AQA A-level Design and Technology: Performance Characteristics of Woods

AQA A-level Design & Technology: Performance Characteristics of Woods

Introduction

This tutorial explores the performance characteristics of various woods commonly used in design and technology. We'll examine the stock forms, properties, and sustainability of softwoods, hardwoods, and manufactured boards. Understanding these characteristics is crucial for selecting the appropriate material for your design project.

Stock Forms of Timber

Timber comes in various stock forms, each suited to different applications:

• Sawn Timber: Cut from logs into rectangular sections, available in various lengths, widths, and thicknesses.
• Planks: Wide, flat pieces of timber with a thickness less than the width.
• Battens: Narrow, rectangular pieces of timber with a width less than the thickness.
• Scantlings: Timber with a square cross-section.
• Sleepers: Long, rectangular pieces of timber, often used in railway tracks.
• Beams: Large, strong pieces of timber used for structural support.

Softwoods: Properties & Applications

Softwoods are generally sourced from coniferous trees like pine, spruce, and fir. Their characteristics include:

• Grain Pattern: Straight and consistent, often with knots.
• Warping: Can be prone to warping due to moisture changes.
• Moisture Resistance: Less resistant to moisture than hardwoods.
• Joinery: Easy to work with, often used in butt joints and dado joints.
• Machining Qualities: Easy to machine due to soft nature.
• Applications: Construction framing, furniture, plywood, and paper.

Ecological Considerations:

• Fast-growing: Renewable resource, but some species are over-harvested.
• Sustainable Practices: Look for FSC-certified wood to ensure responsible sourcing.

Hardwoods: Properties & Applications

Hardwoods come from deciduous trees like oak, maple, and cherry. They are known for:

• Grain Pattern: Varied and intricate, often with figure and colour variation.
• Warping: Less prone to warping than softwoods.
• Moisture Resistance: More resistant to moisture than softwoods.
• Joinery: More challenging to work with, used in mortise and tenon joints.
• Machining Qualities: Can be more challenging to machine due to density.
• Applications: Fine furniture, flooring, musical instruments, and boat building.

Ecological Considerations:

• Slow-growing: Requires careful management to ensure sustainable harvesting.
• Endangered Species: Some hardwoods are endangered, making responsible sourcing crucial.

Manufactured Boards: Properties & Applications

Manufactured boards provide cost-effective and sustainable alternatives to solid wood. Some common types include:

• Plywood: Composed of thin veneers glued together in alternating directions for strength and stability.
• Chipboard: Made from wood chips bonded with resin, ideal for furniture and shelving.
• Medium Density Fibreboard (MDF): Made from wood fibres bonded with resin, offering a smooth, consistent surface.
• Oriented Strand Board (OSB): Constructed from wood strands glued together, often used in construction.

Performance Characteristics:

• Grain Pattern: Varies depending on the type of board.
• Warping: Less prone to warping than solid wood, but can still be affected by moisture.
• Moisture Resistance: Generally more resistant to moisture than solid wood, but not waterproof.
• Joinery: Can be difficult to join, requiring specialized techniques.
• Machining Qualities: Easy to machine, offering smooth surfaces and consistent results.

Ecological Considerations:

• Sustainable Resources: Often made from recycled wood or plantation timber.
• Formaldehyde Emissions: Some boards can emit formaldehyde, choose low-VOC options.

Sustainable Design Practices

• Use Recycled Timber: Consider reclaimed or salvaged wood for unique and sustainable designs.
• Choose FSC-Certified Wood: Support responsible forestry practices by using FSC-certified timber.
• Minimize Waste: Plan your projects carefully to minimize material waste and ensure efficient use of resources.

Conclusion

Understanding the performance characteristics of various woods is vital for successful design and technology projects. By selecting appropriate materials and employing sustainable practices, you can create innovative and responsible designs while respecting the environment. Remember to research and carefully consider the specific requirements of your project to choose the best option for your needs.