Selecting Materials and Components
How a designer chooses the right material: matching properties to the functional need, weighing cost and availability, buying in standard stock forms, and understanding that many metals are alloys blended for better performance.
Justify the choices, the way you are assessed
Free interactive practice on the decisions the assessment actually asks you to justify.
Start revising freeWhat you'll cover
Choosing the right stuff
The best design fails if it is made from the wrong material. A good designer weighs up what the product needs to do, what it will cost, and whether the material can even be obtained. This module works through the factors in selecting materials and components, the standard forms materials are sold in, and why so many useful metals are alloys.
Selection words to know
Learn these before you choose a material.
A good choice against a poor one
The same three factors separate a wise material choice from a weak one.
Judge the material against the job
In the exam, judge a material against the job, not by habit. Ask three things: does it have the properties the product needs (functional need), can the maker afford it (cost), and can it be obtained in the right form and amount (availability). Remember that many metals are alloys, blended to make them stronger or more useful, and that materials are bought in standard stock forms such as sheet, bar and rod.
Match the factor
- functional need
- cost
- availability
- stock form
- the properties the material must have for the job
- how much the material adds to the price
- whether the material can be easily got
- a standard shape a material is sold in
Match the alloy
- steel
- stainless steel
- brass
- bronze
- iron mixed with carbon
- steel with chromium added
- copper mixed with zinc
- copper mixed with tin
Which factor is this?
Which factor is about whether a material can be easily obtained?
- Availability
- Functional need
- Aesthetics
- Cost
True about selection
Select the TWO true statements about selecting materials.
- Cost is a key factor when selecting a material
- An alloy is a metal mixed with other elements
- Functional need means the cheapest material always wins
- A stock form is a fault in the material
Work out the material needed
A designer needs 6 lengths of aluminium bar, each 500 mm long. Multiply the number of lengths by the length of each to find the total length of bar needed in mm. What is the answer?
Order the selection steps
Put the steps of selecting a material in order, earliest first.
- List what the product needs to do
- Decide the properties the material must have
- Check the cost and availability
- Select the best material and its stock form
Complete the rules
The job a material must do and the properties it needs is its _____ need. How much a material adds to the price is its _____. Whether it can be easily obtained is its _____. A metal mixed with other elements to improve it is an _____.
Spot the real factors
Tap the TWO things a designer checks when selecting a material.
- whether it has the right properties for the job
- whether it can be obtained at a sensible cost
- the favourite colour of pen on the desk
- how heavy the toolbox is
Make the choice
Read each case and choose the best answer.
- A material is perfect for the job but cannot be bought anywhere in time. Which factor rules it out?
- A part must resist rust in a kitchen sink. Which material would you choose?
- Brass is chosen for a fitting. What kind of material is brass?
Explain material selection
Explain the factors a designer considers when selecting materials and components.
- Explain functional need, cost and availability
- Explain what a stock form and an alloy are
- Give an example of choosing a material for a specific job