Updated on 07 July 2025

Aluminium is everywhere, from the bauxite mines to the sleek products we use daily. But how well do we understand the journey of this versatile metal? That’s where AL Pedia, a knowledge hub under AL Learn, comes in.

Through AL Pedia, we’re building an easy-to-follow A-Z encyclopedia of aluminium, covering key terms from across the aluminium value chain. Whether a student, a professional, or simply curious about the industry, this is your go-to space for breaking down complex concepts into simple and digestible insights.

Each week, we update 10 key terminologies, starting with the basics like Bauxite, Alumina, and Aluminium, and gradually moving through the refining, production, and downstream processes. You can find these posts on our Instagram and LinkedIn pages, making learning accessible anytime, anywhere.

A

• Aluminium: Aluminium is a lightweight, durable and infinitely recyclable metal that plays a vital role in modern industrial and sustainable development.
• Abrasions: Abrasions are surface scratches or scuff marks that occur on aluminium during handling, fabrication, or finishing processes. These imperfections can affect the aesthetic quality and may require polishing or refinishing in architectural and decorative applications.
• Adaptation: Adaptation in the context of aluminium production refers to modifying systems and processes to cope with climate change. This includes using more resilient infrastructure, switching to low-emission inputs and integrating sustainable practices to ensure long-term industry viability amid evolving climate challenges.
• Age hardening: Age hardening, also known as precipitation hardening, is a heat treatment process that strengthens aluminium alloys by forming fine particles within the metal’s structure. This method enhances the mechanical properties of aluminium, making it ideal for aerospace, automotive and structural applications.
• Age Softening: Age softening is a phenomenon where aluminium alloys, particularly heat-treatable ones, gradually lose their mechanical strength over time at room or elevated temperatures. This property is critical to consider in applications requiring long-term structural integrity, such as aerospace and marine environments.
• Ageing Precipitation: Ageing precipitation, also called precipitation ageing, is a heat treatment process where fine particles form within aluminium alloys over time, enhancing hardness and strength. This controlled process is widely used in aerospace and automotive industries for high-performance components.
• Alloy: An alloy is a metallic substance formed by combining aluminium with other elements to enhance strength, durability, and performance for specific applications.
• Alumina: Alumina, or aluminium oxide, is a white crystalline substance refined from bauxite and serves as the primary raw material for aluminium production.
• Anodising: Anodising is an electrochemical process that forms a protective oxide layer on aluminium, improving its corrosion resistance, surface hardness, and aesthetic appeal.
• Aluminium Oxide: Aluminium oxide (Al₂O₃) is a naturally occurring, hard and chemically resistant compound used in aluminium production and as an abrasive or ceramic material. It also forms a protective layer on aluminium surfaces, enhancing corrosion resistance.
• Aluminium Angle: Aluminium angle is a product which has two legs to form a 90-degree angle. It serves well both as structural material and trim. Beyond the inherent strength of the angle shape, the aluminium provides its inherent strength, corrosion resistance and lightweight.
• Angularity: Angularity refers to the sharpness or degree of corner definition in aluminium extrusions or machined parts. It impacts the fit, form and aesthetic quality of components, especially in architectural and precision engineering applications.
• Anodic Film: An anodic film is the protective oxide layer formed on aluminium surfaces during anodising. This layer enhances corrosion resistance, wear resistance, and provides an excellent base for dyeing, making it suitable for architectural and consumer product finishes.
• Anodised Aluminium: Anodised aluminium is aluminium that has undergone an electrolytic process to form a thick, protective oxide layer. This layer enhances corrosion resistance, surface hardness and aesthetic appeal and can be dyed in various colours.

