Introduction to Selecting Materials and Components

Welcome! In this chapter, we are going to look at one of the most important parts of being a designer: choosing the right "stuff" for your product. Imagine trying to build a submarine out of cardboard or a wedding dress out of lead! It just wouldn't work, right?
Selecting the right materials and components is all about balance. You need to find the "Goldilocks" material—something that isn't too expensive, isn't too heavy, looks great, and does the job perfectly. Don't worry if it seems like a lot to think about; we will break it down into simple categories that you can use every time you design something.

Section Context: This topic is part of Designing and making principles. It's the "thinking" part of the project where you decide what to use before you start building.


1. The "Big Five" Selection Factors

When you are deciding on a material (like oak, acrylic, or steel) or a component (like a hinge or a screw), you should always run through these five main areas:

A. Functionality (How it Works)

This is the most important question: Does it do the job?
- Application of use: Is the material strong enough for what it needs to do? For example, a chair leg needs high compressive strength so it doesn't squash when someone sits on it.
- Ease of working: How easy is it to cut, shape, or join? If you are making a prototype in school, you might choose MDF instead of Oak because it's much easier to cut and sand quickly.

B. Aesthetics (How it Looks and Feels)

Designers want people to love their products. We look at:
- Surface finish: Is it shiny, matte, or rough?
- Texture: How does it feel to the touch? A phone case needs to be "grippy," while a kitchen worktop should be smooth and easy to clean.
- Colour: Does the material come in the right colour, or can it be painted/dyed easily?

C. Environmental and Ethical Factors

Modern designers must care about the planet. We consider:
- Recyclable or reused: Can the material be melted down and used again at the end of its life?
- Ethical sourcing: Was the material obtained fairly? A key term here is FSC (Forest Stewardship Council). If you see the FSC logo (a little tree), it means the wood comes from a forest where they plant new trees to replace the ones they cut down.

D. Availability and Cost

You can't build a product if you can't find or afford the materials!
- Availability: Is it "off the shelf" (easy to buy at a local shop) or a "special order"?
- Cost: Buying in bulk (large quantities) usually makes the price per item cheaper. Designers often calculate the cost of materials to make sure the final product can be sold at a profit.

E. Social and Cultural Factors

Does the material choice respect different cultures and beliefs? For example, some cultures prefer certain colours or materials for religious reasons, and a good designer is always sensitive to cultural influences.

Memory Aid: Use the acronym F.A.C.E.S. to remember these! Function, Aesthetics, Cost, Environment, Social.

2. Selecting for Prototypes (3.3.7)

When you are making a prototype (a first version or "test" model), your selection might be different than for a final product. You need to consider:

  • Functional need: Does the prototype need to actually work, or just look right?
  • Stock forms: Materials come in standard sizes like sheets, rods, and tubes. Choosing a material that is already close to the size you need saves time and reduces waste.
  • SI Units: We always measure in millimeters (mm) in D&T. Buying a 3mm thick acrylic sheet is a "standard" choice that makes planning easier.

Quick Review: Why would a designer use Cardboard for a first prototype instead of Steel?
Answer: It's cheaper, faster to cut (ease of working), and easy to find (availability).


3. The Maths Bit: Calculating Material Costs

Don't panic! The math here is very straightforward. You usually need to find the total cost by multiplying the amount of material by the price.

The basic formula is:
\( \text{Total Cost} = \text{Quantity Required} \times \text{Unit Price} \)

Example: If you need 3 meters of timber and it costs £4.50 per meter, the calculation is:
\( 3 \times 4.50 = £13.50 \)

Common Mistake to Avoid: Always check your units! If the price is per meter, but your measurement is in millimeters, you must convert them first.
(Remember: 1000mm = 1 meter).


4. Ecological and Social Footprint

Every material choice has a "footprint." Designers look at the Life Cycle of a product:
1. Sourcing: Where did it come from? (e.g., mining metal or farming trees).
2. Manufacture: How much energy was used to make it?
3. Transportation: How far did it travel? (Buying local reduces "product mileage").
4. Disposal: What happens when it's broken? (Landfill vs. Recycling).

Did you know? Using recycled components often uses significantly less energy than making new ones from raw materials. For example, recycling aluminum uses about 95% less energy than extracting new aluminum from the earth!


Summary Checklist - "Key Takeaways"

- Always choose materials based on Function first—it has to work!
- Use Aesthetics to make the product appealing to the user.
- Look for the FSC logo to ensure wood is ethically sourced.
- Consider Cost and Availability to ensure the project is realistic.
- Think about the End of Life—can the materials be recycled or reused?

Don't worry if this feels like a lot to juggle. As you practice making your own products, picking the right materials will start to feel like second nature!