Welcome to Core Materials: Metals, Papers, and Boards!

Ever wondered why your fizzy drink comes in an aluminium can rather than a steel one? Or why a cereal box is made of one type of card while a shipping box is another? In this chapter, we are going to look at the "Core" materials you need to know for your exam. These are the building blocks of almost everything we design.

Don't worry if this seems like a lot to remember—we’ll break it down into simple categories and look at the working properties that make each material special.

1. Metals (Core Topic 1.8)

Metals are divided into two main groups: Ferrous and Non-ferrous. The easiest way to remember the difference? "Ferrum" is the Latin word for iron. If it's Ferrous, it contains iron!

Ferrous Metals (They contain iron)

Most ferrous metals are magnetic and will rust if exposed to moisture and oxygen.

  • Mild Steel: This is the most common metal. It is ductile and malleable. It’s used for things like car bodies and nuts and bolts because it's strong and relatively cheap.
  • Stainless Steel: An alloy of steel that contains chromium. This makes it resistant to rust (corrosion). It is used for cutlery, kitchen sinks, and medical instruments.
  • Cast Iron: Very hard but also brittle (it can snap if hit hard). It is excellent for things that need to withstand heavy pressure, like manhole covers or engine blocks.

Non-Ferrous Metals (No iron here!)

These do not contain iron, which means they are generally not magnetic and do not rust (though they can still tarnish or corrode in other ways).

  • Aluminium: Lightweight, malleable, and resists corrosion. It's a great conductor of heat. Application: Drink cans, foil, and aircraft parts.
  • Copper: A reddish-brown metal that is an excellent conductor of electricity and heat. It is very ductile. Application: Electrical wiring and plumbing pipes.
  • Brass: A mixture (alloy) of copper and zinc. It is hard and resists corrosion well. Application: Musical instruments (like trumpets) and door handles.

Key Metal Properties to Know

The exam will ask you about these three specific properties:

  1. Ductility: The ability of a material to be stretched into a thin wire without snapping. (Think of copper being pulled into long electrical wires).
  2. Malleability: The ability to be hammered or pressed into shapes/sheets without cracking. (Think of an aluminium drink can).
  3. Hardness: The ability to resist scratching, wear, and tear, or indentation. (Think of a cast iron manhole cover resisting the weight of a truck).
Quick Tip: Memory Aid!

Malleable = Mashable (you can hammer it).
Ductile = Draw-able (you can pull it into a wire).

2. Papers and Boards (Core Topic 1.9)

We often think of paper as just "paper," but designers choose specific types based on how they look, how they feel, and what they need to do.

Types of Paper

  • Copier Paper: The standard white paper you use in a printer. It is smooth and lightweight.
  • Cartridge Paper: Thicker and has a slightly textured surface. It’s better for drawing with pencils or inks because it doesn't "bleed" as much.
  • Tracing Paper: Semi-transparent paper. It’s used by designers to copy or overlay drawings.

Types of Board (Cardstock)

Boards are just thicker versions of paper (usually over \(200\) gsm—grams per square metre).

  • Folding Boxboard: Made of layers of printable surface and thick middle layers. It is excellent for retail packaging. Application: Cereal boxes.
  • Corrugated Board: This has a "fluted" inner layer sandwiched between two flat layers. It is very strong but lightweight and protects items from impact. Application: Amazon delivery boxes.
  • Solid White Board: A high-quality, strong, bleached board. It is very printable. Application: Book covers and high-end perfume packaging.

Key Paper/Board Properties to Know

  1. Flexibility: How easily the material can be bent or folded without breaking. Tracing paper is very flexible; thick corrugated board is less so.
  2. Printability: How well the surface of the paper or board accepts ink. Solid white board is designed to look crisp and professional when printed.
  3. Biodegradability: The ability of the material to be broken down by bacteria or other organisms. Most papers and boards are highly biodegradable because they are made from wood fibres.
Did you know?

Corrugated board is strong because of the "arches" in the middle layer. In engineering, an arch is one of the strongest shapes to support a load!

3. Quick Review: Which one should I choose?

In your exam, you might be asked to justify why a material is used. Here is a quick guide:

Question: Why use Stainless Steel for a spoon?
Answer: Because it is hard (won't scratch easily) and resists corrosion (won't rust when it gets wet).

Question: Why use Corrugated Board for a mailing box?
Answer: It has a high strength-to-weight ratio and provides impact resistance to protect the contents, while remaining biodegradable.

Question: Why use Copper for electrical wires?
Answer: It is highly ductile (can be drawn into wires) and is an excellent conductor of electricity.

Key Takeaways for Section A

  • Ferrous metals contain iron (rust/magnetic); Non-ferrous do not.
  • Understand the "Big Three" metal properties: Ductility, Malleability, Hardness.
  • Boards are categorized by their structure (e.g., corrugated for strength, solid white for printing).
  • Focus on Biodegradability and Printability when discussing papers and boards.

Note: If you want to learn more about other materials like plastics or wood, check out the next chapter: "Core materials: polymers, textiles and timbers".