Wood Characteristics

Wood(sawn timber, plywood and particleboard)

Some Basic Characteristics of Wood:

It is highly versatile.

It is relatively light in weight

It is has good strength in both tension and compression

It provides toughness, rigidity and insulating properties.

A figure showing the durability of timber

http://www.woodworkersuk.co.uk/timber-durability.htm

The manufacturing process of wood

The figure provides a typical layout of a general manufacturing process of wood

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Pine plantations native forests are where mature trees are harvested from. Smaller logs can be produced from trees harvested at a younger age.

Hardwoods are valued highly and

1. Sawmilling

Sawmilling includes a number of activities from the transportation of logs to timber drying and sorting and also the classification. This requires different types of energy. In developing countries, most processes are mechanised highly and requirements for energy are basically met with the generation of a few kilowatts. The rest of the process is powered by animal power or low-cost manpower.The main aim is mainly to save energy required

1.1 Log sorting and barking

Logs are sorted on arrival and stored according to their characteristics.

Transporting of logs and its handling depends on the capacity of the sawmill operation. Manual and animal power may be used here in small portable sawmill units

The figure shows a simplified process flow of

This is all done before the it is presented to the headrig for breakdown.

It is sawn with a circular saw or bandsaw. A log carriage moves the log through the headsaw to achieve the best sawing pattern.

This is followed by further breakdown of slabs.

It is then cut to standardized lengths and specifications.

1.3 Sorting and grading

The timber is then sorted according to width, length, species, quality, grade and thickness.

The ends may then be brushed or dipped in a chemical solution to protect the sawntimber against insects and fungi.

1.4 Drying

Sawntimber is either kiln - or – airdried

Air drying is when the sawntimber is stacked in a way that it is exposed to a good flow of air until the required moisture content is attained.

Kiln dryingis when the sawntimber is dried in a closed and controlled environment.

1.5 Regrading and surfacing

It is then inspected for any defects before stacking for storage.

2. Plywood production

The figure shows a simplified process flow of plywood