Materials

Table of Contents

Fork me on GitHub

1 Introduction

  • When creating a new product, one consideration is what to make it from. When choosing a material, there are a number of considerations. How should it look when it’s finished (aesthetics)? Can it be formed and joined in the way you want it to? Is it strong enough for the task? Is it cost-effective? Is the material “sustainable”?

Task: Complete the following tables, using the Internet and text book to help you.

Common woods

  • Woods come from trees, which are chopped down, then worked into sheets of wood, or planks. As a natural product, they are sustainable (if the forest they come from is being re-planted), and have an attractive grain in the wood.
Wood Category Colour Properties Common Uses
Pine     Durable, machines well  
Oak       Furniture Making
Beech   Light brown    
Larch Softwood      

Manufactured boards

  • Man-made boards are those which are produced in factories. They tend to have a uniform appearance, and have unique properties.
Board Colour Properties Common Uses
Cardboard      
MDF     Cupboard doors
Plywood   Strong; comes in different finishes to improve appearance  
Chipboard Brown, with a coarse texture    
Hardboard     Furniture, flooring construction

Plastics

  • Often derived from oil, plastics provide a variety of durable materials which can be formed easily into whatever shape is required, and can be highly durable. Their relatively low cost has led to their popularity for use in all manner of every day objects. Unfortunately, plastics tend not to be easily bio-degradable (often taking several hundred years to break down in landfill), and as such need to be recycled wherever possible.
  • Plastics can be either classed as thermosetting, or thermoplastic. When forming them into a shape, Thermosetting polymers normally need to be mixed with a curing agent, which allows them to set solid. Once set, they cannot be re-formed into another shape. Thermoplastics can be repeatedly heated until soft, then cast into a new shape and cooled.
Plastic Category Properties Common Uses
Acrylic Thermoplastic    
ABS   High impact resistance, strong  
HIPS     Packaging
PP     Plastic pipes, school chairs
Nylon   Hard wearing  
Urea Formaldehyde Thermoset    

2 Metals

  • Metals come from ores which are dug from the ground, and purified. They can be cast into sheets, or ingots ready for forming into different shapes.
  • Some metals can be combined with other materials to form alloys, which have new, unique properties. Steel is made by combining iron and carbon, for instance.
  • Ferrous metals are those which contain iron.
Metal Category Colour Properties Common Uses
Copper Non-ferrous   Excellent electrical and thermal conductor  
Mild Steel       Nuts, bolts, etc
Aluminium   Grey    
Stainless Steel Ferrous      

Smart Materials

Material Properties Common Uses
Smart memory Alloys Can be bent out of shape, but returns to original shape when heated.  
Piezoelectric materials   Mics, speakers, alarm systems.
Quantum Tunnelling compsite An insulator which becomes a conductor when put under pressure.  
Electroluminescent Materials   Safety clothing, safety lights.

3 Understanding Check

Past Paper Questions

June 2010, Q5a. This question is about programming a greenhouse temperature / environmental control system model. The greenhouse model has a heat sensor, and a roof vent that opens and closes to regulate the temperature.

(a) (i) Suggest a specific material for the greenhouse frame. (2 marks)

(a) (ii) Explain why the material that you have selected is suitable. (2 marks)

(a) (iii) Suggest a suitable component to sense that the roof vent is closed. (2 marks)

June 2011, Q4a. This question is about a washing machine control system model. The washing machine model is made from plywood and has: -

  • a door that opens and shuts
  • a button to start the simulated wash
  • a door lock to stop the door opening
  • a geared motor to turn the wash drum
  • an LED that lights to show that the drum is turning.

2011_q4a.png (a) (i) Suggest a suitable plastic for the window in the door. (1 mark)

4 (a) (ii) Explain why the plastic you have named is suitable. (2 marks)

4 (a) (iii) Suggest a suitable component to operate the door lock. (1 mark)

Return to homepage