By the end of this topic, you should be able to...
explain how and why materials are classified and discuss the advantages of classifying materials in terms of physical, chemical and mechanical properties.
Guiding Question
How do material properties and classifications aid material selection for a specified manufacturing process?
💡 Did You Know? Every object you've touched today—your phone, your chair, the bottle on your desk—exists because a designer made a critical decision: which material should this be made from?
Why Study Material Properties?
Material selection isn't guesswork. When Apple engineers chose aerospace-grade aluminum for the iPhone chassis, they weren't just picking "metal"—they were analyzing tensile strength, thermal conductivity, machinability, corrosion resistance, and recyclability. Get it right, and you create a product that's lightweight, durable, and elegant.
Get it wrong, and you risk catastrophic failure. Understanding how materials are classified by their physical (density, melting point), chemical (reactivity, degradation), and mechanical (strength, elasticity, hardness) properties gives designers a structured framework to compare options, predict performance, and justify choices with evidence—not intuition.
Case in Point
Apple's iPhone 15 Pro uses titanium Grade 5 alloy for its frame—chosen through rigorous classification analysis. Compared to previous aluminum (6061-T6), titanium offers superior mechanical strength-to-weight ratio (30% stronger, equally light), better chemical corrosion resistance (survives saltwater exposure), and desirable physical thermal properties (doesn't feel ice-cold in winter). This single material substitution, enabled by systematic property classification, allowed Apple to reduce device thickness by 0.8mm while improving drop durability—a $2 billion R&D decision justified entirely through material science data.
Learning Goals
In this topic, you'll learn the logic behind material classification systems, explore how physical, chemical, and mechanical properties shape design decisions, and develop the analytical skills to select—and defend—material choices in your own Internal Assessment project.
Linking Questions
Why is a good understanding of material properties important when designing structural systems? (A3.2)
When do the physical properties of materials restrict the ability to use certain prototyping techniques? (A2.2)
How do the properties of a material influence the choice of manufacturing techniques for a product? (A4.1)
How can the characteristics of a material limit the effectiveness of modelling and prototyping as designs are developed? (B2.2)
How important is an understanding of the mechanical properties of a material when considering structural and mechanical systems, and their applications? (A3.2, A3.3, B3.2, B3.3)
Which classifications of properties are important when developing electronic systems and their applications? (A3.4, B3.4)
How could the continued development of biodegradable materials influence designers’ ability to address aspects of design for sustainability and design for a circular economy? (C2.1, C2.2)
Why is a thorough understanding of materials key for effective product analysis and evaluation of products? (C3.1)
How do design decisions related to the properties of materials and components impact a product’s life-cycle analysis? (C3.2)