Timber Based Materials

This section focuses on timber-based materials, a key group of materials used in design and technology. These notes explore timber-based materials:  selection, properties, ecological impact, and the processes involved in their production.

Selecting Materials

When selecting timber-based materials, designers must consider:

• Strength: Different types of wood have different strength properties. For example, hardwoods like oak and ash are strong and durable, suitable for furniture, while softwoods like pine are lighter and easier to work with, making them ideal for construction or packaging.
• Aesthetic qualities: The grain, colour, and finish of the timber are crucial for products where appearance is important, such as furniture or interior design.
• Sustainability: Timber is a renewable resource, but the method of harvesting and the type of wood are important. Sustainable sourcing (e.g., FSC-certified wood) is key to reducing the material's ecological footprint.

Forces and Stresses

Timber-based materials are subject to various forces and stresses:

• Tensile stress: When timber is stretched, it may crack or break. For example, when wood is used as a beam, it needs to be strong in tension to avoid snapping.
• Compressive stress: Timber can compress under heavy loads, especially in construction applications like beams or columns.
• Shear stress: Forces acting in opposite directions, which can cause timber to split along its grain.
• Bending stress: Common in furniture making or structural uses. The strength of timber in bending depends on its grain direction and moisture content.

Understanding these stresses helps in selecting the appropriate wood for the intended use.

Ecological and Social Footprint

The ecological footprint of timber depends on its sourcing:

• Deforestation: If timber is sourced unsustainably, it contributes to deforestation, which harms biodiversity. Sustainable forest management practices aim to mitigate this impact.
• Carbon footprint: Timber absorbs carbon dioxide during growth, making it a carbon-neutral material if sourced responsibly. However, transportation and processing may increase its carbon footprint.
• Social impact: The conditions in which timber is harvested also affect its social footprint. Ensuring fair labour practices and local benefits is important for sustainable timber production.

Using FSC-certified timber helps ensure the material has a lower ecological and social footprint.

Sources and Origins

Timber is sourced from different types of trees:

• Hardwoods: Derived from deciduous trees (e.g., oak, beech, mahogany). These woods are dense, durable, and often used for high-quality furniture, flooring, and cabinetry.
• Softwoods: Sourced from coniferous trees (e.g., pine, spruce, fir). They are lighter and easier to work with, making them suitable for construction, packaging, and furniture.
• Exotic woods: Some timber, like teak or rosewood, comes from tropical regions. These woods are often more expensive and used for premium products.
• Recycled timber: Timber from old buildings or furniture that is reused, reducing the demand for new timber and its environmental impact.

Understanding the origin helps designers make informed choices about sustainability and quality.

Use of Material Properties in Commercial Products

The properties of timber make it suitable for different commercial products:

• Hardwoods: Strong, durable, and aesthetically pleasing, ideal for furniture, flooring, and high-end products like musical instruments.
• Softwoods: Lighter, easier to cut, and generally cheaper, making them ideal for construction, outdoor furniture, and interior joinery.
• Plywood: Made from layers of veneer glued together, offering strength and stability for products like cabinets, shelving, and construction materials.
• MDF (Medium Density Fibreboard): A composite material made from wood fibres, used for flat-pack furniture and decorative panels due to its smooth surface and ease of machining.
• Chipboard: Made from wood chips and resin, typically used for lower-cost furniture and construction due to its lower strength compared to plywood or solid timber.

Timber-based materials are selected based on their properties, such as strength, durability, and finish, to suit the end product.

Stock Forms, Types, and UK Sizes

Timber is available in various stock forms and sizes:

• Rough sawn timber: Wood that has been cut to rough dimensions but not planed smooth. Often used in construction.
• Planed timber: Wood that has been smoothed and finished on all sides. Suitable for furniture or joinery work.
• Plywood: Available in sheets, commonly in sizes like 2400 x 1200 mm or 1220 x 2440 mm, and in varying thicknesses from 3 mm to 25 mm.
• MDF and Chipboard: Available in sheets, often 2440 x 1220 mm in size. These materials are often used in flat-pack furniture.
• Lumber (timber lengths): Available in standard lengths (e.g., 2.4 m, 3.6 m, 4.8 m) and widths depending on the project needs.

UK timber sizes often follow imperial measurements (e.g., 2x4, 6x2), although metric sizes are increasingly used in modern construction.

Scales of Production

The scale of production affects the type and form of timber used:

• One-off production: Custom or bespoke furniture often uses high-quality hardwoods, carefully selected for their appearance and durability.
• Batch production: Products like kitchen units, doors, and furniture are made in batches using standardised timber sizes such as MDF or plywood.
• Mass production: Products like flat-pack furniture, packaging, or construction materials are often produced in large volumes using cost-effective materials like chipboard, plywood, or softwoods.

The scale of production influences the cost, material choice, and manufacturing process.

Tools, Equipment, and Processes

Working with timber requires various tools and equipment:

• Hand tools: Saws (e.g., rip or crosscut saws), hammers, and chisels are used for cutting, shaping, and joining wood.
• Power tools: Circular saws, table saws, and jigsaws are commonly used for precise cutting. Planers and routers smooth or shape the wood.
• Machining tools: Woodworking lathes are used to shape timber into curved forms, often used for furniture making.
• Joining tools: Screws, nails, wood glue, and dovetail joints are used for joining pieces of timber together, depending on the product.

Processes like sawing, planing, drilling, sanding, and finishing (e.g., varnishing or painting) are common in woodworking.

Commercial Processes

Timber-based materials undergo several commercial processes to prepare them for use:

• Sawmilling: Logs are cut into planks and beams of various sizes. The process involves sawing, planing, and sometimes drying the timber to reduce moisture content.
• Drying: Timber is kiln-dried to reduce its moisture content and prevent warping or cracking.
• Veneering: Thin slices of wood are peeled or sliced from logs and glued together to create plywood or laminated boards.
• Pressing and bonding: For composite materials like MDF or chipboard, wood fibres are bonded together using resin and pressed into sheets under heat and pressure.
• Finishing: Processes like sanding, staining, varnishing, or lacquering are used to enhance the appearance and durability of timber products.

These processes affect the final characteristics of the timber and are key to producing high-quality, consistent materials.

Summary

Timber-based materials offer a variety of properties suitable for a wide range of design applications. Understanding the properties, selection criteria, ecological impact, and commercial processes is essential for making informed decisions in design and technology. Whether for construction, furniture making, or mass-produced items, timber remains a versatile and renewable resource.