Glossary of Terms



Term Definition
Aging The change of a material with time under defined environmental conditions, leading to improvement or deterioration of properties.
Barrel The part of the molding press where resin is melted.
Boss The round protrusions on plastic parts and molds, often designed for fasteners.
Bridge Tool A temporary low production tool mold. It is made for the purpose of making production parts until a high volume production mold is ready.
Bubbles Air pockets that have formed in the material of the component. Bubbles may vary in size.
Cavity Concave in mold, which usually forms the outer surface of the molded part; depending on number of such depressions, molds are designated as a single cavity or multi-cavity.
Core The pressure applied to the mold to keep it closed during a cycle, usually expressed in tons.
Cycle The complete sequence of operations in a process to complete one set of moldings. The cycle is taken at a point in the operation and ends when this point is again reached and moving platens of the clamp unit in the fully open position.
Draft The degree of taper of a mold-cavity sidewall or the angle of clearance designed to facilitate removal of parts from a mold. Generally all plastic components should be designed with draft where possible.
Durometer The hardness of a material as measured by the Shore Durometer.
EDM Electric Discharge Machining. Sometimes colloquially also referred to as spark machining, spark eroding, burning, die sinking or wire erosion, is a manufacturing process whereby a desired shape is obtained using electrical discharges. Material is removed from the workpiece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage.
Ejector Pins Pins that are pushed into a mold cavity from the rear as the mold opens to force the finished part out of the mold. Also called knockout pins.
Family Mold A multi-cavity mold where each of the cavities forms one of the component parts of an assembled finished part.
Flash Any excess material that is formed with and attached to the component along a seam or mold parting line.
Flow Line Marks visible on the finished items that indicate the direction of the flow of the melt into the mold.
Flow Marks Wavy surface appearances on a molded part caused by improper flow of the melt into the mold.
Gate An orifice through which the melt enters the mold cavity.
Gate Trim Remnant of plastic left over from cutting the component from the runner or sprue, usually to be cut flush with the edge of the component.
Hand Load For low production mold with undercut, steel fixture which create the undercut are manually removed from the mold during the part ejection process.
Heel Refers to the portion of an automatic custom injection mold that keeps the slide in the forward position when the molding machine is closed on the mold.
Hot-Runner Mold A mold in which the runners are insulated from the chilled cavities and are kept hot. Hot-runner molds make parts that have no scrap.
Insert Molding Insert molding is the process of molding plastic around preformed metal inserts. This process is compatible with both thermoplastic and thermoset materials.
Jetting Turbulent flow in the melt caused by an undersized gate or where a thin section rapidly becomes thicker.
Knit Lines Where melted material flows together to form a line or lines that may cause weakening or breaking of the component.
Living Hinge A thin flexible hinge made from the same material as the two rigid pieces it connects. It is typically thinned to allow the rigid pieces to bend along the line of the hinge to allow them to open and close. They require careful design and gate placement. A typical application would be the top and bottom of a box.
Mold Frame A series of steel plates which contain mold components, including cavities, cores, runner system, cooling system, ejection system, etc.
Mud Sets A case where the manufacturer owns a base mold that contains the bulk of the equipment necessary for full automation. The Mud Set allows customer to cut a smaller insert that slides into the base and offers a fully automated production environment to reduce mold costs.
Multi-Cavity Mold A mold having two or more impressions for forming finished items in one machine cycle.
Over Molding A process in which a mold cavity is first partially filled with one plastic and then a second shot is injected to encapsulate the first shot.
Packing The filling of the mold cavity or cavities as full as possible without causing undue stress on the molds or causing flash to appear on the finished parts.Over packing or under-packing results in less than optimum fill.
Parting Line On a finished part, this line shows where the two mold halves met when they were closed.
Purging The forcing one molding material out of the plasticator with another material prior to molding a new material. Special purging compounds are used.
Ribs A thin support features (usually triangle shape) on a part that are used for strengthening wall sections and bosses.
Runner The channel that connects the sprue with the gate for transferring the melt to the cavities.
Shear Refers to when plastic enters into the mold and the melt is maintained by friction produced by speed and pressure. Too much shear can cause the plastic material to burn, too little can cause the material to freeze off causing short shot.
Short Shot Failure to completely fill the mold or cavities of the mold. Edges may appear melted.
Shrink Rate The dimensional differences between a molded part and the actual mold dimensions.
Single-Cavity Mold A mold having only one cavity and producing only one finished part per cycle.
Sink Marks A shallow depression or dimple on the surface of a finished part created by shrinkage or low fill of the cavity.
Slide Area of the custom plastic injection molds that is used for creating undercuts. Required for automatic injection molds
Slide Action A sliding mechanism in the mold designed for the molding of parts with undercuts. The undercut-steel fixture is held in place during the injection process and then slides out of the way prior to ejection.
Sprue The feed opening provided in injection molding between the nozzle and cavity or runner system.
Steel (Metal) Safe Part design change will only require to remove metal from mold instead of “weld-add” metal on the mold.
