Glossary

There are a lot of industry tems to sort through in manufacturing. The custom molding glossary below is provided to help define the most common terms used in the industry.

Additive

A substance added in small amounts to alter or enhance properties.

Aging

The process of materials changing with time, affecting performance.

Annealing

Heating and slowly cooling to relieve stress and improve properties.

ANSI

The American National Standards Institute, a nonprofit organization.

Assembly

The process of fitting together parts to create a whole.

ASTM

The American Society for Testing and Materials, a standards organization.

Barrel

A cylindrical container used in various processes such as mixing, storing, or transporting materials.

Backing Plate

A rigid support or surface, often made of metal or other durable material, used to reinforce or attach components.

Bleed

The process of unwanted material, like air or liquid, escaping from a confined space or through a seal.

Blister

A raised area on a surface, typically caused by the trapping of fluid or air beneath it.

Blow Molding

A raised area on a surface, typically caused by the trapping of fluid or air beneath it.

Boss

A protruding feature, often with a threaded hole, used for attaching components or providing structural support.

Bubble

A small, spherical or elongated pocket of air or gas trapped within a solid or liquid material.

Blast Finishing

A surface treatment method that uses abrasive materials, such as sand or shot, propelled at high velocity to clean, smooth, or roughen a surface.

Blushing

A cosmetic defect in coatings, where a milky or hazy appearance forms due to moisture absorption or other factors.

Burned

A condition where a material is damaged or discolored by exposure to heat or flames.

Bridge Tool

A tool designed to form or manipulate materials, often used in manufacturing or construction.

Cavity

The void or space in a mold where the molten material is injected to create a specific shape.

Chamfer

A beveled edge or corner that's added to a part to prevent sharp edges or for assembly purposes.

Clamp Force

The force applied by the clamping unit of a molding machine to keep the mold closed during injection.

Core

The part of a mold that creates the interior features and holes of a molded part.

Cycle Time

The total time it takes to complete one molding cycle, including injection, cooling, and ejection.

Center Gated Mold

A mold design with the gate (entry point for molten material) at the center of the part.

Chromium Plating

A surface treatment method that involves depositing a layer of chromium onto a part for improved aesthetics and corrosion resistance.

Compression Molding

A molding process that involves compressing a preheated material in a mold cavity to form a part.

Cooling Channels

Passageways within a mold that circulate a cooling fluid to control the temperature during the molding process.

Cure

The process of setting or hardening a material through chemical reactions, often accomplished through heat or time.

Casting

A manufacturing process where a material, often metal, is heated until it becomes liquid and is then poured into a mold to create a part.

Clamp

The mechanism on an injection molding machine that holds the mold closed against the force of injection.

Co-Injection

A molding process that injects two or more materials into a mold simultaneously to create a part with multiple layers or properties.

Cold Flow Lines

Imperfections on the surface of a molded part due to material flow issues during injection molding.

Colorant

A substance added to the material to provide color to the final molded part.

Compound

A material made up of two or more different materials, usually a polymer mixed with additives or fillers.

Cooling Time

The period during which the molded part is allowed to cool and solidify within the mold

Delamination

The separation of layers or laminates within a material, which can lead to the weakening or failure of the part.

Density

The mass per unit volume of a material, typically measured in grams per cubic centimeter (g/cm³) or pounds per cubic inch (lb/in³).

DFM (Design for Manufacturability)

A set of guidelines and principles used to optimize the design of a product for efficient and cost-effective manufacturing processes. DFM aims to prevent design issues that could lead to production challenges or defects.

Diaphragm Gate

A type of gate design in injection molding where a thin diaphragm-like structure controls the flow of molten material into the mold cavity.

Draft Angle

A slight taper or angle applied to the vertical walls of a part to facilitate its ejection from the mold.

Durometer

A measurement of the hardness or stiffness of rubber or other flexible materials, often tested using a durometer gauge.

EDM (Electrical Discharge Machining)

A machining process that removes material from a workpiece using electrical discharges between an electrode and the workpiece. EDM is often used to create intricate shapes or fine details.

Ejection

The process of removing the molded part from the mold cavity, often assisted by ejector pins or other mechanisms.

Ejector Pins

Small cylindrical pins used in injection molding to push the molded part out of the mold cavity once it has solidified.

Elastomer

A type of polymer with elastic properties, often used in applications requiring flexibility and resilience.

