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AQA A-level Design & Technology / Product Design⌕ Search notes
AQA 7552   /   3.1.4

Woods.

Forming, redistribution and addition processes · Technical principles

Revision notes

Wood Processes

Steam Bending

Steam bending reshapes solid timber using heat and moisture to soften the lignin that bonds wood fibres.

Timber is placed in a sealed steam box where it absorbs heat and moisture, making the fibres flexible.

The softened wood is bent immediately around a former or jig and clamped securely.

As the wood cools and dries, it retains the new shape.

Straight-grained, seasoned (not kiln-dried) hardwoods such as oak and ash are most suitable.

Advantages

Fibres remain continuous, maintaining strength.

Produces smooth, attractive curves.

No material removal.

Suitable for thick sections.

Disadvantages

Time consuming and requires specialist setup.

Risk of splitting on the outer radius.

Spring-back can occur if not clamped long enough.

Limited to suitable timber species.

Laminating

Laminating creates curved or strong components by bonding thin layers of wood together.

Thin veneers or strips are glued together with the grain aligned, then bent over a former.

Pressure is applied using clamps or a vacuum press until the adhesive cures.

The layered structure increases strength and reduces movement.

Once cured, excess material is trimmed and the component is finished.

Advantages

Very strong and dimensionally stable.

Allows complex, repeatable curved forms.

High-quality aesthetic finish.

Suitable for batch production.

Disadvantages

Time consuming.

Requires accurate formers and clamping.

Risk of delamination if adhesive fails.

Glue lines may be visible.

WASTING / MACHINING PROCESSES

Turning (Lathe Work)

Turning shapes timber by rotating it against hand tools on a lathe.

The workpiece is secured between centres, on a faceplate, or in a chuck depending on the form required.

Cutting tools such as gouges and chisels remove material to create cylindrical or symmetrical forms.

Sanding and finishing are often carried out while the workpiece is rotating.

Common products include chair legs, spindles, bowls and handles.

Advantages

Produces smooth, symmetrical components.

Fast once set up.

High-quality surface finish.

Disadvantages

Limited to rotational forms.

Requires skill and training.

Safety risks if work is poorly secured.

Routing

Routing removes material using a high-speed rotating cutter.

A router is guided along the workpiece manually or using a jig to cut grooves, rebates or decorative edges.

The depth of cut and cutter profile determine the final shape.

Can be done using manual routers or CNC routers for increased accuracy.

Advantages

Accurate and repeatable.

Suitable for complex edge profiles.

Can be automated using CNC.

Disadvantages

Noisy and dusty.

Risk of tear-out.

Requires careful control.

CNC Routing / Milling

CNC machines automate machining using CAD/CAM systems.

A 2D or 3D CAD model is converted into a CNC toolpath.

The material is fixed to the machine bed and the program controls cutter movement.

CNC is commonly used for panels, joints, decorative features and batch production.

Advantages

Very high accuracy and repeatability.

Complex shapes possible.

Ideal for batch and mass production.

Disadvantages

Expensive equipment.

Skilled programming required.

Errors are repeated if the file is incorrect.

ADDITION / FABRICATION PROCESSES

Traditional Wood Joints

Traditional joints rely on surface area and glue strength.

The greater the gluing area, the stronger the joint.

Used mainly with solid timber.

Examples include dovetail, mortise and tenon, housing and finger joints.

KNOCK-DOWN (KD) FITTINGS

KD fittings are temporary mechanical joints used primarily in flat-pack furniture.

Why KD fittings are used

Sheet materials such as MDF and chipboard are weak in tension and unsuitable for traditional joints.

Products must be transported flat to reduce storage and shipping costs.

Assembly must be possible by the consumer using basic tools.

Standardised fittings allow mass production and interchangeability.

Cam-lock connectors

Cam-lock connectors consist of a metal cam and a steel dowel.

The dowel is screwed into one panel and inserted into a hole in the second panel.

A circular cam is inserted into a pre-drilled recess.

When turned with a screwdriver, the cam pulls the dowel tight, locking the panels together.