Straight Pull No side actions.
Undercuts A protuberance or indentation that impedes withdrawal from a two-piece rigid mold.
Vent A shallow channel or opening cut in the cavity to allow air or gases to escape as the melt fills the cavity.
Vestige A mark created by trimming the injection molded part gate.
Wall Thickness The thickness of the cross section of the plastic part.
Warp Dimensional distortion in a molded object. Caused by internal stresses via un-even material flow, cooling, and compression
Weld-Line Where melted material flows together during molding to form a visible line or lines on a finished part that may cause weakening or breaking of the component.
Term Definition
2D/3D Drawings Engineered drawings to represent what the final product will look like - a design rendering of the finished product. Customers always need to sign off on the drawing prior to the tooling being created.
Blister Pre-formed custom plastic packaging used for consumer goods. A package type that contains a product between a preformed (usually transparent plastic) dome or “bubble” and a paperboard surface or “carrier.” These can be seal blisters, trapped or captive blisters, slide blisters, welded blisters, tray blisters or returnable tray blisters.
Blow Forming A manufacturing process by which hollow plastic parts are formed. It is a process used to produce hollow objects from thermoplastics
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 workplaces
Cavity The parts of the thermoformed mold that combine to provide the container body shape
Chipboard The cardboard like material used to add stiffness and durability to a package. Thickness can vary depending on the design and the users need.
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
Cycle The complete, repeating sequence of operations in a process or part of a process. In thermoforming, the cycle time is the period, or elapsed time, between a certain point in one cycle and the same point in the next
C-Tray An album with the spine side of the product open to allow materials to be placed on the spine. A ring may be placed on the spine or pages could be sealed on the spine. There can also be trays holding other materials in either or both covers with room for literature in between on a spine mounted ring or sealed in pages.
Deburring Covers the range of finishing techniques used to remove the trim burrs (excess, unwanted material) on a trimmed thermoformed part
Die Tools designed to cut, shape or form materials to a desired shape.
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
Digital Printing Plateless imaging printing that uses digital data from pre-press systems
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
Drawing The process of stretching a thermoplastic sheet to reduce its cross-sectional area
Embossing Process for producing raised or sunken designs, or relief in custom plastic packaging, Aesthetic and functional
Family Mold A multi-cavity mold where each section forms one of the component parts of the assembled finished object
Female In thermoforming, the indented, recessed part of a mold
Flange A protruding rim, edge, rib or collar used to strengthen, hold in place or attach an object
Gauge The thickness of the material(s) being used to create the package. For example, PVC 25 ga. Represents that the PVC thickness is 25 gauge. The large the gauge, the thicker the material.
Gloss The shine or luster of the surface of a material
Hanging Tabs Use for hanging on merchandise displays, piggyback tags for attaching promotional items to other merchandise and product identification tags. Styles include slot, Euro-style, round hold, hook, and sombrero
Header Card A fold over display card used to hang product from a display peg at retail: It often traps a thermoformed package or clear plastic bag that retains product.
Hot stamping Dry printing method in which a heated die and foil are used to apply graphics to surface
Inline forming Process where a plastic sheet moves from a roll onto inline thermoformers 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
Mounting Plate The part of a thermoforming machine to which a mold is attached
Negative Mold A mold with a concave cavity
Plastic Recycling Code The recycling code found on the bottom of containers consisting of a triangle formed by three arrows with a number in the center and distinguishing letters under the triangle. The number codes are: 1) PET, PETE = Polyethylene terephthalate, 2) HDPE = high density polyethylene, 3) PVC = polyvinyl chloride vinyl, 4) LDPE = low density polyethylene, 5) PP = polypropylene, 6) PS = polystyrene, and 7) Other
Platen The mounting plates of a forming station to which the entire mold assembly is bolted
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 the thermoplastic polymer consisting of long chains of the monomer ethylene
Polylactic Acid (Pla) Eco-friendly biodegradable 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.
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
Prototype Mold A simplified mold made for the purpose of evaluation and testing prior to production. Prototype molds are often made from a light metal casting allo0y or from an epoxy resin
PVC Polyvinyl Chloride - A thermoplastic vinyl polymer constructed of repeating vinyl groups (ethynyls) having one of their hydrogens replaced with a chloride group. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene.
Rivet A small piece of metal used to hold the ring metal into a product. Depending on the package, rivets can be concealed, rivetless or exposed
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.
Thermoplastic A polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently
Tooling Cutting tools, dies, fixtures, gauges, jigs, molds, printing plates and specialized patterns that are generally specific to a product line or design
Tray A receptacle without a lid
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 help 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
Vinyl Scrim Vinyl scrim is reinforcement for a product. It is a loose fabric mesh that is in a sheet of vinyl that will not crack apart. Scrim is sealed in the spine of an album with spine bars and if a crack forms at the top or bottom of the spine hinge, the srim will p;revent the crack from continuing down the spine. This will keep the album from cracking apart at the hinges.
Web During forming, a fold of plastic that cannot be stretched flat against a mold surface