ALUMINUM GLOSSARY - L

Lacquer

A solution of natural or synthetic resin in an organic solvent with modifying agents, suitable for protective coatings. Lacquers may be clear or colored.

Lambda

The Greek letter, corresponding to the letter L, used as a symbol for the coefficient of heat conductivity, the relative rate at which heat is transmitted through a material.

Lamination

An internal crack or separation aligned parallel to the extrusion direction, usually caused by contaminants that feed into the metal flow during the forming process or by cracked billets.

Lap Joint

A joint formed with one member overlapping the other; the simplest type of nesting joint.

Lapping

A method of finishing metal to produce a very smooth, highly accurate surface.

Layout Sample

A prototype forging or a cast used to determine conformance to designed dimensions.

Lead-out (equipment context)

The initial adjustable and removable section of runout table which is usually stationary (non-activated).

Lead-out (process context)

The initial portion of an extruded profile.

Light Walls

Undersized wall dimensions often caused by shifting or caving of mandrel or housing section of hollow die.

Lineal Temperature

Temperature along the extruded profile's length.

Linearity

The extent to which a measuring instrument's response is proportional to the measured quantity.

Line, Flow

The line pattern which shows the direction of flow on the surface.

Line, Looper

Closely spaced symmetrical lines on the surface of metal which has undergone non-uniform deformation, usually in a drawing operation.

Liner

The slab of coating metal that is placed on the core alloy and is subsequently rolled down to clad sheet as composite.

Liquation

The bleeding of the low-melting constituents through the solidified ingot surface.

Location

A general concept for the typical values or central tendency of a distribution.

Lock

A condition in which the parting line of a forging is not all in one plane.

Log

The starting stock for extrusion billet. Extrusion log is usually produced in lengths from which shorter extrusion billets are cut.

Long Transverse Direction

For plate, sheet and forgings, the direction perpendicular to the longitudinal direction which is also at right angles to the thickness of the product. See also Longitudinal Direction .

Longitudinal Direction

The direction of major metal flow in a working operation.

Lot , Heat Treat

Material usually of the same mill form, alloy, temper, section and size traceable to one heat-treat furnace load (or extrusion charge or billet in the case of press heat-treated extrusions) or, if heat treated in a continuous furnace, charged consecutively during an 8-hour period.

Lot , Inspection

(1) For non-heat treated tempers, an identifiable quantity of material of the same mill form, alloy, temper, section and size submitted for inspection at one time. (2) For heat treated tempers, an identifiable quantity of material of the same mill form, alloy, temper, section and size traceable to a heat treat lot or lots and submitted for inspection at one time. (For sheet and plate, all material of the same thickness is considered to be of the same size.)

Lube, High

Lubricant limit exceeds the maximum agreed upon limit measured in weight per unit area.

Lube, Low

Failure of the lubricant to meet the agreed upon minimum limit measured in weight per unit area.

Lubricant

Any of a number of liquids or semi-solids such as oil, kerosene, grease, lard, fat, soap, tallow and wax used on metal to reduce friction and binding during extruding or forming operations.