B

• Bauxite: Bauxite is the primary ore of aluminium, rich in aluminium hydroxide minerals and essential for aluminium production.
• Bayer Process: The Bayer Process is the principal industrial method for refining bauxite into alumina through caustic digestion, clarification, precipitation and calcination.
• Billet: A billet is a solid, semi-finished aluminium product with a cylindrical shape, used as feedstock for extrusion, forging, or rolling processes.
• Bolster: A bolster is a tooling component used in aluminium extrusion dies to support and align the die stack. It ensures even pressure distribution during the extrusion process, contributing to product consistency and die life.
• Bow: Bow refers to a curvature or deviation from flatness in aluminium sheets or extrusions. It often arises during rolling or extrusion and can affect fit and performance in precision engineering or construction applications.
• Bright Anodised Aluminium: Bright anodised aluminium refers to aluminium that has been chemically brightened and anodised to achieve a highly reflective, mirror-like finish. It is widely used in decorative and architectural applications.
• Bright Dipping: Bright dipping is a chemical treatment applied to aluminium surfaces to produce a highly reflective, glossy finish. Common in architectural and decorative applications, this process enhances the aesthetic appeal of aluminium components.
• BRSR: Business Responsibility and Sustainability Report is a mandatory ESG disclosure framework introduced by SEBI in India, requiring companies, including aluminium producers, to report on their environmental, social and governance performance. The BRSR promotes transparency and helps stakeholders evaluate a company’s sustainability strategy and impact.
• Brushing: Brushing is a surface finishing process where aluminium is mechanically abraded with fine brushes to produce a uniform, satin texture. It improves surface aesthetics and prepares the metal for anodising or coating.
• Buffing: Buffing is a polishing technique that smoothens and enhances the shine of aluminium surfaces using rotating cloth wheels and abrasive compounds. It is commonly used for decorative parts requiring a high-gloss finish.
• Burr: A burr is a small, unwanted projection of metal that forms on aluminium edges during cutting, machining, or punching operations. Burrs are typically removed by deburring processes to improve safety, aesthetics and assembly quality.

C

• Canstock: Canstock refers to flat-rolled aluminium sheets specifically manufactured for producing beverage cans and food containers, known for their strength, formability, and recyclability.
• Carbon Accounting: Carbon accounting is the process of measuring and tracking greenhouse gas (GHG) emissions produced directly or indirectly by an organisation, product, or activity. In the aluminium industry, carbon accounting helps quantify emissions from mining, smelting, processing and transportation, enabling companies to set reduction targets, comply with regulations and report progress toward sustainability goals.
• Carbon Credit: A carbon credit is a tradable permit that allows an entity to emit a certain amount of carbon dioxide or other greenhouse gases, used to incentivize emission reductions and support environmental sustainability.
• Carbon Disclosure: Carbon disclosure is the process by which companies report their greenhouse gas emissions, climate-related risks, and mitigation strategies, promoting transparency and accountability in environmental performance.
• Carbon Footprint: A carbon footprint is the total amount of greenhouse gases emitted directly or indirectly by an individual, organization, product, or activity, typically measured in equivalent tons of carbon dioxide.
• Carbon Market: The carbon market is a trading system where companies buy and sell carbon credits to offset greenhouse gas emissions. In the aluminium industry, participation in carbon markets supports decarbonisation goals and incentivises the shift to low-carbon production processes.
• Carbon Neutral: Carbon neutral refers to achieving a net-zero carbon footprint by balancing emitted greenhouse gases with equivalent offsets or removal measures, often through renewable energy and sustainability initiatives.
• Carbon Offset: A carbon offset is a reduction in greenhouse gas emissions, such as through reforestation or renewable energy projects, used to compensate for emissions produced elsewhere and help achieve climate goals.
• Carbon Pricing: Carbon pricing is a market-based approach to reducing greenhouse gas emissions by assigning a monetary cost to emitting carbon dioxide, encouraging emitters to lower their carbon output through financial incentives.
• Carbon Sequestration: Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide, typically through natural methods like afforestation or technological solutions, to mitigate the impact of climate change.
• Carbon Tax: A carbon tax is a direct tax imposed on the carbon content of fossil fuels, aimed at discouraging greenhouse gas emissions by making carbon-intensive activities more expensive.
• Carbon Trade: Carbon trade, also known as emissions trading, is a system where companies can buy or sell emission allowances under a regulated cap, enabling cost-effective compliance with emission reduction targets.
• Casting: Casting is a manufacturing process where molten aluminium is poured into a mould to form specific shapes, commonly used in the production of automotive parts, tools and industrial components.
• Caustic: In the aluminium industry, caustic refers to caustic soda (sodium hydroxide) used in chemical treatments like etching and cleaning. It helps remove oxides and prepare aluminium surfaces for anodising or other finishes.
• CBAM: Carbon Border Adjustment Mechanism is a regulatory tool proposed by the European Union to place a carbon price on imports of certain goods, ensuring that imported products meet the same carbon reduction standards as those produced within the EU.
• Chatter: Chatter is a machining defect where periodic marks or vibrations occur on aluminium surfaces due to tool instability. Minimising chatter is essential in precision manufacturing to ensure smooth finishes and dimensional accuracy.
• Chatter Mark: Chatter marks are repetitive surface patterns or grooves caused by vibrations during the machining of aluminium. These marks can compromise surface aesthetics and require corrective finishing in critical applications.
• Chemical Brightening: Chemical brightening is a pre-anodising treatment where aluminium is immersed in an acid solution to smooth the surface and increase its reflectivity. It prepares the metal for bright anodised finishes.
• Chemical Polishing: Chemical polishing involves immersing aluminium in a chemical solution to smooth and level the surface by dissolving microscopic peaks. It enhances reflectivity and is often used before anodising.
• Circular Economy: A circular economy is an economic model focused on minimizing waste and maximizing resource efficiency by reusing, recycling, and repurposing materials like aluminium across product life cycles.
• Cladding: Cladding refers to the application of one material over another to provide a protective or aesthetic layer, with aluminium cladding often used in building facades for its durability, lightweight nature and corrosion resistance.
• Clean Energy: Clean energy refers to energy derived from renewable, low-emission sources such as solar, wind, hydro, and geothermal, which produce little to no greenhouse gas emissions and contribute to a sustainable energy future.
• Clear Anodised Aluminium: Clear anodised aluminium has a transparent oxide layer formed through anodising without added dyes. It retains the metal’s natural appearance while offering improved durability and corrosion resistance.
• Cold Sealing: Cold sealing is a post-anodising process where aluminium is sealed at room temperature using chemical solutions. It closes the anodic pores to enhance corrosion resistance and preserve surface finish.
• Colour Anodised Aluminium: Colour anodised aluminium is aluminium that has undergone an electrochemical process to form a durable oxide layer, which is then dyed in various colours for decorative and corrosion-resistant applications in architecture, consumer goods and electronics.

