chapter 16 processes used to form woodmaterials. objectives two basic wood forming processes:...

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Chapter 16 Processes Used to Form WoodMaterials

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Page 1: Chapter 16 Processes Used to Form WoodMaterials. Objectives Two basic wood forming processes: bonding and bending. Composition boards: hardboard, insulation

Chapter 16

Processes Used to Form WoodMaterials

Page 2: Chapter 16 Processes Used to Form WoodMaterials. Objectives Two basic wood forming processes: bonding and bending. Composition boards: hardboard, insulation

Objectives

• Two basic wood forming processes: bonding and bending.

• Composition boards: hardboard, insulation board, and particleboard.

• Particleboards: wood pieces and resin binder.• Engineered wood material: reconstituted

wood.• Plasticizing wood: steam or soaking.

Page 3: Chapter 16 Processes Used to Form WoodMaterials. Objectives Two basic wood forming processes: bonding and bending. Composition boards: hardboard, insulation

Bonding Processes• Bonding processes use heat and pressure to compact particles into sheet stock in

the production of wood composite board.• Composition boards: 3 major types – hardboard, insulation board, and

particleboard.• Hardboard: has high tensile strength, high density, and low water absorption.• Insulation board: manufactured using pulp wood and bagasse (sugarcane). Water

and chemicals are added to turn the fibers into a continuous mat. The mats are fed into a drier , then cut and trimmed to size in sheets.

• Particleboard: is a panel material composed of small discrete pieces of wood bonded together in the presence of heat and pressure by an external binder. About 40% of the particleboard used today is purchased by the construction industry for flooring underlayment. Most of the remaining 60% is used as core material by the furniture industry.

Page 4: Chapter 16 Processes Used to Form WoodMaterials. Objectives Two basic wood forming processes: bonding and bending. Composition boards: hardboard, insulation

Lamination Process

• Lamination is used extensively for the construction of plywood.

• It involves sandwiching sheets of wood together to form larger pieces.

• Veneer is thin sheets cut from expensive wood.• These sheets are used as the exposed layer that is

glued over a core of less expensive wood.

Page 5: Chapter 16 Processes Used to Form WoodMaterials. Objectives Two basic wood forming processes: bonding and bending. Composition boards: hardboard, insulation

Plywood

• Plywood is made by gluing a number of layers together at right angles to each other.

• ANSI (American National Standards Institute) standards specify the species, strength, type of adhesive, and appearance of plywood.

• Lamination produces much stronger product than solid stock.• Bending: Steaming or soaking is a better way to bend wood.

The stock is subjected to steam or soaked in boiling water till the moisture content reaches 20%. It is then placed in a forming jig that conforms to the desired shape. It is kept in that position till it cools and dries.

Page 6: Chapter 16 Processes Used to Form WoodMaterials. Objectives Two basic wood forming processes: bonding and bending. Composition boards: hardboard, insulation

Summary• Bonding processes use heat and pressure to compact particles into sheet

stock in the production of wood composite board.• Composition boards: 3 major types – hardboard, insulation board, and

particleboard.• About 40% of the particleboard used today is purchased by the

construction industry for flooring underlayment. Most of the remaining 60% is used as core material by the furniture industry.

• Veneer is thin sheets cut from expensive wood.• These sheets are used as the exposed layer that is glued over a core of

less expensive wood.• Lamination produces much stronger product than solid stock.• Bending: Steaming or soaking is a better way to bend wood.

Page 7: Chapter 16 Processes Used to Form WoodMaterials. Objectives Two basic wood forming processes: bonding and bending. Composition boards: hardboard, insulation

Home Work

• 1. What are the 3 major types of composition boards?

• 2. What is veneer and where is it used?• 3. What is the advantage of lamination?