Widely used in flat-pack furniture such as bookcases and wardrobes.

Advantages

Quick assembly.

Hidden fixing improves appearance.

Strong for panel-based construction.

Disadvantages

Precision drilling required.

Can loosen with repeated assembly.

Limited resistance to racking forces.

Barrel nut and bolt

A barrel nut is a cylindrical nut inserted into a cross-drilled hole.

A bolt passes through one panel and screws into the barrel nut.

Tightening pulls the two components together at right angles.

Commonly used in bed frames and furniture requiring repeated dismantling.

Advantages

Strong mechanical joint.

Can be dismantled and reassembled.

Suitable for thicker panels.

Disadvantages

Visible fixings.

Requires accurate drilling.

Can loosen over time.

Modesty blocks

Modesty blocks are small moulded plastic blocks fixed inside corners.

Screws pass through the block into both panels.

Spread the load and prevent screw pull-out in chipboard.

Common in cabinets and kitchen units.

Advantages

Simple and cheap.

Reduces damage to panels.

Easy to assemble.

Disadvantages

Visible internally.

Limited structural strength.

Lower quality feel.

Screws

Screws provide direct mechanical fixing.

Pilot holes prevent splitting.

Clearance holes allow panels to pull together.

Countersinking allows flush finishes.

Advantages

Immediate strength.

Easy to assemble and disassemble.

Disadvantages

Visible fixings.

Risk of splitting if poorly prepared

Wood Processes

Wood processes

Wood manufacturing processes can be grouped into:

Addition / fabrication

Forming

Machining
Wasting
(not shown on this page but examinable)

Production methods vary depending on product type and scale of manufacture.

Addition / fabrication processes

Traditional wood jointing

Joint strength increases with greater glued contact area

Joints are selected based on strength requirements, appearance, and production method

Common joints and uses

Dovetail joint – drawers; strong in multiple directions

Comb / finger joint – box construction; large glue area

Housing joint – framework, cabinets, shelving

Half-lap joint – simple frames or boxes

Dowel joint – flat-pack furniture (bookcases, wardrobes)

Mortise and tenon joint – frame construction (tables, chairs); high strength

Component jointing (KD fittings)

Knock-down (KD) fittings

Used in flat-pack furniture

Require few simple tools

Standardised and interchangeable, allowing mass production and easy assembly

Types of KD fittings

Modesty blocks

Small rigid polymer blocks

Moulded holes take screws

Used to join panels in cupboards and storage units

Barrel nuts and bolts

Use a cross-dowel inserted into one component

Bolt passes through the second component and tightens into the cross-dowel

Typically tightened with an Allen key

Commonly used in bed frames

Cam-lock connectors

Metal dowel screws into one component

Cam (disk) fits into a pre-drilled hole

Rotating the cam pulls components tightly together

Widely used in flat-pack furniture (e.g. bookcases)

Wood screws

Used when thread is needed only in the lower component

Clearance hole in top piece

Pilot hole (smaller than thread) in bottom piece for grip

Coach bolts

Domed head with square section beneath

Square section bites into timber to prevent rotation

Used for door furniture and street furniture

Forming processes

Uses heat and steam to soften wood fibres

Lamination

Bonds layers of veneers or thin boards (e.g. 3 mm plywood)

Layers are glued and bent over a former

Once dry, layers form a strong, shaped component

Held during curing using clamps or vacuum bags

Steam bending

Wood is placed in a steam box

Bent over a former and clamped until dry

Quicker and less wasteful than lamination

Lamination requires glue curing time and trimming

Machine processes

Turning

Wood is machined on a lathe.

Methods

Turning between centres – spindles (chair and table legs)

Turning on a faceplate – bowls, domes

Turning in a chuck – gripping work to machine ends or internal surfaces

Milling (A-level only)

Used for small, basic machining tasks

Suitable for rough prototypes or small holes/channels

Slower process than CNC routing

Smaller working area than CNC routers

Can be manual or CNC

Routing

Used to cut slots, holes, and decorative mouldings

Common on edges (e.g. table tops)

Can be manual (plunge router) or CNC

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