D

• Decarbonisation: Decarbonisation refers to the process of reducing carbon dioxide emissions across sectors such as energy, transportation and industry, often by shifting to renewable energy sources and improving energy efficiency to combat climate change.
• Die: A die in aluminium processing is a precision tool used in extrusion and forging to shape aluminium into specific profiles or components. High-quality dies are essential for consistent production and dimensional accuracy in aluminium manufacturing.
• Die Holder: A die holder is a mechanical component that securely holds the die in place during extrusion or forming processes. It ensures stability, alignment and proper function of the die for efficient aluminium profile production.
• Die Ring: A die ring is a structural support ring that helps maintain the positioning and pressure of the die within the die holder during aluminium extrusion. It plays a crucial role in maintaining shape accuracy and extending die life.
• Dismantlers: Dismantlers are facilities or professionals responsible for systematically taking apart end-of-life vehicles, machinery, or products to recover recyclable materials like aluminium, ensuring sustainable reuse and reducing landfill waste.
• Downstream Products: Downstream products are finished or semi-finished goods made from processed aluminium, such as sheets, foils, extrusions and castings, used in industries like automotive, packaging, construction and electronics.
• Dross: Dross is a byproduct formed during the melting and refining of aluminium, consisting of oxidised impurities and metal oxides. Efficient dross management and recycling are essential in aluminium production to reduce waste and recover valuable metal content.
• Ductility: Ductility refers to aluminium’s ability to deform under tensile stress without breaking, allowing it to be drawn into wires or stretched into thin sheets. This property is critical for forming, bending and fabrication processes in the aluminium industry.
• Dummy Block: A dummy block is a part of the aluminium extrusion press that acts as a barrier between the billet and the ram. It ensures smooth extrusion flow and protects the press components from direct contact with molten aluminium.
• Dyed Anodised Aluminium: Dyed anodised aluminium is anodised aluminium that has been treated with pigments or dyes to achieve specific colours, combining enhanced aesthetic appeal with improved corrosion and wear resistance for architectural and design uses.