Electroplating

A metal finishing process in which a thin layer of metal is deposited onto the surface of a part using an electrochemical reaction.

Elongation at Break

A measure of a material's ability to stretch or deform before breaking. It is typically expressed as a percentage of the original length. Elongation at break is a key property for materials like rubber and elastomers.

Embossing

A manufacturing process that creates raised or sunken designs, patterns, or letters on a surface, typically by pressing into the material.

Extrusion

A manufacturing process that produces parts with a consistent cross-section by forcing material through a die.

Family Mold

A single mold that creates multiple, related parts in a single molding cycle.

Fiber

Reinforcing material often used in composite materials like fiberglass.

Filler

A substance added to plastic materials to improve strength, reduce cost, or modify properties.

Finish

The surface quality or texture of a molded part.

Flash

Excess material that escapes from the mold cavity during the molding process.

Flow Line

A visible line or mark on a molded part where the material flow paths meet.

Flow Marks

Surface imperfections on a molded part caused by inconsistent material flow.

Gas-Assisted Molding

A molding process that uses gas pressure to hollow out thick sections of a part, reducing material use and improving structural integrity.

Gate

An entry point in the mold through which molten material enters the cavity.

Glass Fillers

Fine glass particles added to plastic materials to enhance their strength and stiffness.

Hardness

Resistance to deformation or indentation; measured using durometer scales (Shore A for rubber, Shore D for hard plastics).

Hot Runner Mold

Injection mold with a heated runner system to maintain plastic material in a molten state, reducing waste and enhancing molding efficiency. Common in plastic component production.

Injection

The process of injecting molten plastic or rubber material into a mold to create a component or part.

Injection Pressure

The force exerted to push molten material into a mold during the injection molding process, impacting the quality and characteristics of the molded part.

Insert Molding

A molding process that inserts pre-made components (inserts) into the mold and then overmolds them with plastic or rubber material to create a finished part.

Insulated Runner

A runner system in a mold designed to minimize heat transfer and energy loss during the injection molding process.

Jetting

A molding defect that occurs when molten material streams into the mold too quickly, causing a visual defect on the finished part.

Jig

A specialized tool or device used to hold and guide components during the assembly or manufacturing process, ensuring accuracy and consistency.

Knit Lines

Also known as weld lines, these are marks or lines on a molded part where two flow fronts of molten material meet and join during the molding process, often creating a cosmetic or structural imperfection.

Linear Mold Shrinkage

Linear mold shrinkage refers to the reduction in the size of a plastic part in the direction of flow during the cooling phase of injection molding.

Liquid Injection Molding

Liquid injection molding (LIM) is a process that involves injecting liquid silicone rubber into a mold to produce a wide range of elastomer products.

Matte Finish

A matte finish is a surface texture or appearance that is non-reflective, offering a soft, flat, and low-gloss look. It is often applied to plastic or rubber parts for aesthetic or functional purposes.

Mechanical Property

Mechanical properties refer to the physical characteristics of materials, such as hardness, toughness, and strength, that determine how they respond to mechanical forces or loads.

Mold

A mold, in manufacturing and plastic/rubber molding, is a hollow container used to give shape to liquid or softened materials that harden as they cool.

Multi-Cavity Mold

A multi-cavity mold is a mold design with multiple cavities, allowing for the simultaneous production of several identical parts in a single molding cycle.

Multi-Shot Molding

Multi-shot molding is an injection molding process that allows different materials or colors to be injected into different sections of a single part during a single molding cycle.

Nozzle

In injection molding, a nozzle connects the machine to the mold, allowing molten material to flow into the cavity. It ensures temperature control for proper material flow and part quality.

Overmolding

A molding process where a single part is formed using two or more different materials. This involves molding additional materials over a base part to enhance its properties or functionality.

Parting Line

The line or surface on a molded part where two halves of the mold meet. It's a visible seam or mark created during the molding process.

Pellets

Small, granular pieces of plastic material used as the raw material in the injection molding process.

Pinpoint Gate

A type of gate in injection molding that creates a small, focused entry point for molten plastic to enter the mold cavity, reducing visible marks on the final part.

Plastic

A synthetic material made from various polymers and additives, widely used in molding processes due to its versatility.

Plastic Deformation

The process by which a material undergoes a permanent change in shape when subjected to stress.

Plasticity

The property of a material that allows it to be easily molded or shaped without breaking or cracking.

Plasticizer

An additive incorporated into plastic formulations to increase their flexibility, workability, and durability.

