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L/D ratio
Length-to-diameter ratio, used to assess slender tools, extruder screws, nozzles and flow features.
Rapid Prototyping Glossary
L
Definitions for commercial rapid prototyping, production, machining, casting, moulding, finishing and inspection terms.
Laminate tooling
Tooling made from laminated materials such as board, sheet or stacked metals.
Laminated object manufacturing
LOM; a sheet-lamination additive process that bonds and cuts layers of sheet material.
Laser ablation
Removing material by laser energy, often for marking, cleaning or precision micromachining.
Laser cutting
Separating material with a focused laser beam, widely used for sheet metal, plastics and gaskets.
Laser engraving
Producing recessed text, logos or patterns with a laser.
Laser marking
Using a laser to create visible identification marks without necessarily cutting deeply into the surface.
Laser powder bed fusion
LPBF; a family of additive processes that use a laser to fuse powder in thin layers.
Laser scanning
Capturing geometry using a laser-based scanner for inspection or reverse engineering.
Laser sintering
A broad term often used commercially for powder-bed processes such as SLS or DMLS.
Laser spot size
The effective diameter of a laser beam at the working surface, influencing feature size and energy concentration.
Laser welding
Joining components using a focused laser heat source.
Lathe
A machine tool that rotates the workpiece against a cutting tool, used mainly for cylindrical parts.
Layer adhesion
The bond strength between adjacent layers in an additively manufactured part.
Layer height
The thickness of each deposited or cured layer in an additive process.
Layer lines
The visible stepped strata left by additive layer building.
Lead time
The elapsed time from order or release to delivery of finished parts.
Lead-in
The entry move by which a cutter approaches and blends into the main cutting path.
Lead-out
The exit move by which a cutter leaves the main toolpath in a controlled manner.
Leader pin
A hardened alignment pin that ensures accurate registration between mould halves during closing; also called a guide pin. It protects shut-offs and helps maintain parting-line accuracy.
Leak test
A test used to check whether a part or assembly seals properly under fluid or air pressure.
Lifter
A mould component that moves during ejection to release an undercut feature.
Light sanding
A mild abrasive finishing step used to remove minor high spots, support marks or coating defects.
Lights-out machining
Unattended CNC machining carried out with little or no operator presence, often overnight.
Linear grain finish
A directional brushed or sanded finish that leaves parallel grain lines on sheet metal or machined surfaces.
Linear tolerance
A permissible dimensional variation on a length, width, diameter or thickness.
Liquid silicone rubber
LSR; a two-part silicone system processed by injection moulding for flexible, heat-resistant parts.
Live tooling
Driven tools on a turning centre that rotate independently for milling, drilling or tapping while the part remains on the lathe.
Living hinge
A thin flexible section of plastic designed to bend repeatedly without separate hardware.
LKM mould base
A standardised mould base system used in toolmaking.
LOM
Abbreviation for laminated object manufacturing.
Lost-foam casting
A casting process in which a foam pattern is surrounded by sand and vaporised by the incoming molten metal.
Lost-PLA casting
An investment-casting route that uses a 3D-printed PLA pattern which is later burnt out.
Lost-wax casting
Traditional alternative name for investment casting, referring to the wax pattern that is removed before pouring.
Low-ash polymer
A pattern material formulated to burn out with minimal ash, helping to reduce residue and defects in investment-casting shells.
Low-pressure casting
A casting process that fills the mould under relatively low pressure, often to improve fill control and reduce turbulence.
Low-pressure moulding
A moulding method that encapsulates or forms parts at relatively low injection pressure, often to protect electronics.
Low-volume production
Production quantities that are too high for one-off prototyping but below mass-production scale.
LPBF
Abbreviation for laser powder bed fusion.
LSR
Abbreviation for liquid silicone rubber.