E

• Eccentricity: Eccentricity in aluminium manufacturing refers to the deviation of a product’s cross-sectional shape or wall thickness from its intended centre. Minimising eccentricity is important for ensuring structural integrity and performance consistency.
• Electrical Conductivity: Electrical conductivity is a measure of aluminium’s ability to conduct electric current. Due to its high conductivity and lightweight nature, aluminium is widely used in power transmission lines, electrical wiring and electronic components.
• Extrusion: Extrusion is a manufacturing process where aluminium billets are forced through a shaped die to create long products with consistent cross-sections, commonly used in window frames, automotive parts and construction profiles.
• Extrusion Butt: An extrusion butt is the remaining portion of an aluminium billet that cannot be extruded through the die. It is removed at the end of the extrusion cycle to maintain product quality and protect the extrusion die from damage.
• Extrusion Die: An extrusion die is a precision-engineered tool made of high-strength steel, used to shape aluminium billets into desired profiles during the extrusion process. The die defines the final cross-sectional shape of the extruded product.
• Extrusion Press: An extrusion press is a hydraulic or mechanical machine that forces aluminium billets through a die under high pressure to produce continuous profiles with uniform cross-sections, widely used in construction, transportation and packaging industries.
• Extrusion Press Solution Heat Treatment: Extrusion press solution heat treatment is a process where aluminium extrusions are rapidly cooled and then heated to a specific temperature to dissolve soluble elements. This enhances mechanical properties and prepares the metal for aging or tempering.
• Extrusion Ratio: The extrusion ratio is the ratio between the cross-sectional area of the aluminium billet and the area of the extruded profile. It indicates the degree of deformation and affects the strength, grain structure and surface finish of the final product.
• Extrusion Seam: An extrusion seam is a visible line or boundary formed when separate metal flows rejoin during the extrusion process. While typically minor, seams can impact surface appearance and mechanical properties, depending on extrusion design and parameters.

F

• Fabrication: Fabrication involves cutting, bending, joining, and assembling aluminium components into final structures or products, playing a critical role in sectors like aerospace, automotive and industrial manufacturing.
• Feeder Plate: A feeder plate is a component used in aluminium extrusion dies to control metal flow and ensure uniform distribution across the profile. It plays a critical role in achieving dimensional accuracy and minimising defects.
• Fillet: A fillet in aluminium design refers to the rounded internal corner between two surfaces or sections. It reduces stress concentration, improves load distribution and enhances the structural integrity of extruded or fabricated components.
• Finish: Finish refers to the surface quality or appearance of aluminium products after extrusion or fabrication. It can include mill finish, anodising, powder coating, or mechanical treatments and influences aesthetics, corrosion resistance and application suitability.
• Flatness: Flatness measures the deviation of an aluminium sheet or plate from a perfectly flat surface. Ensuring flatness is critical in applications like automotive panels, aerospace parts and architectural components, where precision and surface uniformity matter.
• Forging: Forging is a forming process that shapes aluminium under high pressure, enhancing its strength and durability, and is widely used in producing high-performance parts for aerospace, automotive and defence applications.
• Furnace Solution Heat Treatment: Furnace solution heat treatment in the aluminium industry involves heating aluminium alloys to a specific temperature to dissolve alloying elements into a solid solution, followed by rapid quenching. This process enhances strength, ductility, and corrosion resistance in aerospace, automotive and structural applications.

G

• Green aluminium: Green aluminium refers to aluminium produced using low-carbon or renewable energy sources, significantly reducing its carbon footprint and supporting global efforts toward sustainable and climate-friendly manufacturing.
• Green Technology: Green technology in the aluminium sector includes innovations and processes that minimize environmental impact. These include energy-efficient smelting, waste heat recovery, low-carbon materials and recycling systems that reduce carbon emissions and conserve resources.
• Greenhouse Gases: Greenhouse gases are atmospheric gases, such as carbon dioxide, methane and nitrous oxide, that trap heat from the sun, contributing to global warming and climate change.

