Aluminium Profiles in the Sign Industry: Technical Guide

What Are Aluminium Profiles?

Aluminium profiles (also referred to as aluminium extrusions or sections) are continuous lengths of aluminium alloy produced by forcing heated aluminium billets through a precision-machined steel die. The resulting cross-section can be simple (angles, flats, channels) or highly complex (snap-fit lightboxes, SEG frames, raceways, and multi-cavity structural members).

Unlike fabricated steel sections, aluminium profiles are formed in a single operation, allowing geometry, fixing features, drainage, LED mounting, and stiffness to be engineered directly into the profile.

Material Science: What Aluminium Profiles Are Made Of

Aluminium Alloys

Almost all sign industry aluminium profiles are manufactured from 6000-series aluminium alloys (Al–Mg–Si). These alloys are specifically chosen because they offer:

Excellent extrudability
Good surface finish
Heat-treatable strength
Strong corrosion resistance
Compatibility with anodising and powder coating

However, 5000-series and 7000-series alloys also appear in niche or specialist sign-industry applications and are important to understand from a specification and performance perspective.

5000 Series Alloys (Aluminium–Magnesium)

5000-series alloys are non-heat treatable and derive their strength from magnesium content and cold working rather than ageing. They are not commonly extruded into complex sign profiles but are highly relevant in sheet, plate, and folded sign construction.

Common 5000 Series Alloys Relevant to Signage

Alloy	Typical Form	Yield Strength (MPa)	Key Characteristics
5005	Sheet / Coil	~125 MPa	Excellent anodising quality, good formability
5052	Sheet / Plate	~193 MPa	Very good corrosion resistance, strong fatigue performance
5083	Plate	~215 MPa	Marine-grade corrosion resistance, high strength

Where 5000 Series Is Used in the Sign Industry

Folded aluminium trays
Sign faces and returns
Marine or coastal signage
High-corrosion environments
Laser-cut lettering back panels

Limitation: Cannot be strengthened by heat treatment.

7000 Series Alloys (Aluminium–Zinc)

7000-series alloys are high-strength, aerospace-grade materials. They are rarely used in mainstream signage but may appear in critical load-bearing or specialist structural components.

Common 7000 Series Alloys

Alloy	Typical Use	Yield Strength (MPa)	Notes
7075	Structural / Mechanical	~500+ MPa	Extremely high strength, poor corrosion resistance
7020	Structural Extrusions	~300–350 MPa	Better corrosion resistance than 7075

Potential Sign Industry Applications

Extreme wind-load structures
Long-span cantilevered signs
Temporary or modular event structures
Lightweight structural frames where steel weight is prohibitive

Constraints of 7000 Series in Signage

Poor corrosion resistance (requires protection)
Difficult and expensive to extrude
Poor surface finish for architectural use

Mechanical Properties & Alloy Composition Overview

While chemical composition determines how an alloy behaves metallurgically, it is the resulting mechanical properties — yield strength, tensile strength, and elongation — that determine suitability for specific signage applications. The table below summarises the most relevant alloys used in the sign industry, combining typical composition ranges with key structural performance values.

Values shown are typical ranges for common tempers (primarily T6 for 6000/7000 series and H32/H111 for 5000 series). Actual properties vary slightly depending on supplier and production route.

Alloy	Primary Alloying Elements (% Typical)	Temper	Yield Strength (MPa)	Tensile Strength (MPa)	Elongation (%)	Sign Industry Relevance
6063	Mg: 0.45–0.9 Si: 0.2–0.6	T6	~170	~205–215	8–12	Industry standard for architectural profiles, lightboxes, trims
6005A	Mg: 0.4–0.7 Si: 0.5–0.9	T6	~225	~260–270	6–10	Heavier-duty frames, posts, structural sign systems
6082	Mg: 0.6–1.2 Si: 0.7–1.3 Mn: up to 1.0	T6	~260–280	~300–320	6–8	High-load structural components, reduced fine-detail capability
5005	Mg: 0.5–1.1	H32	~125	~145–185	12–18	Folded trays, anodised sign faces
5052	Mg: 2.2–2.8	H32	~190–200	~230–260	10–15	Fabricated trays, marine/coastal signage
5083	Mg: 4.0–4.9	H111	~215	~300–320	10–16	High-corrosion, high-strength sheet applications
7020	Zn: 4.0–5.0 Mg: 1.0–1.4	T6	~300–350	~350–400	8–10	Specialist structural extrusions
7075	Zn: 5.1–6.1 Mg: 2.1–2.9 Cu: 1.2–2.0	T6	~500–540	~560–600	5–8	Extreme strength, niche load-critical applications

Temper Designation

In aluminium specification, temper designation is just as critical as alloy selection. Temper defines the mechanical properties achieved through heat treatment and ageing.

In the sign industry, the most relevant tempers are T4 and T6, particularly within the 6000-series alloys.

