Glossary

Additive:

Something that is added to another. In materials science, it describes a substance that is added to another substance to improve it. 

Additive manufacturing:

Additive manufacturing is when products are made by adding on material sequentially, usually in layers, as in techniques like 3D modelling or rapid prototyping.

Aerospace:

Technology dedicated to aircraft or spacecraft.

Aesthetics:

In design, aesthetics covers the look of the product in terms of style, beauty or attractiveness.

Alloy:

A metallic substance composed of two or more elements.

Boundary:

An extent or constraint that forms a border. Examples of usage include boundary conditions and systems boundary. The perimeter of a material grain (crystal) is referred to as its grain boundary.

Casting:

A fabrication process where molten material is poured into a mould cavity and allowed to solidify, taking the shape of the mould. Compacted sand is often used as the mould material. Materials made by casting include metals, polymers and, less commonly, ceramics.

Ceramic:

Brittle materials made up of both metallic and non-metallic elements. Ceramics exhibit strong ionic and/or covalent bonding, resulting in properties such as high hardness and stiffness, low ductility and low thermal and electrical conductivity. This category covers a diverse range of materials, including  traditional ceramics such as clay-based pottery, tiles, linings for furnaces and kilns, etc., through to industrial ceramics such as insulators for electronic components, and cutting tools and knives.

Component:

A part, often in a system of parts. The system could be mechanical, for example a girder in a bridge or a shaft in a gearbox. Or it could be electrical – a resistor in an electronic circuit – or chemical – an element in an alloy system.

Computer-aided design:

A computer-assisted method of producing 2D drawings and 3D models for design and manufacture. 3D CAD models are digital representations of forms or products.

Cost:

Expenses, overheads or the price of a product or service.

Crystal:

A solid material composed of a lattice of atoms arranged in a regular and symmetrical pattern.

Cutting:

The separation of something into two parts with the aid of a sharp blade or other tool. A manufacturing process that includes procedures such as milling, grinding and machining. Cutting can be done using knife blades, cutting tools or instruments, lasers and ion beams.

Deformation:

Deformation occurs when a material under stress changes shape, either temporarily (elastically) or permanently (plastically). The amount of deformation a material experiences depends on the level of stress being applied. If a material is stressed to a point under its yield strength, it undergoes elastic deformation and the original shape is recoverable once the load is removed. If the material is stressed to a point beyond its yield strength, it experiences plastic deformation and the material remains permanently deformed, even after the stress is removed.

Density:

A material property of solids, liquids and gases. Density is a measure of the mass of the material per unit volume (kg/m³).

Deposition:

A term used in surface engineering to describe the application of a deposit onto a surface. For example, a coating or surface finish to solids, a physical vapour deposition or plasma coating.

Design:

The origination and planning involved in creating a new product, system or procedure, taking into account form, fit and function, including aesthetics and ergonomics. Other contributing factors to be considered when designing are related to innovation, market forces and costings, to name but three.

Die:

Another word for a mould or casting. Also used to describe the metal block used in ‘punch and die’ forming of sheet metal.

Drawn:

A description of something having been pulled through, as in drawing a metal rod through a die to reduce its cross section. Generally applied to the output from any process known as ‘drawing’.

Electron:

A low-mass sub-atomic particle that encircles the nucleus. Electrons carry a negative electrical charge. In materials that are good conductors of electricity, such as metals, electrons can exist independently of atoms. These are known as free or valence electrons.

Energy:

The capacity of a body to do work. Measured in joules (J). Types of energy include kinetic, potential, thermal, electrical, chemical and nuclear.

Forging:

A manufacturing process that involves using hammers or hydraulic presses to form malleable metals. Most forging is done under extreme heat at temperatures up to 1250°C, although cold forging is also carried out, as is open die forging, closed die forging and impression die forging.

Forming:

A manufacturing process that changes material in the solid state into a required shape, such as sheet, rod or bar. The choice of forming process is dependent on the geometry and microstructure of the material. Examples of forming processes are rolling, extruding, drawing and forging.

Function:

The purpose or main use of a product or service. In mathematics, a function describes an expression or rule that defines a relationship between one variable and another, as is shown on the x and y axes of a graph.

