Thermoforming Glossary

Blister– Pre-formed custom plastic packaging used for consumer goods. The “formed” cavity or pocket contains the product and the “lidding” seals the product in the package.

Blow forming– A manufacturing process by which hollow plastic parts are formed. It is a process used to produce hollow objects from thermoplastic.

CAD (Computer-aided Design)– The use of computer technology for the design of objects, real or virtual.

CAM (Computer-aided Manufacturing)– The use of computer software to control machine tools and related machinery in the manufacturing of workpieces.

Clamshells– Clear plastic packaging that showcases an array of products from retail, food, medical, etc. The word clamshell indicates that the formed plastic package has one or more hinges.

Cutting Nest- A formed nest for formed product to sit in while being cut. Ensures a clean and accurate cut

Die Cutting– The process of using a die to shear webs of low strength materials, such as plastics. Die cutting can be done on either flatbed or rotary presses. Rotary die cutting is often done inline with printing.

Distortion Printing– Unique process where artwork is modified to anticipate distortion produced by thermoforming. Once the distortions are predetermined, calculated and implemented into the art, the printing process begins, followed by the thermoforming process.

Draw Ratio- The ratio of the (drawn) area of the formed part and that of the unformed sheet of material required to form the part.

Embossing– Process for producing raised or sunken designs, or relief in custom plastic packaging. Aesthetic and functional.

Hot Stamping– Dry printing method in which a heated die and foil are used to apply graphics to a surface.

Inline forming– Process where a plastic sheet moves from a roll onto inline thermo formers and through the heating section. The heated thermoforming material advances into the forming section where pressure and/or vacuum force the plastic onto a mold. It then proceeds to another station where formed parts are finish-trimmed.

Mechanical forming– Uses matching positive and negative molds that are brought together against the heated plastic sheet, forcing it to assume the shape of the custom plastic packaging. In the pure mechanical forming method, air pressure (positive or negative) is not used at all.

Mold– Gives thermoplastic its shape during the thermoforming process.

Negative Mold– A mold with a concave cavity.

Plug Assist A form created to help push material down for it to be vacuum formed. If this isn’t used, webbing can occur which are small creases in the material on corners and edges. Bottoms of the cavity can get very weak in strength.

Polyethylene– Is a thermoplastic polymer consisting of long chains of the monomer ethylene

Polylactic Acid (PLA)- Eco-friendly biodegradeable thermoplastic derived from renewable resources.

Polymer– A large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a wide variety of properties.

Polypropylene– A thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including thermoformed packaging, stationery, plastic parts and reusable containers of various types, laboratory equipment, and automotive components.

Polystyrene– Is an aromatic polymer made from the aromatic monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. Polystyrene is one of the most widely used materials in custom thermoforming.

Positive Mold– A mold with a convex shape.

Pressure Forming– Version of thermoforming, whereby a sheet of plastic is heated to a forming temperature while pressure forces the plastic downward onto a mold or tool to form its shape.

Prototype– Original example of a product after it has been designed and thermoformed.

PVC (Polyvinyl Chloride)– A thermoplastic vinyl polymer constructed of repeating vinyl groups (ethenyls) having one of their hydrogens replaced with a chloride group. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene.

Rotary Forming– A thermoforming process consisting of multiple stations on a rotary table.

Skin Pack– A type of carded packaging where a product (or products) is placed on a piece of paperboard, and a thin sheet of transparent plastic is placed over the product and paperboard.

Solvent Bonding– Process in which the surfaces of parts to be joined are treated with a solvent.

Strike Plate- A kind of cutting board for thermoforming plastics. What the cutter strikes against.

Thermoforming– 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.

Thermoplastic– A polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently.

Ultrasonic Welding– An industrial technique whereby high-frequency ultrasonic acoustic vibrations are locally applied to work pieces being held together under pressure to create a solid-state weld. In ultrasonic welding, there are no connective bolts, nails, soldering materials, or adhesives necessary to bind the materials together.

Undercuts- Create larger nesting dimensions within the parts, the undercut design determines the stacking function of the final product. Undercuts also allow for reversed draft angles that provide a good snap fit between thermoformed products and their lids. Undercut features require precise detail, otherwise the snap will be weak and not serve its purpose.

Vacuum forming– A simplified version of thermoforming, whereby a sheet of plastic is heated to a forming temperature, stretched onto or into a single-surface mold, and held against the mold by applying vacuum between the mold surface and the sheet. The vacuum forming process can be used to make most custom plastic packaging, speaker casings and even car dashboards.