Glossary of Injection Moulding Terms And Phrases - Injection Moulders

Comprehensive Glossary of Injection Moulding Terms for UK Manufacturing

This glossary offers a detailed overview of the most common phrases and terms used in injection moulding, helping to demystify the process and enhance understanding within UK manufacturing. Whether you’re new to the field or a seasoned professional, this glossary will serve as a useful reference point for navigating the injection moulding process.

Abrasion Resistance: The ability of a material to withstand mechanical actions such as rubbing, scraping, or erosion, that progressively remove material from its surface.
Additive: A substance added to the base polymer to enhance certain properties. Examples include flame retardants, UV stabilisers, plasticisers, and colourants.
Annealing: A process of slowly cooling a moulded part to relieve internal stresses.
Antistatic: Additives used in the polymer to reduce or eliminate static electricity generation.
Assembly: The process of joining two or more moulded parts together to form a finished product.
Back Pressure: The pressure that resists the flow of plastic in the barrel of the injection moulding machine, usually caused by friction and viscosity of the molten plastic.
Barrel: The part of the injection moulding machine where the plastic is melted. It contains the screw which pushes the molten plastic through the machine.
Blow Moulding: A moulding process where heated plastic is blown into a mould to form a part.
Boss: A raised feature on a plastic part, often designed for fastening or alignment.
Cavity: The hollow part in the mould where the plastic is injected and cooled to form the desired part.
Clamping Force: The force applied to the mould to keep it closed during the injection of the molten plastic.
Colourant: A substance added to the raw plastic material to give it colour.
Copolymer: A polymer formed from two or more different monomers.
Core: The part of the mould that forms the internal surfaces of a moulded part.
Coring Out: The process of removing sections from the part design to save on material, reduce cooling time and weight.
Curing: A chemical reaction where a plastic hardens. This process is used with thermosetting resins.
Cycle: The complete sequence of operations in a process from start to finish, including filling, packing, cooling, and ejection of a moulded part.
Decompression: The act of slightly retracting the screw at the end of the plasticising cycle to relieve pressure before injection.
Degassing: The release or removal of gas from a plastic material in the barrel of the moulding machine.
Degradation: A deleterious change in the chemical structure, physical properties or appearance of a plastic.
Dew Point: The temperature at which air or a gas begins to condense.
Die: A metal block used in forming materials by casting, pressing, or extruding.
Draft: The degree of taper on a vertical surface of a moulded part, used to aid removal from the mould.
Drying: The process of removing moisture from materials before moulding.
Ejector Pins: Rods in a mould that push the part out after it has cooled
Family Mould: A mould where each cavity forms a different part of the final assembled product.
Feed Hopper: The area of an injection moulding machine where the raw plastic material is loaded and then conveyed into the barrel.
Feed Throat: The entry point of the material into the barrel of the injection moulding machine.
Filler: A relatively inert substance added to a plastic to improve properties, reduce cost, or control shrinkage.
Fill Point: The location in the mould where material is first injected.
Flashing: Excess material that seeps from the mould cavity during injection. It forms a thin lip or protrusion at the parting line.
Flow Marks: A wavy pattern or lines appearing on the surface of a moulded component, representing the flow of the polymer melt.
Flow Rate: The volume of material that flows through a given orifice within a given period of time.
Gate: The narrow opening through which the molten plastic is injected into the mould.
Hardness: The resistance of a material to compression and indentation.
Heating Zone: A section of the barrel in an injection moulding machine where the heat for melting the plastic is applied.
Hot Runner: A system of heating elements that allows the plastic to remain molten in the runner, reducing material waste.
Hydraulic Machine: A type of injection moulding machine that uses hydraulic pressure to inject the material into the mould.
Impact Strength: The ability of a material to withstand a suddenly applied load and to resist the rupture that such a load imposes.
Injection Blow Moulding: A two-step process of injection moulding the plastic into a ‘preform’ and then using these preforms, a second process of blow moulding to give the final shape.
Injection Point: The point where the plastic enters the mould.
Injection Speed: The speed at which the screw moves forward to push the molten plastic into the mould.
Injection Unit: The section of an injection moulding machine that heats and pushes the plastic into the mould.
Insert: A part that is placed in the mould prior to injection, around which the plastic material is moulded, forming an integral part of the final product.
Jetting: A defect that occurs when molten plastic shoots into the mould at a high velocity and solidifies before spreading out, resulting in a snake-like line.
Jigs: A type of custom-made tool used to control the location or motion of another tool.