Functional:

Something working as it is meant to. Fit for purpose. The term functional is also used to describe an item or operation as practical or utilitarian, rather than attractive.

Geometry:

The shape and relative arrangement of constituent parts. The study of the relationship between points, lines, areas and volumes in shapes of two or three dimensions.

Grain:

An individual crystal in the microstructure of a polycrystalline material. The structure and size of grains have an influence on the properties of a solid material. Can also be a single grain of powder or sand. In the structure of wood, ‘the grain’ describes the direction in which the fibrils are growing.

Grain growth:

The final stage of annealing in metals, in which stress-free recrystallised grains expand to replace the remaining distorted grains within the microstructure, resulting in maximal softening of the material.

Inclusions:

Discrete particles of impurities within a solid metal alloy, most often introduced during previous melting and casting. Inclusions of metal oxides and sulphides are often clearly visible under the optical microscope, especially when examining specimens in the unetched state. Inclusions may have an adverse effect on the mechanical properties of a material in service, so levels of inclusions are minimised where possible during manufacture. Certain inclusions, such as manganese sulphide or lead, are deliberately created in some alloy grades in order to enhance machinability.

Injection:

An insertion or inoculation. A substance is inserted under pressure through a small orifice, as in an injection moulding process or a medical vaccination.

Joining:

Mechanical processes that involve connecting two or more solid parts together. Examples include welding, brazing, soldering, gluing and fastening.

Laser:

An acronym for Light Amplification by Stimulated Emission of Radiation. A term used to describe a device that emits a narrow beam of coherent light.

Liquid:

One of the three principal states of matter, it is the state between a solid and a gas. A liquid flows and, when contained, conforms to the shape of its container. A liquid is generally incompressible.

Load:

Mechanical force applied to a body

Manufacturing process:

The range of processes that an item might undergo during its production, before it reaches its final form as a finished, marketable product. Physical manufacturing processes used during production might include cutting, forming, extrusion, casting, injection moulding, joining, painting, etc. The term can also be used to describe how production will be handled in terms of which manufacturing system will best suit the volume of products and the budget, e.g. bespoke, batch, line or continuous.

Material:

Matter. A substance or substances out of which something can be made. Man-made materials include metals, ceramics, polymers, composites and fabrics. Organic materials include wood, stone, bone and leather.

Measurement:

The act of determining the size, amount or value of something with an appropriate instrument. 

Melting:

When a material exposed to an increase in temperature turns from a solid to a liquid. 

Metals:

Materials comprising elements in the periodic table that have loosely bound electrons in their outermost atomic shell. These mobile electrons serve to bond metal atoms together, while conferring the characteristic metallic properties of high thermal and electrical conductivity. Metals can be mixed with other metals and non-metals to make alloys. 

Microstructural:

Describes a material structure at microscopic scale.

Microstructure:

The structural features of an item or a material at a scale that cannot be seen by eye, but can be easily viewed under a microscope, i.e. a scale at which material grains and phases can be observed.

Mould:

Receptacle into which liquid is poured pending subsequent solidification.

Moulding:

A form or structure that has been moulded or cast in a mould or die. Examples of moulding processes are injection moulding, compressive moulding, vacuum-sealed moulding, blow moulding rotational moulding and transfer moulding. Term most often applied to polymers and glass.

Nickel:

A hard corrosion-resistant metal often used to plate other metals giving a protective coating. Also used in the alloying of stainless steel. Widely used in the manufacture of superalloys for turbine blades operating at high temperatures. Also used in the manufacture of batteries and coins. Traces in glass lend it a green colour.

Phase:

A stage or a step in a process.  In materials science, phase can refer to a state of matter, as in liquid phase, solid phase and gas phase. Phase diagrams show different material phases as a function of composition and temperature.

Plane:

A flat surface where the radius of curvature is infinite at all points.

Plastic:

The word plastic can be used to describe the type of irreversible material deformation that occurs once a material is beyond its yield point. As in plastic deformation, plastic strain and plastic flow. Plastic is also a generic term for man-made polymeric materials such as thermoplastics and thermosetting polymers. Examples include polyethylene, polypropylene, polystyrene, polycarbonates, polyesters and polyurethanes.

