Dtech - Unit 4

Mass

Relates to the amount of matter that is contained within a specific material. Mass is a constant, often confused with weight.

Weight

Relies on mass and gravitational forces. Measured as a force in Newtons, where 1 Kg equals 9.8 Newtons on Earth.

Volume

The amount of three-dimensional space enclosed by a material, such as a solid, liquid, or gas.

Density

The mass per unit volume of a material. Important for weight and size in design contexts, like pre-packaged food and packaging materials.

Electrical Resistivity

A material's ability to conduct electricity. Low resistivity means good electrical conduction, important for selecting conductors or insulators.

Electrical Insulator

Reduces transmission of electric charge, used in electrical plugs.

Thermal Conductivity

Measures how fast heat is conducted through a material. Important for objects that need heat insulation or conduction, such as pots and pans.

Thermal Expansion (Expansivity)

A material's dimensional increase when heated. Relevant when dissimilar materials are joined, like in oven doors or glass pot lids with metal rims.

Hardness

Resistance to scratching or penetration, important in materials like ceramic floor tiles.

Tensile Strength

Ability to withstand pulling forces, crucial for materials like ropes, cables, and fishing lines.

Compressive Strength

Ability to withstand being squashed, found in materials like concrete or bricks.

Stiffness

Resistance to deflection under force, important for objects like aircraft wings or car panels.

Toughness

Ability to resist crack propagation, important for materials subjected to impact, such as automobile bumpers.

Brittleness

Tendency to break into sharp shards, like glass.

Ductility

Ability to be drawn into wires or extended shapes, important in metals used for extrusions.

Stress

The force on a material divided by its cross-sectional area.

Strain

Material's deformation response to stress, defined as the change in length divided by the original length.

Young's Modulus

Measures the stiffness of an elastic material as stress divided by strain.

Elasticity

Extent to which a material returns to its original shape after deformation.

Plasticity

Ability of a material to be permanently deformed without breaking, like after reaching its yield point.

Aesthetic Characteristics

Elements like taste, texture, smell, appearance, and color that make a product visually or sensorially appealing.

Piezoelectricity

Materials that produce a small electric discharge when deformed, used in sensors like car airbags.

Shape Memory Alloys (SMA)

Metals that return to their original shape after deformation, used in glasses frames and robotic limbs.

Photochromicity

Materials that change color when exposed to light, such as color-changing sunglass lenses.

Magneto-rheostatic & Electro-rheostatic

Fluids that change viscosity when exposed to magnetic or electric fields, used in shock absorbers and prosthetic limbs.

Thermoelectricity

Direct production of electricity from heat, used in remote areas or space probes for power.

Grain Size (Metals)

Metals have crystalline structures made of grains. Grain size can be modified through heat treatment, influencing properties such as tensile strength, toughness, ductility, brittleness, and flexibility.

Alloying

A process of mixing metals or metals with non-metals to enhance strength and hardness while reducing malleability and ductility.

Work Hardening (Cold Working)

Toughens metals through plastic deformation, such as twisting or bending.

Tempering

Heat treatment that increases toughness and ductility while reducing hardness and brittleness after a metal has been hardened.

Superalloys

High-performance alloys used in aerospace and chemical industries, known for mechanical strength, thermal creep resistance, surface stability, and oxidation resistance.

Creep

The slow, permanent deformation of metals under stress at high temperatures over long periods.

Oxidation Resistance

Ability of a material to resist the corrosive effects of oxygen, such as rust formation.

Recovery and Disposal of Metals

Metals are recyclable, reducing environmental impact and energy usage. Recycled metals like aluminum save up to 95% energy.

Ferrous Alloys

Contain iron, making them magnetic. Examples include Mild Steel, Stainless Steel, and Cast Iron.

Non-Ferrous Alloys

Contain no iron. Examples include Aluminum, Copper, Brass, Silver, and Lead.

Equilibrium Moisture Content (EMC)

The moisture content of wood at equilibrium with the local environment, affected by humidity and temperature.

Kiln Seasoning

Drying timber in a thermally insulated chamber, closely controlling heat, air circulation, and humidity.

Air-Drying

Stacking sawn timber in the open or large sheds with little control over the drying process.

Kiln-Drying

Stacking sawn timber in a kiln with controlled heat, air circulation, and humidity to reduce moisture content.

Bowing

Warping along the length of the face of the wood.

Cupping

Warping across the width of the face of wood, with edges higher or lower than the center.

Twisting

Warping where the two ends of the material do not lie on the same plane.

Knots

Imperfections in timber from branch growth, reducing its strength.

Natural Timber

Timber sawn from trees and used as is, including hardwood and softwood.

Hardwood Trees

Wood from deciduous (broadleaved) trees, including eucalyptus, elm, maple, oak, and beech.

Softwood Trees

Wood from coniferous (evergreen) trees, including pine, cedar, and cypress.

Plywood

Layers of veneers glued together perpendicularly.

Particle Board

Made from wood chips joined with glue and pressed.

MDF (Medium Density Fibre Board)

Strands of fiber glued and pressed into sheets.

