Name: common wood flaws in lumber
Uploaded: 2024-09-12T16:16:32.000Z
Duration: 1 min 23 s
Channel: JoVE

I difetti di crescita nel legno includono nodi, che si formano dove i rami si collegano al tronco dell'albero, nodi che derivano da nodi allentati che cadono, decomposizione e danni da insetti.
Le scosse sono fratture minori che corrono lungo o attraverso gli anelli annuali e sono difetti comuni del legno.
Wane si riferisce alla mancanza di legno o alla presenza di corteccia lungo il bordo di una tavola.
I controlli sono le crepe radiali che si sviluppano nei tronchi e sono difetti di fabbricazione che si verificano a causa del ritiro circonferenziale che porta alla contrazione durante il processo di stagionatura.
L'ordito si riferisce a qualsiasi deviazione da una superficie piana e precisa nella tavola. I tipi di ordito includono la curvatura, l'incurvamento, la torsione e la coppettazione nel legname.
L'alveolatura si riferisce a crepe interne in una tavola che si verificano a causa di una stagionatura impropria.
Le venature strappate derivano dal legno scheggiato o scavato dalla superficie della tavola a causa del taglio o della piallatura. Questi difetti influiscono sulla resistenza del legno.
Potrebbero apparire macchie superficiali sul legno dopo che è stato trasformato in legname. Queste macchie marroni, verdi o blu di solito influenzano l'aspetto ma non la resistenza del legname.

difetti del legname

Lumber Defects

I difetti del legname, che possono influenzare sia l'aspetto che l'integrità strutturale del legno, includono una varietà di difetti che avvengono in fase di crescita e di fabbricazione. Difetti di crescita come nodi e fori di nodi si verificano dove i rami erano un tempo attaccati al tronco dell'albero, con fori di nodi che si formano quando questi nodi cadono. Altri difetti naturali includono decadimento e danni da insetti, che compromettono la resistenza e la durata del legno.

Le scandole sono piccole fratture che corrono lungo o attraverso gli anelli annuali del legno, mentre il declino è caratterizzato dalla mancanza di legno o dalla presenza di corteccia lungo il bordo di una tavola, in genere derivanti dal modo in cui il legname viene tagliato. Le fessure sono crepe radiali all'interno del legno, che appaiono quando il legno si asciuga e si restringe circonferenzialmente durante il processo di stagionatura.

La deformazione è una deviazione dalla superficie piana del legno e può manifestarsi come curvatura, incurvatura, torsione o convessità, ciascuna delle quali influisce sull'usabilità del legname. L'alveolare si riferisce a crepe interne causate da una stagionatura impropria, che può indebolire il legno internamente.

La grana strappata è un altro difetto che si verifica durante il processo di taglio o piallatura, dove il legno si scheggia, dando origine a una superficie ruvida. Infine, dopo la lavorazione possono svilupparsi macchie superficiali come scolorimenti marroni, verdi o blu. Queste macchie in genere influenzano solo l'aspetto del legno e non la sua resistenza.

Comprendere questi difetti è fondamentale per gestire la qualità del legno e garantire che il legname soddisfi gli standard necessari per usi di costruzione e produzione.

I difetti di crescita nel legno includono nodi, che si formano dove i rami si collegano al tronco dell'albero, nodi che derivano dalla caduta di nodi allentati, decadimento ...

Education

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JoVE Core

Civil Engineering

Ingegneria Civile

Unit 1

Unità 1

Wood

Legno

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

common wood flaws in lumber

Lumber defects are flaws in wood that can change both its appearance and its strength. These defects come from tree growth and from the way lumber is processed. Knowing the main defects helps explain why some boards are better for construction and manufacturing than others.

Some defects begin in the tree itself. Knots form where branches were once attached to the trunk, and knotholes appear when those knots fall out. Decay and insect damage are also natural defects that can weaken wood and reduce its durability.

Other defects come from splitting, cutting, or drying the lumber. Shakes are small fractures that run along or across the annual rings. Wane is the missing wood or bark left along a board edge after cutting. Checks are radial cracks that form as wood dries and shrinks during seasoning, and honeycombing is a set of internal cracks caused by improper seasoning.

Warping changes the flat shape of a board. It can show up as crooking, bowing, twisting, or cupping, and each form can make the lumber harder to use. Torn grain is another processing defect, where the wood chips away during cutting or planing and leaves a rough surface. Surface stains, such as brown, green, or blue discoloration, may also appear after processing. These stains usually affect appearance more than strength.

Common Wood Flaws in Lumber

introduction to wood

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Wood is a construction material made from trees. A tree trunk has several layers. The outside is a protective layer of dead bark. Under that is living bark, then the cambium, then sapwood. As sapwood matures, it becomes heartwood. The pith sits at the center of the trunk. The age of a tree can be read from its growth rings. These rings are concentric bands seen in a trunk cross-section. Wood strength also depends on grain. Grain refers to elongated, tubular cells that run along the length of...

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lumber

Lumber Cutting Methods

Lumber is made from logs that are harvested, debarked, and processed into long pieces with a rectangular cross-section. The process starts when an automated saw slices a log into slabs. Those slabs then move on a conveyor belt to smaller saws, where they are cut into square-edged pieces of specific widths. Freshly cut lumber usually has rough surfaces. Its dimensions may also vary slightly from one end to the other. The way wood is cut affects both the lumber’s appearance and how it is used. <br...

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structural-properties-and-dimensions-of-lumber

Wood Strength Tests and Lumber Sizes

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wood surfacing

Wood Surfacing for Smooth, Safe Lumber

Wood surfacing smooths lumber, improves its size accuracy, and makes it safer to handle. It is a key finishing step in woodworking and construction. The process also helps correct small distortions that can form as wood dries. Before surfacing, the wood may be sized slightly larger to account for shrinkage during seasoning, which is the drying stage. A plane, a tool with rotating blades, is used to remove material and smooth the surface. The same tool can also round the edges a little, which...

lumber defects

Lumber defects are flaws in wood that can change both its appearance and its strength. These defects come from tree growth and from the way lumber is processed. Knowing the main defects helps explain why some boards are better for construction and manufacturing than others. Some defects begin in the tree itself. Knots form where branches were once attached to the trunk, and knotholes appear when those knots fall out. Decay and insect damage are also natural defects that can weaken wood and...

wood fasteners

Wood Fastener Types and Uses

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veneer

How Veneer Is Cut and Used

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key terms and concepts

Learn the main lumber defects found in wood, from knots and decay to warping, checks, and stains, and how they affect strength and appearance.

Common Wood Flaws in Lumber | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

Common Wood Flaws in Lumber

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