Polymer:

Substance that has a structure of many molecules bonded together in repeated linked units or chains. Polymers can be organic, synthetic or a mix of the two. Synthetic thermoplastic polymers consist of long chains of molecules, while thermoset polymers are composed of 3D networks of molecules. Other synthetic polymer groups include elastomers and fibres. Some polymers occur naturally, such as the polysaccharide cellulose, and proteins, which are formed from amino acids.

Pores:

Holes, gaps or voids in a solid material. Pores can occur on the surface as well as within the bulk of a material. Liquid and gas can enter via pores. See porosity.

Porosity:

Holes, open pores or void spaces within the microstructure of a solid make a material porous, and therefore prone to absorption of liquid or gas. Porosity is the measure of how porous a material is, as defined by the volume of pores per unit volume of material. It is generally an undesirable property, as it can promote oxidation and corrosion and the pores can act as crack nucleation points. Porosity can occur in both metals and polymers during casting. In powder processing, pores can exist between the powder particles prior to compaction, and it is common for some residual porosity to remain even after densification.

Powder:

Loose particles of dry, granular, solid material.

Power:

n physics, power is the rate of doing work (energy used/time). The SI unit for power is the watt (W); one watt is equivalent to a work rate of 1 Joule per second. In mathematics, a power (exponent) defines how many times the base number should be multiplied by itself, e.g. ten to the power two equals 100 (10² = 100).

Precision:

High levels of accuracy. Finely tuned. Has the quality of being precise or exact. Precision engineering involves the design and manufacture of components and assemblies with high accuracy and tight tolerances on dimensions. Mathematically, increasing precision is commonly associated with an increased number of decimal places.

Principles:

A code of ethics or standards applied. For instance, in scientific research, there are unwritten scientific principles that involve acting with honesty and integrity within the field of research.

Process:

Another word for a procedure, an operation or an activity. The term process control refers to keeping all processes under control and within set limits. This control could be in terms of output levels, temperature, pressure and flow.

Product:

Something that is produced. It might be a commodity, a physical item that has been manufactured, an idea or a service or any combination. A product can also refer to something that has evolved or resulted from something else, for example ‘Siliceous stones such as granite and basalt are the direct product of high-temperature geological processes below the earth's crust’.

Prototype:

An early model or first build of a product design. From a prototype, a product can be tested, evaluated or even promoted, prior to formal manufacture.

Quenching:

An important hardening process for steels or metal alloys. Quenching is the rapid cooling of heated metal in a cooling agent, usually water, but can be in air, oil or brine. When steel is cooled rapidly, the carbon atoms do not have time to form the equilibrium phase, cementite, instead causing the austenite to undergo a shear transformation to martensite, preventing the movement of dislocations, hardening the metal and making it brittle.

Raw material:

Unprocessed feedstock. Anything that can be sourced and, often together with other raw materials, converted into a product.

Resin:

A widely used term to describe a viscous liquid or a solid non-crystalline polymer. There are two main classes of synthetic resins, thermoplastic resins, which can be softened and reformed by heating, and thermosetting resins, which remain in the solid state when heated. Natural organic resins are extracted as fluid secretions from trees, particularly pine and firs. They are commonly used in medical balsams and toiletries such as soap. Synthetic resins, sometimes mixed with natural resins, are used in industrial solvents, varnishes, lacquers and adhesives.

Roughness:

Roughness is not always a disadvantage; a rough surface can promote adhesion, for example to help paint grip to the surface or to provide traction in moving parts. Roughness is distinguished from waviness by its shorter wavelength.

Sheet:

An object displaying large dimensions in two orthogonal directions, but a comparatively small dimension in the third mutually orthogonal direction. An object with a continuous thin cross section. In metal production, sheet is generally much thinner than plate, exhibiting a level of flexibility that permits it to be coiled.

Solid:

State of matter that retains its shape and volume when acted upon by external forces. Solids do not generally flow like liquids or diffuse like gases. Solids can be cut or shaped. Solids include powders and solid particles of materials like salt and sand.

