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G code
Alternative form of G-code; CNC machine instructions that govern movements, speeds, tool changes and related commands.
Rapid Prototyping Glossary
G
Definitions for commercial rapid prototyping, production, machining, casting, moulding, finishing and inspection terms.
G-code
The machine code commonly used to command CNC machines and many 3D printers.
Galling
Severe adhesive wear that causes material transfer between sliding metallic surfaces.
Gang tooling
A tooling arrangement that holds multiple tools in sequence for turning or drilling operations.
Garnet
The abrasive mineral most commonly used in waterjet cutting to help erode material efficiently.
Gas-assisted injection moulding
An injection-moulding variant in which inert gas such as nitrogen is injected after the melt to hollow thicker sections, reduce sink marks and lighten the part.
Gate
The opening through which molten material enters a mould cavity.
Gate freeze
The condition in which the gate solidifies and no further material can be packed into the cavity; also called gate freeze-off. It is used to establish effective hold time.
Gate seal
The process condition at which the gate has frozen sufficiently that additional hold pressure no longer changes part mass. Gate seal studies are used to optimise hold time and avoid over-processing.
Gate vestige
The small scar or witness left on a part where the gate was removed.
Gating system
The sprue, runners and gates used to deliver material into a mould or casting cavity.
Gauge R&R
Gauge repeatability and reproducibility; a study used to assess measurement system variation.
GD&T
Geometric dimensioning and tolerancing; a symbolic system for controlling allowable geometric variation.
Geometric dimensioning and tolerancing
GD&T; the drawing language that communicates form, orientation, position, runout and related tolerance requirements.
Glass bead blasting
A blasting process using fine glass beads to clean and texture parts without heavy stock removal.
Glass transition temperature
Tg; the temperature range at which an amorphous polymer changes from glassy to rubbery behaviour.
Glass-filled nylon
A nylon grade reinforced with glass fibre to increase stiffness, heat resistance and dimensional stability.
Glass-reinforced polyester
GRP; a polyester matrix composite reinforced with glass fibres and used in tooling, housings and other lightweight structural applications.
Gloss level
The degree of surface reflectivity specified for a painted, moulded or coated finish.
Go/no-go gauge
A simple gauge that quickly verifies whether a feature falls within defined limits.
Gold plating
The application of a thin gold coating for conductivity, corrosion resistance, solderability, wear characteristics or decorative appearance.
Gouging
Unintended removal of extra material caused by an incorrect toolpath, set-up error or collision.
Granulate
Small polymer pellets or regrind particles used as moulding feedstock.
Gravity die casting
A reusable-die casting process in which molten metal fills the die under gravity rather than under high injected pressure.
Green machining
Machining a part before final sintering or heat treatment, when the material is softer and easier to cut.
Green part
An unsintered or partially cured part that still requires later thermal processing.
Grinding
A machining process using an abrasive wheel to achieve fine finish, close tolerance or both.
Grit blasting
A more aggressive blasting process than bead blasting, commonly used for cleaning or preparing a surface for coating.
GRP
Abbreviation for glass-reinforced polyester.
Gusset
A reinforcing rib or web used to stiffen a part or structure.