Knit Lines: Also known as weld lines, these are lines that appear on a finished part where two flow fronts of molten plastic meet and solidify.
Knockout: The mechanism used to eject a part from a mould.
Living Hinge: A thin section of plastic that connects two segments of a part, allowing them to rotate relative to each other.
Low Volume Manufacturing: Production of a small quantity of parts, typically for testing, prototypes or small scale applications.
Masterbatch: A concentrated mixture of pigments or additives in a polymer carrier, used to colour raw polymer or impart other properties.
Melt Temperature: The temperature at which a polymer becomes fluid enough to inject into a mould.
Mould or Mould Cavity: The tooling used to create plastic parts in moulding.
Mould Release: A substance used to prevent the finished part from sticking to the mould.
Moulding Cycle: The sequence of events during the injection moulding of a plastic part.
Multi-Cavity Mould: A mould that has more than one mould cavity, used to manufacture multiple parts per cycle.
Non-Return Valve: A part of the injection unit that ensures the molten plastic does not flow back along the screw during injection.
Nozzle: The hollow component at the end of the heating barrel of an injection moulding machine. It directs the flow of material from the barrel into the mould.
Orientation: The alignment of the polymer chains in relation to the flow of the material.
Overmoulding: The process of injection moulding over a previously moulded part to form a single part. It’s used for adding soft touch surfaces, functional or decorative features.
Overflow Well: An extra cavity in the mould, generally outside the part area, designed to accept additional melt material.
Parting Line: The line on a moulded part where the two halves of the mould meet. This often leaves a minor imperfection in the surface of the part.
Polymer: A large molecule made up of repeating subunits, which can be natural like rubber, or synthetic like plastics.
Post-cure: An additional curing step, either at room or elevated temperature, to complete the cure of a moulded part.
Pot Life: The amount of time a catalysed thermosetting resin can remain workable before it starts to cure or set.
Pressure Drop: The decrease in pressure from one point in the system to another, caused by resistance to flow.
Processing Temperature: The temperature at which a plastic material is formed into a desired shape.
Purge: The process of cleaning an injection moulding machine of one colour or type of material by forcing another material through it.
PVC (Polyvinyl Chloride): A common thermoplastic polymer used in a wide variety of applications, including pipes, clothing, and cable insulation.
Regrind: Plastic scrap that has been ground up for reuse.
Release Agent: A substance used to prevent the moulded part from sticking to the mould.
Resin: The raw polymer used to make plastic parts. It often refers to the base polymer to which additives and fillers have been added.
Runner: The channel cut into the mould that guides the molten plastic from the sprue to the gates of the individual cavities.
Screw: The rotating component within the barrel of an injection moulding machine, which conveys, melts, mixes, and forces the material into the mould.
Shot Capacity: The maximum volume of plastic that can be injected in one injection cycle.
Shrinkage: The reduction in size of a plastic part as it cools after moulding.
Shut-off Angle: An angle designed on the part to aid in the sealing of the parting line in the mould.
Sink Marks: Localised depression or indentation on the surface of the part, often caused by uneven cooling and shrinkage.
Sprue: The passage through which molten plastic is injected into a mould.
Thermoplastic: A type of plastic that can be melted, reshaped, and then solidified again. This process can be repeated multiple times.
Thermosetting Plastics: A type of plastic that irreversibly hardens after being moulded and heated. It cannot be melted and reshaped again.
Tie Bar: A large diameter rod that holds the two halves of an injection moulding machine together.
Tolerance: The allowable variation in the size and shape of a moulded part.
Tool: Another term for the mould used in the moulding process.
Transfer Moulding: A process where the plastic is loaded into a chamber before the mould is closed, and then forced into the mould cavities.
Undercut: A feature in a moulded part that prevents it from being ejected from the mould in a straight line.
Vent: A shallow channel or opening cut in the mould to allow air and other gases to escape as the plastic fills the mould cavity.
Virgin Material: Plastic material in its original state, which has not been subjected to processing or reuse.
Viscosity: A measure of a fluid’s resistance to flow. It influences the flow of melted plastic into a mould.
Void: An unfilled space within a moulded plastic part. Voids are usually caused by shrinkage and/or trapped air within the part.
Warp: A deformation in the shape of a moulded part caused by non-uniform cooling and shrinkage during the cooling phase.
Wear Resistance: The ability of a material or surface to resist damage caused by friction or abrasion.
Weld Line: The line where two flow fronts of molten plastic meet and solidify. Also known as a knit line.
Yield Strength: The amount of stress at which a plastic deforms and does not return to its original shape after the stress is removed.
Zoning: Dividing the barrel of the injection moulding machine into separate areas for more precise control over temperature and plastic flow.