H

• Hall Herolt: The Hall Herolt process is the primary method of extracting aluminium from alumina by dissolving it in molten cryolite and electrolysing it, consuming large amounts of electricity and producing pure aluminium.
• Hard Anodised Aluminium: Hard anodised aluminium refers to aluminium that has undergone an electrochemical process to form a thick, hard and wear-resistant oxide layer. Common in cookware, automotive, and industrial components, it improves durability, corrosion resistance and surface hardness.
• Hardening: Hardening in the aluminium industry refers to heat treatment or alloying processes that increase the metal’s strength and mechanical properties. Techniques like precipitation hardening are used in high-performance applications such as aerospace and automotive manufacturing.
• Heat Treatment: Heat treatment is a controlled process of heating and cooling aluminium alloys to alter their physical and mechanical properties, enhancing strength, ductility and resistance to wear or corrosion.
• Hot Tears: Hot tears are cracks or fractures that occur during the solidification of aluminium castings due to thermal stress and restricted contraction. They are a key casting defect that manufacturers seek to minimize through alloy design, mold configuration and controlled cooling.

I

• Ingot: An ingot is a large, solid block of aluminium cast into a specific shape for further processing, serving as a raw material for rolling, extrusion, or remelting operations.

L

• Lifecycle assessment: Lifecycle assessment (LCA) is a systematic evaluation of the environmental impact of a product throughout its entire life, from raw material extraction and production to usage and end-of-life disposal or recycling.
• Longitudinal Extrusion Seam: A longitudinal extrusion seam is a visible line or weak point along the length of an extruded aluminium product, resulting from incomplete fusion of metal streams. Controlling die design and extrusion parameters helps minimize seams in architectural and industrial profiles.

M

• Matte Finish: Matte finish in aluminium refers to a non-reflective, smooth surface texture achieved through mechanical brushing, chemical etching, or anodizing. It is widely used in architectural and decorative applications for its modern appearance and reduced glare.
• Mechanical Polishing: Mechanical polishing in aluminium processing involves using abrasives or buffing techniques to smooth and shine the metal surface. This enhances visual appeal, reduces surface defects, and prepares the metal for further treatments like anodizing or coating.
• Mill Finish: Mill finish aluminium refers to the natural, unfinished surface condition of aluminium directly after extrusion or rolling. While functional, it may have surface imperfections and is typically used in industrial applications or further processed for decorative uses.
• Mirror Finish: Mirror finish aluminium is a highly reflective surface achieved through precision polishing or buffing. Used in lighting, signage, and decorative applications, it enhances aesthetic appeal and requires high-grade alloys and finishing processes.

N

• Natural Oxide Film: The natural oxide film on aluminium is a thin, protective layer of aluminium oxide that forms spontaneously when exposed to air. This layer provides corrosion resistance and serves as a base for anodising or coating in various aluminium products.
• Net Zero: Net Zero refers to the balance between the amount of greenhouse gases emitted and the amount removed from the atmosphere. In the aluminium industry, achieving Net Zero means reducing emissions from mining, smelting and processing, while offsetting any remaining carbon through renewable energy, carbon capture, or reforestation efforts.

O

• Ovality: Ovality refers to the deviation of an aluminium tube or extrusion from a perfect circular cross-section, often measured as the difference between maximum and minimum diameters. Controlling ovality ensures precision in manufacturing and quality in end-use applications like aerospace and automotive.

P

• Polished Aluminum: Polished aluminum is aluminium that has undergone surface finishing to achieve a smooth, reflective and aesthetically appealing surface. It is widely used in architectural designs, consumer goods and decorative applications due to its corrosion resistance and modern look.
• Porthole Die: A porthole die is a type of extrusion die used in aluminium manufacturing to produce hollow profiles. It employs bridges and mandrels to shape aluminium into complex hollow sections for construction, transportation and industrial uses.
• Powder Coating: Powder coating is a dry finishing process where electrostatically charged powder particles are applied to aluminium surfaces and cured under heat, resulting in a durable, high-quality finish with enhanced corrosion resistance.
• Primary Aluminium: Primary aluminium is aluminium produced directly from bauxite ore through refining and electrolysis, as opposed to secondary aluminium derived from recycled scrap.
• Profile: A profile in the aluminium industry refers to a specific cross-sectional shape produced by extrusion. Aluminium profiles are used across sectors such as construction, transportation and electronics for their lightweight, durable and customisable properties.