Polymer

A large molecule composed of repeating structural units, or monomers, often used as the base material in plastic molding.

Press

A machine used in molding to apply pressure for compacting materials into the mold cavity.

Prototype Mold

A temporary mold used for creating prototype parts before the final production mold is made.

Ram

The part of a molding machine that applies force to the mold's clamping unit, allowing the mold to close and keep it securely shut during the injection process.

Reinforcement

Adding materials like fibers or fillers to plastics to enhance their strength, rigidity, and other mechanical properties.

Residence Time

The total duration that plastic material spends in the heated barrel of the molding machine, which can affect the material's properties and quality.

Resin

The base material used in plastic molding, often a type of polymer or plastic compound.

Rib

A thin, elongated projection added to a molded part to provide extra strength or support.

Rockwell Hardness

A measure of a material's hardness based on its ability to resist permanent indentation under an applied load.

Runner System

A network of channels or passages in a mold used for transporting molten plastic from the injection unit to the mold cavities.

Single-Cavity Mold

A mold with only one cavity, which produces one part per molding cycle.

Sink Mark

A surface depression or indentation on a molded part caused by the shrinking of the material as it cools.

Shear

The force or deformation that occurs when layers of plastic move parallel to each other in a molding process, which can affect the material's properties and final appearance.

Short Shot

A molding defect where the mold is not completely filled, resulting in an incomplete or "short" molded part.

Shot

The amount of molten plastic injected into the mold during each cycle of the molding process.

Shrinkage

The reduction in the size or volume of a molded part as it cools and solidifies, often expressed as a percentage.

Slide

A component in a mold that moves perpendicularly to the mold's opening and closing direction, used for creating undercuts or complex features in molded parts.

Stabilizer

An additive used in plastics to prevent or reduce degradation due to heat, UV light, or other environmental factors.

Stack Mold

A multi-level mold that allows for multiple moldings to be produced in each cycle, significantly increasing productivity.

Sprue

The main channel in the runner system that connects the nozzle of the injection unit to the mold cavity, allowing the flow of molten plastic.

Tapping

The process of creating threads inside a hole or mold to allow screws, bolts, or other threaded components to be fastened securely.

Tensile Strength

The maximum amount of tensile (pulling) stress a material can withstand without breaking, often measured in units of force per unit area.

Thermal Conductivity

A measure of a material's ability to conduct heat, which is important in molding for controlling the temperature of the material and the mold.

Thermoforming

A manufacturing process where plastic sheets are heated and formed into a specific shape using a mold.

Thermoplastic

A type of polymer that becomes soft and malleable when heated and solidifies when cooled. This process can be repeated without significant degradation.

Thermoplastic Elastomers

A type of thermoplastic polymer that combines the characteristics of rubber with those of plastic. They can be repeatedly heated and reshaped.

Thermoset

A type of polymer that, when heated, undergoes a chemical reaction that causes it to set into a specific shape, and it cannot be remelted or reshaped.

Tolerance

The allowable range of variation from a specified dimension or property in a molded part. Tolerances ensure that parts meet design requirements.

Tonnage

In injection molding, it represents the clamping force that a machine can exert to keep the mold closed during the injection process.

Tool

In the context of molding, this refers to the mold itself, which is the tool used to shape plastic or rubber into the desired form.

Transfer Molding

A molding process where the material is preheated and then forced into a heated mold cavity to cure and solidify.

Undercut

A feature in a molded part with a recess or protrusion that prevents the part from being easily removed from the mold. Special mold designs or additional mold actions are required to accommodate undercuts.

Underflow

A molding defect where the material doesn't completely fill the mold, leaving unfilled or thin areas in the final part. This can occur due to various factors like insufficient pressure, temperature, or flow rate.

Vacuum Forming

A plastic molding process that uses vacuum pressure to shape heated plastic sheets over a mold.

Vent

Small channels or openings in a mold designed to allow air to escape during the molding process.

Vestige

Unwanted excess material or residue on a molded part.

Warpage

Deformation or twisting in a molded part due to cooling and contraction of the material.

Water Absorption

The ability of a plastic material to absorb moisture from the surrounding environment, which can affect its mechanical properties.

Weld Line

A visible line or seam where two flow fronts of molten plastic meet during the molding process.

Welding

The process of joining two separate pieces of plastic by heating and melting the contacting surfaces to create a permanent bond.

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