DT Topic 4

Additive Techniques

Additive Techniques

Manufacturing techniques that add material in order to create it

Aesthetic appeal

Favourable in terms of appearance

Aesthetic Characteristics

Aspects of a product that relate to taste, texture, smell and appearance

Air-drying

Air-drying places the stacks of sawn timber in the open or in large sheds hence there is little control over the drying process

Alloy

A mixture that contains at least one metal. This can be a mixture of metals or a mixture of metals and non-metals

Assembly line production

A volume production process where products and components are moved continuously along a conveyor. As the product goes form one work station to another, components are added until the final product is assembled.

Automated production

A volume production process involving machines controlled by computers

Batch production

Limited volume production (a set number of items to be produced)

Bowing

A warp along the length of the face of the wood.

Brittle

Breaks into numerous sharp shards

Composite

A material comprised of two or more constituent materials that have different properties

Compressive Strength

The ability of a material to withstand beings pushed or squashed

Computer numerical control (CNC)

CAD manufacturing. Refers specifically to the computer control of machines for the purpose of manufacturing complex parts in metals and other materials. Machines are controlled by a program commonly called “G code”. Each code is assigned a to a particular operation or process. The codes X, Y, Z movements and feed speeds.

Continuous Flow

A production method used to manufacture, produce or process materials without interruption

Craft Production

A small-scale production process centred on manual skills

Cupping

A warp across the width of the face of wood, in which the edges are higher or lower than the centre.

Density

The mass per unit volume of a material. Its importance is in portability in terms of a product's weight and size. Design contexts include, pre-packaged food (instant noodles) is sold by weight and volume, packaging foams.

Design for disassembly

Designing a product so that when it becomes obsolete it can easily and economically be taken apart, the components reused or repaired, and the materials recycled.

Design for manufacture

Designers design specifically for optimum use of existing manufacturing capability.

Dry rot

When timber is subject to decay and attack by fungus.

Ductility

The ability of a material to be drawn or extruded into a wire or other extended shape.

Elasticity

The extent to which a material will return to its original shape after being deformed.

Electrical insulator

Reduces transmission of electric charge.

Electrical resistivity

The measure of a material's ability to conduct electricity. A material with low resistivity will conduct electricity well.

Equilibrium Moisture Content (EMC)

EMC is at which the moisture content of wood achieves an equilibrium with the environment which can be affected by humidity and temperature

Felting

A method for converting yarn into fabric by matting the fibres together.

First generation robots

A simple mechanical arm that has the ability to make precise motions at high speed. They need constant supervision by a human operator.

Free moisture

The moisture within timber that is contained within the cell cavities and intercellular spaces.

Glass

A hard, brittle and typically transparent amorphous solid made by rapidly cooling a fusion of sand, soda and lime.

Hardness

The resistance a material offers to penetration or scratching.

Hardwood

The wood from a deciduous (broadleaved) tree.

Joining techniques

Methods that are used to join two similar or dissimilar materials together.

Kiln drying

Kiln-drying places the stacks of sawn timber in a kiln, to reduce the moisture content in wood, where the heat, air circulation, and humidity is closely controlled

Kiln seasoning

Thermally insulated chamber, a type of oven, which produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes.

Knitting

A method for converting a yarn into fabric by creating consecutive rows of interlocking loops of yarn.

Knots

Imperfections in timber, caused by the growth of branches in the tree that reduces its strength.

Lamination

Covering the surface of a material with a thin sheet of another material typically for protection, preservation or aesthetic reasons

Magneto-rheostatic

This smart property relates to a fluid that can undergo a dramatic change in its viscosity when exposed to a magnetic field.

Man-made timber

Also known as engineered wood or composite wood, these are wood products that are made by binding or fixing strands, particles of fibres, veneers of boards of wood together with adhesives or other fixing methods to create composite materials. Typical examples include MDF, plywood and chipboard.

Mass

Relates to the amount of matter that is contained with a specific material. It is often confused with weight understandably as we use Kg to measure it. Mass is a constant whereas weight may vary depending upon where it is being measured.

Mass customization

A sophisticated CIM system that manufactures products to individual customer orders. The benefits of economy of scale are gained whether the order is for a single item or for thousands.

Mass production

The production of large amounts of standardized products on production lines, permitting very high rates of production per worker.

Material selection charts

A chart used to identify appropriate materials based on the desired properties.

Mechanical properties

Properties of a material that involve the relationship between stress and strain or a reaction to an applied force.