T4 Temper (Solution Heat Treated & Naturally Aged)

T4 aluminium has been:

Solution heat treated
Quenched
Allowed to naturally age at room temperature

Key Characteristics of T4

Lower strength than T6
Significantly higher ductility and formability
Softer material condition
Easier to bend, fold, roll, and machine

Typical Mechanical Properties (6063-T4)

Yield Strength: ~80–110 MPa
Elongation: High

Where T4 Is Used in the Sign Industry

Profiles requiring post-extrusion forming
Curved or radius lightboxes
Fabricated returns where cracking risk must be minimised
Custom architectural features formed after extrusion

Important Practical Notes

T4 material will continue to age over time
Strength increases gradually but never reaches T6 levels without artificial ageing
Poor choice for final structural performance unless re-aged

T6 Temper

Typical Mechanical Properties (6063-T6)

Yield Strength: ~170 MPa
Tensile Strength: ~215 MPa

Where T6 Is Used in the Sign Industry

Structural sign frames
Posts, totems, and monoliths
Long-span fascias
Modular signage systems
Any application subject to wind loading

Practical Considerations

Harder to bend or form without cracking
Any welding or heavy forming locally reduces strength
Heat-affected zones revert to near-T4 condition unless re-aged

T4 vs T6 – Direct Comparison

Property	T4	T6
Strength	Low–Medium	High
Formability	Excellent	Limited
Stability	Ages over time	Stable
Typical Use	Forming before final ageing	Final installed condition
Sign Industry Role	Manufacturing stage	Installed performance

How the Brinell Hardness Test Works

A hardened steel or tungsten carbide ball (typically 10 mm diameter) is pressed into the material surface
A known force is applied for a fixed time
The diameter of the indentation is measured
Hardness is calculated based on load and indentation size

For aluminium alloys, hardness values are typically reported as HBW.

Typical Brinell Hardness Values for Sign Industry Alloys

Alloy & Temper	Brinell Hardness (HBW)	Practical Interpretation
6063-T4	~60–70 HB	Soft, lightly formable, easily scratched
6063-T6	~70–80 HB	Good balance of strength and surface durability
6005A-T6	~80–90 HB	More dent-resistant, suitable for posts & frames
6082-T6	~90–100 HB	High resistance to deformation
5005-H14	~45–55 HB	Very soft, prone to marking
5052-H32	~60–65 HB	Tougher sheet material
7075-T6	~150 HB	Extremely hard, overkill for most signage

Strength Properties Relevant to Signage Design

Understanding tensile, shear, and fatigue strength is essential when aluminium profiles are exposed to wind loading, vibration, cyclic stress, and mechanical fixing.

Typical Tensile Properties (6000 Series)

Alloy & Temper	Yield Strength (MPa)	Ultimate Tensile Strength (MPa)
6063-T4	~90	~150
6063-T6	~170	~215
6005A-T6	~225	~260
6082-T6	~260	~310

Practical Insight: In signage, deflection limits are often reached long before tensile failure — profile geometry is as important as alloy choice.

Shear Strength

Shear strength describes resistance to forces acting parallel to a cross-section.

In signage this relates to:

Fixings and fasteners
Riveted and bolted joints
Clamped sign rails
Anchor points to building fabric

For aluminium alloys, shear strength is typically 55–65% of ultimate tensile strength.

Approximate Shear Strength Values

Alloy & Temper	Approx. Shear Strength (MPa)
6063-T6	~120–140
6005A-T6	~150–165
6082-T6	~180–200

Common failure mode: Fixing pull-out or bolt shear occurs more often than profile rupture.

Fatigue Performance (Indicative)

6063-T6 fatigue strength at 10⁷ cycles: ~50–70 MPa
6082-T6 fatigue strength at 10⁷ cycles: ~80–100 MPa

High-Risk Fatigue Areas

Welded joints (heat-affected zones)
Sharp internal corners
Poorly isolated fixings
Long unsupported spans

Best Practice for Managing Fatigue in Sign Structures

Avoid sharp corners and stress raisers
Use generous radii in profile design
Minimise welding where possible
Design for stiffness, not just strength
Follow Eurocode 9 fatigue guidance

Why Brinell Hardness Matters in the Sign Industry

Fabrication & Handling

Softer alloys mark easily
Harder alloys resist roller marks, clamp damage, dents

Surface Finish Performance

Low hardness heavily impacts powder coating durability
Higher hardness improves resistance beneath coatings

Installation & Service Life

Totems, posts, exposed profiles benefit from higher hardness
Internal display systems can tolerate lower hardness

Limitations of Using Hardness Alone

Hardness does not directly equal load-bearing capacity
Does not account for profile geometry or wall thickness
Wind loading and deflection must be calculated separately
Coatings significantly affect scratch resistance

Summary of Alloy Selection by Series

Series	Typical Use in Signage	Suitability
5000	Sheet, trays, folded signs	Excellent for fabrication, not profiles
6000	Extruded profiles & systems	Industry standard
7000	Specialist structural	Rare / niche use only

Key Material Properties (General Aluminium)

Density: ~2.7 g/cm³ (approx. one-third of steel)
Elastic Modulus: ~69 GPa
Thermal Conductivity: High (beneficial for LED heat dissipation)
Corrosion Resistance: Natural oxide layer protects against atmospheric exposure
Recyclability: 100% recyclable with no degradation