R

• Ram: A ram is a hydraulic or mechanical component in an aluminium extrusion press that applies pressure to force heated aluminium billets through a die, creating profiles of desired shapes and dimensions.
• Recycling: Recycling in the aluminium industry refers to the process of collecting and reprocessing used aluminium products into new materials, conserving energy and reducing the need for primary metal production.
• Red Mud: Red mud is a highly alkaline industrial waste generated during the Bayer process of refining bauxite into alumina. It poses environmental challenges but is being researched for reuse in construction and other industries.
• Refinery: A refinery in the aluminium industry is a facility where bauxite is processed into alumina using the Bayer process, serving as a crucial step in the production of primary aluminium.
• Refining: Refining is the industrial process of purifying raw bauxite to extract alumina (aluminium oxide), typically through the Bayer Process, which is a key step in the aluminium production chain before smelting.
• Remelt: Remelt refers to the process of melting down scrap or previously used aluminium to produce reusable metal, supporting sustainability and reducing energy consumption compared to primary aluminium production.
• Renewable Energy: Renewable energy refers to power generated from natural sources like solar, wind, hydro, or geothermal. In the aluminium industry, using renewable energy significantly lowers carbon emissions during smelting and processing.
• Rolling: Rolling is a mechanical process where aluminium is passed through rollers to reduce its thickness and convert it into sheets, foils, or plates, commonly used in packaging, construction and automotive industries.
• Run-out Table: A run-out table is a cooling and handling system in aluminium extrusion lines where freshly extruded profiles are guided, supported and cooled after exiting the die to maintain straightness and prevent distortion.

S

• Salt Slag: Salt slag is a by-product of aluminium recycling, composed of salt fluxes, metal oxides and other residues. It is processed further to recover valuable materials and reduce environmental impact.
• Scrap: Scrap refers to discarded or leftover aluminium that can be collected and recycled. Utilising aluminium scrap helps lower production costs and environmental footprint, as it requires just 5% of the energy used in primary production.
• Sealing: Sealing in aluminium refers to the final stage of anodising, where the porous oxide layer is closed to enhance corrosion resistance and improve durability. It protects aluminium components in architectural and marine environments.
• Shear Strength: Shear strength is the maximum stress aluminium can withstand before failure in response to forces that cause layers to slide against each other. It is critical in evaluating aluminium’s structural performance in aerospace, automotive and construction applications.
• Shot Blasting: Shot blasting is a surface treatment process where high-speed abrasive particles clean, strengthen, or polish aluminium surfaces. It improves adhesion for coatings and is essential for preparing aluminium for finishing processes.
• Shredder: A shredder is a machine used in aluminium recycling to break down large aluminium parts or scrap into smaller, manageable pieces for easier sorting, cleaning and remelting.
• Shrinkage: Shrinkage in aluminium casting refers to the reduction in volume as molten aluminium solidifies and cools. Managing shrinkage is vital to prevent defects like cavities or cracks in finished components.
• Slab: A slab is a semi-finished aluminium product formed through casting or rolling processes. It serves as an intermediate material, later rolled into sheets or plates for industrial applications.
• Smelter: A smelter is an industrial facility where alumina is reduced to pure aluminium using electrolysis, typically through the Hall-Héroult process. Smelters are energy-intensive and increasingly powered by renewable energy sources to lower emissions.
• Solar Powered – Smelting: Solar powered smelting refers to the use of solar energy to power the electrolysis process in aluminium production. This sustainable approach reduces the industry’s dependence on fossil fuels and helps achieve low-carbon aluminium output.
• Sorting: Sorting is a key step in aluminium recycling where scrap is separated based on alloy type, size, or purity. Efficient sorting improves material recovery, reduces contamination and ensures high-quality output for remelting and reuse in manufacturing.
• Stamping: Stamping is a precision forming process used in aluminium fabrication to cut or shape metal using a press and die. Commonly used in automotive and electronics industries, aluminium stamping enables mass production of lightweight, durable components with high dimensional accuracy.

W

• Wire Rod: An aluminium wire rod is a long, coiled semi-finished product produced by rolling aluminium billets. It is primarily used in electrical transmission, welding, and cabling due to aluminium’s high conductivity, corrosion resistance and lightweight nature.