Mechanized production

A volume production process involving machines controlled by humans.

Multi task robots

A type of robot that can perform more than one task in a manufacturing environment.

Natural fibres

Materials produced by plants or animals that can be spun into a thread, rope or filament.

Non-toxic

Absence of toxic breakdown products/lack of reactivity.

One-off production

An individual (often craft-produced) article or a prototype for larger-scale production.

Oxidization resistance

A property of a metal that means that it does not readily react with oxygen and degrade.

Particle boards

A material made from different sizes of wood chips and joined with glue.

Photochromicity

A property of a smart material. A photochromic material changes colour in response to an increase in light. When the light source is removed, it returns to its original colour.

Physical properties

Any property that is measurable that describes a state of materials, for example, mass, weight, volume and density. These properties tend to be the characteristic of materials that can be identified through non-destructive testing (although some deformation is required to test hardness).

Piezoelectricity

A property of a smart material. A piezoelectric material gives off a small electrical discharge when deformed.

Plasticity

The ability of a material to be changed in shape permanently.

Reforestation

Reforestation is the process of restoring tree cover to areas where woodlands or forest once existed. If this area never returns to its original state of vegetative cover the destructive process is called deforestation.

Seasoning

Seasoning is the commercial drying of timber which reduces the moisture content of wood.

Second generation robots

Robots that are equipped with sensors that can provide information about their surroundings. They can synchronize with each other and do not require constant supervision by a human; however, they are controlled by an external control unit.

Single task robots

Robots that can perform one task only.

Smart material

Materials that have been designed to have one or more properties that can be modified when subject to an external stimuli in a way that the output can be 

Softwood

The wood from a coniferous (evergreen) tree.

Stiffness

The resistance of an elastic body to deflection by an applied force.

Super alloys

An alloy that exhibits excellent mechanical strength, resistance to thermal creep deformation, good surface stability and resistance to corrosion.

Synthetic fibres

Fibres made from a man-made material that are spun into a thread; the joining of monomers into polymers by the process of polymerisation. Examples include polyester, acrylic, nylon, rayon, acetate, spandex, and Kevlar.

Tempering

A heat treating process designed to increase the toughness of an iron-based metal by heating it and allowing it to cool in air. Tempering decreases the hardness of the material, which usually increases the ductility and decreases the brittleness.

Tensile strength

The ability of a material to withstand pulling forces.

Thermal conductivity

The measure of how fast heat is conducted through a slab of material with a given temperature difference across the slab.

Thermal expansion

A measure of the degree of increase in dimensions when an object is heated. This can be measured by an increase in length, area or volume. The expansivity can be measured as the fractional increase in dimension per kelvin increase in temperature.

Thermo-electricity

This refers to a smart material that when heated can produce an electric current. A thermoelectric material is comprised of two dissimilar conductors.

Thermoplastic

A type of plastic that can be heated and formed into a new shape repeatedly.

Thermosetting plastic

A type of plastic that once formed into a shape, cannot be reformed into a different shape.

Third generation robots

Autonomous robots that can operate largely without supervision from a human. They have their own central control unit. Swarms of smaller autonomous robots also fit in this category.

Toughness

The ability of a material to resist the propagation of cracks.

Transparency

Ability to allow light to be transmitted with minimal scattering allowing a clear view through material.

Volume

The quantity of three-dimensional space enclosed by a boundary, for example, the space that a substance solid, liquid, gas, or shape occupies or contains.

Warping

A distortion in wood caused by uneven drying, which results in the material bending or twisting.

Wasting/subtractive techniques

Manufacturing techniques that cut away material in order to create a component.

Weaving

The act of forming a sheet like material by interlacing long threads passing in one direction with others at a right angle to them.

Weight

Relies on mass and gravitational forces to provide measurable value. Weight is technically measure as a force, which is the Newton, i.e. a mass of 1 Kg is equivalent to 9.8 Newton [on earth].

Wood recycling

Wood recycling is the process of turning waste timber into usable products. Recycling timber is a practice that was popularized in the early 1990s as issues such as deforestation and climate change prompted both timber suppliers and consumers to turn to a more sustainable timber source.

Wood treatment

Treatment of wood can involve using solutions, which make the wood poisonous to insects, fungus, and marine borers as well as protecting it from the weather

Work envelope

A fixed 3D space where work activities take place, considering clearance and reach

Work hardening

Also known as strain hardening or cold working, this is a processes of toughening a metal through plastic deformation