Manufacturing Process (Extrusion Lifecycle)

Billet Casting & Preparation
Billet Heating (~450–500°C)
Extrusion through precision die
Quenching
Stretching
Cutting & Ageing
Surface Finishing

Surface Finishes & Treatments

Mill Finish (Raw)

As-extruded surface
Economical
May show die lines
Typically used for concealed structural components

Powder Coating (Most Common)

Electrostatic polyester powder
Oven cured
Available in RAL, BS, metallic, textured finishes
Excellent UV, corrosion, and impact resistance
Industry standard for external signage

Anodising

Electrochemical oxidation
Finish becomes integral to the metal
Superior corrosion resistance
Metallic architectural appearance

Decorative / Sublimated Finishes

Wood-effect and specialist films
UV stable
Common in retail, hospitality, heritage

Problems Aluminium Profiles Solve

Weight reduction vs steel
Corrosion resistance outdoors
Integrated functionality (LED mounting, drainage, snap-fit faces)
Consistent accuracy
Modularity
Improved sustainability

Use Cases (By Sign Type)

Illuminated Signage

Integrated LED channels
Heat dissipation
Precise face retention

Large-Format Fascias

Lightweight load
Expansion-tolerant joints
Concealed fixings

Modular Sign Systems

Repeatable profiles
Easy face changes
Reduced installation time

Coating Standards

BS EN 12206 – Powder coating of aluminium
Qualicoat – Powder coating quality assurance
Qualanod – Anodising quality standards

Structural & Installation Standards

Eurocode 9 (EN 1999) – Design of aluminium structures
BS 8102 / BS EN 1090 (contextual use)

Aluminium Constraints & Limitations

Lower stiffness than steel
Higher material cost
Thermal expansion must be accommodated
Poor galvanic compatibility with some metals
Limited fatigue resistance vs steel

Common Buyer & Fabricator Mistakes

Selecting 6063 where structural strength is required
Ignoring wind load calculations
Poor thermal expansion allowance
Mixing dissimilar metals
Over-specifying finishes unnecessarily
Assuming all aluminium profiles are interchangeable

Buyer Choices & Specification Considerations

Alloy and temper selection
Wall thickness
Profile geometry
Finish type and coating thickness
Length tolerances
Load-bearing requirements
Installation method

Example Specification Table

Parameter	Typical Range
Alloy	6063-T6 / 6005A-T6
Wall Thickness	1.2–4.0 mm
Length	Up to 6.5 m standard
Finish	Mill / Powder / Anodised
Coating Thickness	60–120 microns (powder)
Corrosion Class	C2–C4 (with coating)

Regulatory & Industry Bodies

BSI (British Standards Institution)
Qualicoat UK & Ireland
Qualanod
Aluminium Federation (ALFED)
European Aluminium Association
SGIA (reference only)

Specifier-Grade Structural Design Guidance for Aluminium Signage

Wind Loading for Sign Designers (Eurocode-Aligned)

Applicable standards:

BS EN 1991-1-4 (Eurocode 1) – Wind actions
UK National Annex

Key Concepts

Basic wind velocity (vb)
Exposure category
Height factor
Shape coefficient (flat signs generate higher pressure)

Practical Implications

Large flat fascias behave as sails
Totems experience combined bending & torsion
Edge zones experience higher local pressures

Rule of thumb: Aluminium profiles are usually governed by deflection and fixing capacity before material strength is exceeded.

Deflection Limits

Structural adequacy is not solely about preventing collapse.

Most aluminium signs fail the serviceability check long before approaching material failure.

Fixing Failure Modes

Aluminium profiles rarely fracture. Failure usually occurs at fixings.

Primary failure modes:

Pull-out
Shear failure
Bearing failure
Tear-out

Always design fixings as a system: profile + fastener + substrate.

Heat-Affected Zone (HAZ) Strength Reduction After Welding

Welding locally destroys T6 temper.

Effects:

Artificial ageing reversed
Material reverts to near-T4 condition

Best practice:

Oversize welded sections
Assume reduced properties unless re-aged

Fatigue Design & Cyclic Loading (Eurocode 9 Context)

Aluminium has no endurance limit.

Design must consider:

Wind-induced vibration
Traffic oscillation
Thermal cycling

Design for stiffness and smooth load paths — not just strength.

Structural Hierarchy of Good Aluminium Sign Design

Profile geometry & stiffness
Fixing design & substrate capacity
Deflection control
Fatigue resistance
Material strength
Hardness

Real-world performance reflects this hierarchy.

Summary

Aluminium profiles are not merely a construction material but a fully engineered system solution for the sign industry. Their versatility, precision, durability, and sustainability make them irreplaceable in modern signage.

Correct alloy selection, profile design, finishing, and specification are critical to performance, longevity, and compliance.

A deep understanding of aluminium profiles allows sign professionals to design safer, longer-lasting, and more cost-effective signage systems while meeting regulatory and aesthetic demands.