over a mold using the vacuum. This method is often used for sample and prototype parts.

Thermoforming differs from injection molding, blow molding, rotational molding, and other forms of processing plastics. Thick-gauge thermoforming includes parts as diverse as kayaks, vehicle door and dash panels, refrigerator liners, utility vehicle beds, and plastic pallets.

The heated sheet slides into a form station where a mating mold and pressure-box close on the sheet, with vacuum then applied to remove trapped air and to pull the material into or onto the mold along with pressurized air to form the plastic to the detailed shape of the mold. After a short form cycle, a burst of reverse air pressure is actuated from the vacuum side of the mold as the form tooling opens, commonly referred to as air-eject, to break the vacuum and assist the formed parts off of, or out of, the mold. The sheet remaining after the formed parts are trimmed is fed into an inline granulator for recycling.

Accu-Form recycles their scrap and waste plastic, either by compressing in a baling machine or by feeding into a granulator (grinder) and producing ground flake, for sale to reprocessing companies or re-use in their own facility. Frequently, scrap and waste plastic from the thermoforming process is converted back into extruded sheet for forming again.