Phrases related to Injection moulding and the above glossary

ABS Injection Moulding: The process of injection moulding using Acrylonitrile Butadiene Styrene, a common thermoplastic.
Additives in Injection Moulding: Substances added to the base polymer to improve specific properties.
Automated Injection Moulding: Refers to the use of robotics or automated systems in the injection moulding process.
Barrel Temperature Control: The management of the temperature within the injection moulding machine’s barrel.
Blow Moulding vs Injection Moulding: A comparison of these two common plastic manufacturing techniques.
CAD for Injection Moulding: The use of Computer-Aided Design in designing moulds and parts for injection moulding.
Clamping Force in Injection Moulding: The force used to hold the mould closed during the injection process.
Cost-effectiveness of Injection Moulding: Discussion of the cost benefits of using injection moulding.
Cycle Time in Injection Moulding: The total time required to complete one cycle of the injection moulding process.
Defects in Injection Moulding: A discussion of common problems and defects that can occur during injection moulding.
Durable Parts by Injection Moulding: Emphasises the durability and strength of parts produced by injection moulding.
Efficiency of Injection Moulding: Discusses the efficiency and speed of the injection moulding process.
Flash in Injection Moulding: A term referring to the excess material that seeps out from the mould cavity during the injection process.
Flexible Parts by Injection Moulding: Discusses how injection moulding can create parts with a degree of flexibility.
Flow Rate in Injection Moulding: The volume of molten plastic material that flows in a given time during the injection moulding process.
Gate Location in Injection Moulding: The placement of the entry point for the molten plastic into the mould.
High-Volume Production Injection Moulding: Refers to injection moulding for large-scale, high-volume production.
Hydraulic vs Electric Injection Moulding Machines: A comparison of these two types of injection moulding machines.
Impact Strength in Injection Moulded Parts: Discusses the resilience and durability of injection moulded parts against impact.
Injection Moulding for Electronics: The use of injection moulding for creating components used in electronics.
Injection Moulding Machine Maintenance: Discusses the upkeep and routine checks required to keep an injection moulding machine in optimal condition.
Injection Moulding Polymers: The different types of polymers used in injection moulding.
Injection Pressure in Moulding Process: The pressure applied to inject the molten plastic into the mould.
Jetting in Injection Moulding: A defect that occurs when molten plastic shoots into the mould at a high velocity.
Knit Lines in Injection Moulding: Discusses the phenomenon of knit lines, which occur where two flow fronts of molten plastic meet and solidify.
Low-Volume Injection Moulding: Refers to injection moulding processes geared towards producing smaller quantities of parts.
Masterbatch in Injection Moulding: Discusses the role of masterbatches, which are mixtures of additives used to colour and modify the properties of raw polymer.
Material Selection for Injection Moulding: Discusses factors to consider when choosing the type of plastic material for an injection moulding project.
Multi-Cavity Moulds: Refers to moulds that have more than one cavity, allowing for the production of multiple parts per injection cycle.
Overmoulding Techniques: Discusses techniques for injection moulding one type of plastic over another, often used to add soft-touch surfaces or functional features.
Part Design for Injection Moulding: Talks about considerations and best practices when designing parts to be produced by injection moulding.
Plasticisers in Injection Moulding: Discusses the role of plasticisers, which are additives that increase the plasticity or fluidity of the material.
Post-Cure Process: Discusses the additional curing process, either at room or elevated temperature, to complete the cure of a moulded part.
Precision Injection Moulding: Refers to high-precision injection moulding techniques for creating intricate and detailed parts.
Prototyping with Injection Moulding: Discusses the use of injection moulding for producing prototype parts in the product development phase.
Quality Control in Injection Moulding: The processes and measures to ensure quality in injection moulded parts.
Polymer Injection Moulding: Discusses the use of various polymers in the injection moulding process.
Post-Processing in Injection Moulding: Talks about the necessary steps after moulding, such as removing sprue and improving the surface finish.
Preventive Maintenance for Injection Moulding Machines: Details the routine checks and upkeep necessary for ensuring the longevity of an injection moulding machine.
Product Lifecycle in Injection Moulding: Discusses the role of injection moulding in various stages of a product’s lifecycle, including prototyping and mass production.
Quality Assurance in Injection Moulding: Discusses measures and standards put in place to ensure the quality of injection moulded parts.
Rapid Injection Moulding: Refers to techniques for speeding up the moulding process, often used in prototyping and low-volume production.
Recycling in Injection Moulding: Discusses the potential for reusing and recycling plastic materials in injection moulding.
Resin Selection for Injection Moulding: Discusses the considerations in choosing the right resin or raw polymer for a moulding project.
Robotic Automation in Injection Moulding: The use of robots and automated systems in the injection moulding process.
Shot Size in Injection Moulding: Refers to the maximum amount of plastic that the injection moulding machine can inject in one cycle.
Thermoplastic Injection Moulding: Discusses the use of thermoplastics, which can be repeatedly melted and solidified, in injection moulding.
Tooling for Injection Moulding: Talks about the moulds used in the injection moulding process, and considerations in their design and construction.
Undercut in Injection Moulding: Refers to the feature in a moulded part that hinders straight-line ejection from the mould.
Validation Process in Injection Moulding: Discusses procedures to check and confirm that the injection moulding process will produce good parts.
Venting in Injection Moulding: The use of vents in the mould to allow trapped air and gases to escape when the molten plastic fills the cavity.
Warpage in Injection Moulded Parts: Discusses the deformation that can occur in injection moulded parts due to non-uniform cooling and shrinkage.
X-Ray Inspection of Injection Moulded Parts: The use of X-ray techniques to inspect and validate the internal structure of injection moulded parts.
Yield Strength of Injection Moulded Plastics: Discusses the stress at which a plastic part deforms and does not return to its original shape.
Zero-Defect Production in Injection Moulding: Refers to strategies and best practices for minimizing defects in the injection moulding process.

This glossary provides a comprehensive overview of key terms in injection moulding, equipping you with the language to better understand the processes involved in UK manufacturing. For more information about injection moulding or related services, visit Injection Moulders.

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