Lamination

Covering the surface with a thin sheet of another material for protection or aesthetics.

Wood Recycling

The process of turning waste timber into usable products.

Glass

A transparent, brittle material made primarily from silica sand, limestone, and soda ash, which is melted at high temperatures for use in various applications.

Soda Glass

The most widely used type of glass, known for its versatility and common applications, including window panes, glassware, and drink bottles, with medium thermal shock resistance.

Borosilicate Glass (Pyrex)

A type of glass modified with oxides to enhance thermal resistance, making it suitable for laboratory equipment and cookware that require heat stability.

Toughened Glass

Glass that undergoes thermal treatment to increase its strength, causing it to break into small, safer pieces instead of sharp shards, commonly used in car windows and shower doors.

Laminated Glass

A composite glass made by sandwiching layers of plastic between glass sheets, providing safety by holding shards together when broken, used in bulletproof applications and vehicle windscreens.

Glass Fibre

Thin strands of glass that can be woven into mats, often used in composite materials when combined with resin, applicable in construction and manufacturing for lightweight yet strong components.

Petrochemicals

Primary raw materials used to produce most modern plastics, derived from oil.

Bioplastics

Plastics made from renewable resources (e.g., corn or potato starch) that degrade under certain conditions but may not fully break down.

Thermoplastics

Plastics that can be reshaped upon heating due to weak secondary bonds between chains, allowing for easy manufacturing and recycling.

Thermosets

Plastics with strong primary bonds that create a rigid 3D structure, which cannot be reheated or remolded after curing.

Epoxy Resin

A thermoset known for high thermal and chemical resistance, widely used in adhesives and electrical insulators.

Cullet

Recycled glass that is added to new raw materials to produce new glass, reducing energy consumption and environmental impact.

Textiles Industry

A sector that evolves continuously, encompassing both technical textiles and traditional clothing applications.

Natural Fibres

Materials sourced from plants or animals that can be spun into threads, ropes, or filaments, such as wool, cotton, and silk.

Synthetic Fibres

Man-made materials created through the polymerization process, resulting in fibers like acrylic, nylon, polyester, and Kevlar.

Weaving

The process of creating fabric by interlacing threads in perpendicular directions to form a sheet-like material.

Knitting

A method for transforming yarn into fabric by interlocking loops of yarn in consecutive rows.

Smart Textiles

Innovative textiles that incorporate technology for advanced functionality, applicable in various fields like sportswear and aerospace.

Carbon Fibre

A strong and lightweight reinforcement used in composites, significant for weight reduction in vehicles and aircraft.

Scale of Production

Decisions influenced by volume, material types, product type, staffing, resources, and finance.

Mass Customization

A production approach that allows consumers to customize products, making them unique.

Craft Production

A small-scale production process centered on manual skills.

Mechanized Production

A volume production process involving machines controlled by humans.

Automated Production

A volume production process involving machines controlled by production computers.

One-off Production

Individual products or prototypes made often with craft production techniques, focusing on user needs.

Batch Production

A limited production run where products are made in batches rather than continuous production.

Mass Production

The production of large amounts of standardized products on production lines for high production rates.

Continuous Flow Production

A production method for manufacturing without interruption, producing thousands of standardized products continuously.

Design for Manufacture (DfM)

Designing products specifically for optimal use of existing manufacturing capabilities.

Machining

The removal of material by a tool that moves across the material, often using CNC machinery.

Turning

A process where material is held and rotated while a tool removes material to shape cylindrical objects.

Milling

A machining method where a rotating cutting tool removes material from a stationary workpiece.

Drilling

The process of boring holes into material using a rotating drill bit.

Abrading

Wearing away material using abrasive materials to achieve smooth surfaces.

Moulding

Heating materials until pliable, then placing them into moulds to form desired shapes.

Injection Moulding

A method where molten plastic is injected into a mould to create plastic parts efficiently.

Blow Moulding

A process that inflates hot thermoplastic inside a mould to create hollow objects.

Rotational Moulding

Heating and rotating a mould to evenly distribute thermoplastic and create hollow products.

Compression Moulding

Placing heated, pliable material in an open mould that closes to shape it.

Thermoforming

Heating a plastic sheet until pliable, then forming it in a mould, often using vacuum forming.

Permanent Joining Techniques

Methods for joining materials that create a permanent bond, including adhesives and welding.

Temporary Joining Techniques

Methods that allow materials to be joined but can be easily undone, such as screws and bolts.

Fasteners (Permanent)

Devices like nails or rivets used to permanently join materials together.

Fasteners (Temporary)

Devices like screws or bolts used to join materials that can be disassembled when needed.

Appropriate Manufacturing Techniques

Selection criteria for manufacturing methods based on material characteristics, cost, scale, and desired properties.

Economies of Scale

As a business grows and produces more units, it aims to achieve economies of scale, which means a decrease in average production costs.

Computer Numerical Control (CNC)

A type of automated production that uses computers to control machines. CNC machines are programmed with specific instructions to create complex shapes and parts.

Assembly Line Production

A high-volume production process where products are moved along a conveyor belt and assembled at different stations.