Solidification:

The process in which a liquid transforms into a solid upon cooling, often involving steps of nucleation and growth.

State:

A condition or circumstance. The four physical states of matter comprise solid, liquid, gas and plasma.

Stereolithography:

A process that starts from a digital 3D image. In a bath of liquid polymer, the 3D part itself is built up in layers and incrementally solidifies when it is struck by an ultraviolet laser beam. Stereolithography is an example of additive manufacturing.

Stress:

Defined as a measure of force per unit area (σ = F/A). There are different types of stress. Examples include compressive stress, tensile stress and shear stress. Stresses locked into a component or assembly, subsequent to manufacturing processes such as welding or shot-peening, are known as residual stresses. Limiting values of stress may be defined for a material, such as yield stress and ultimate tensile stress.

Substrate:

An underlying substance or layer. The bulk material that lies directly underneath a thinner applied coating. Can also refer to the base material from which oxide layers grow, as in the corrosion process affecting certain metals; the bulk metal is termed the substrate, while the oxide layer forms on top.

Surface:

The outside part or uppermost layer of something. A boundary between one phase and another.

Temperature:

The degree or intensity of heat in a substance or an object. Temperature can be measured in degrees Fahrenheit (°F), degrees Celsius (°C) or Kelvin (K). Readings are taken from a thermometer.

Tensile:

Under tension; being pulled apart. Being elongated or stretched.

Thermal:

Related to heat. Thermal energy comes from heat generated by the movement of particles inside a substance.

Titanium:

A low-density refractory metal with a high strength-to-weight ratio and excellent resistance to corrosion, making it ideal for use in aqueous environments. Used in aerospace and ship-building applications. Titanium is the material most often used in biomedical applications, such as in the manufacture of prosthetics. Also used as a minor alloying element in some stainless steels.

Tool:

A physical device or instrument that makes it easier to carry out a mechanical procedure or to alter or make something. A mechanical tool can be hand-held, like a screwdriver or hammer, or machine-driven, like a milling machine or an automated cutting machine. Non-mechanical tools could relate to anything that makes a process easier, for example analytical tools and software tools.

Turbine:

A machine made from contoured propeller type blades, fins, vanes or sails fixed to a rotating shaft or axis (rotor). The rotating blades of a turbine work to convert kinetic energy, from moving water or air, into power. Examples of turbines range from traditional windmills and watermill wheels that provide energy to drive attached grain mills, through to the turbines used to operate hydroelectric power generators or the gas turbines that power jet engines. Modern-day wind turbines and water turbines help to produce renewable energy.

Vacuum:

A region or space that is entirely free of matter. An approximation to such a vacuum is a region in which the gaseous pressure is much lower than atmospheric pressure. High vacuum is characterised by pressures in the range 10⁻⁵ to 10⁻⁹ mbar. Ultrahigh vacuum has pressures lower than 10⁻⁹ mbar.

Wetting:

Wetting is used to describe how much wettability a solid material has, according to how much surface tension exists at the solid’s surface.  Using the example of a droplet of liquid (including adhesives) on a perfectly flat surface, the degree of wetting is calculated from the wetting angle (α), taken from the intersection point where the liquid, solid surface and air meet. The angle is formed between the horizontal surface of the solid, and an imaginary line at a tangent with the curved surface of the droplet. The diagram below shows the concept and loosely describes how the wetting angle relates to a material’s wettability. Furthermore, the surface tension or surface free energy can also be calculated from the wetting angle by using Young’s equation. In casting, penetration of the molten material into the mould material is also called wetting. It reflects a surface reaction between the hot liquid and the sand used to make the mould or core. This makes it difficult to remove the solidified cast from the mould, and gives a poor surface finish.

Workpiece:

A piece being worked on. It is used to describe an item or component undergoing a manufacturing process, such as parts being welded or machined.

Yield:

When a material under increasing applied stress reaches a point where elastic strain is supplemented by irreversible plastic strain, the material may be said to have yielded. In manufacturing, the yield of a process refers to an output of production or supply and can be quantified as the ratio of (materials output as acceptable product) ÷ (materials input) × 100 %.