Lesson video

Hi there, my name is Mr. Booth, and welcome to your design and technology lesson for today.

It's fantastic you could join me.

We've got a great lesson today, all about selecting materials for manufacture.

It's important that we consider all the different factors when selecting materials before we actually manufacture it.

This is part of the materials testing unit.

Today's outcome, I can explain how a range of factors affect the selection of materials for manufacture.

We have four keywords for you today.

The first is all about performance, how well a material does its job and meets the needs of the product.

We then have cost, the price of buying, processing, and using a material during manufacture.

Sustainability, really important, a product or material that has minimal environmental impact through its reuse or replenishment.

And then, finally, properties, the characteristics of a material, like hardness, weight, or conductivity, that determine how it looks, feels, and behaves when used in our products.

We have two learning cycles today.

The first is all about how material properties influence choice, so let's make a start.

Industries select materials based on several key factors, ensuring final product is functional, cost-effective, and sustainable.

There are three main factors in material selection, and they are performance, how well the material meets the functional needs of the product, how well it actually does its job, cost, the price of the material and how it affects manufacturing, and of course, sustainability, the environmental impact of sourcing and also using that material.

Performance refers to how well a material does its job, and it's linked to the material's properties.

Now there are two categories of material properties.

We have the physical properties and also the working properties.

Now the physical properties are all about their appearance and their characteristics, and the appearance, such as things like texture or transparency.

And then, of course, we have the working properties, the behavior of that material when certain loads are applied, like forces and things like that, but also, they are sometimes referred to as mechanical properties as well.

Quick check for understanding.

I would like you to fill in the blanks using the words on the right.

So we have our physical properties, and we have our working properties, and the words you have to choose from are behavior, appearance, characteristics, and mechanical.

So fill in the blanks, pause the video now, come back to me when you've answered.

Well, hopefully you filled it in.

So for physical properties, we have got appearance and characteristics, and for working properties, we've got behavior and mechanical.

Well done.

Physical properties refer to the characteristics of a material, such as appearance and its features, and examples of this include conductivity, and we can split that into two, the thermal conductivity, how well it conducts heat, and electrical conductivity, how well it allows electricity to flow through it.

We have the density, the color, the weight, the texture, and also the absorbency.

Now these words describe the material before its use.

That's a physical property.

Working properties, on the other hand, refer to the way a material behaves when subjected to an external force, for example, like bending or in environmental situations, for example, like moisture if it's been left out in the rain, and examples of these properties include strength.

Remember, we've got tensile strength, so that pulling force or compressive strength, that pushing force, flexible, elastic, durable, tough, and also, hard.

Now we also have moldable and malleable.

Now malleable refers to metals only.

For other materials, for example, like polymers, they are moldable.

And, of course, these words can also be described as mechanical properties because they describe the material's behavior during its use.

Quick check for understanding.

Which material property is most important for making electrical wires? So think about the function of the material.

Is it A, durability, B, electrical conductivity, C, flexibility, or D, weight? Pause the video now, have a go at this, and come back to me when you've got your answer.

It is, of course, electrical conductivity.

Well done.

A material's physical or working property will determine its performance.

Some key considerations that we need to think about are strength, can it withstand forces without breaking, flexibility, can it bend without snapping, durability, how long is it gonna last before wearing out or breaking? If you think about aircraft, parts are made of aluminum because they need to be light but also strong.

Aluminum has what we call a good strength-to-weight ratio.

Bridges are made of steel and concrete because they must handle high weight loads and last for a very long time, and actually steel, and especially concrete, have very high compressive strengths.

Different industries rely on materials with specific physical and working properties.

As we know, aerospace needs to be lightweight but strong, for example, like carbon fiber is used a lot.

Construction needs durable, weather-resistant materials.

Concrete is perfect for that.

And, of course, fashion wants flexible and soft materials, such as things like cotton for T-shirts.

Another check for understanding.

What I want you to do now is match the material to its most important property.

So we have glass, rubber, steel, and cotton, and the properties are flexibility, strength, softness, and transparency.

So match the materials to the most important property.

Pause the video now, have a go at this.

Well, we have glass, and I think the most important property for that is transparency, and of course, we're talking about windows there, aren't we? We have rubber, which is flexibility, and we might be talking about car tires.

We have steel, which is strength, and we've already talked about construction, like bridges, and finally, cotton, softness, of course, if we're talking about things like T-shirts.

Well done.

So we're on to your first task now.

I want you to look around your classroom and choose one product.

Identify the material that the product is made from.

I want you to explain why this material was chosen, considering performance, how well the material functions for its purpose, cost, how affordable or cost effective is the material to produce or buy.

And then, finally, the last two, I want you to suggest an alternative material that could be used instead and explain why this alternative was not selected as the main material.

Pause the video now, have a go at this task, and come back to me when you've completed it.

So how did you get on? Well, let's have a look at a sample answer.

So you might be sat at a workbench now, and that might be a beech workbench, so that's the material.

The performance, well, it's strong, it's durable, and it's resistant to impact, all important when we're using all those tools on it.

It provides a smooth, stable surface that doesn't warp easily.

Cost, well, it's more affordable and widely available than other hardwoods like oak or maple.

Now an alternative could be steel, but of course, steel is strong, but it's heavier, it's more expensive, and it's much less comfortable to work with.

It's very cold to the touch.

So beech offers a better balance of performance, cost, and also usability.

Well done with that task.

So we're now onto the second learning cycle, the other factors that influence material choice.

As well as performance, industries consider other factors when selecting materials for products.

These include cost, how expensive the material is to buy, process, and manufacture, and also sustainability, the environmental impact of that material.

Now this will include how it's sourced, how it's produced into a workable material, but also how it's disposed of once the product has been used.

Quick check for understanding.

Which of these is not a key factor in material selection? Is it A, cost, B, color, C, performance, or D, sustainability? Pause the video now, have a go at this, and come back to me when you've got your answer.

It is, of course, color, B.

Well done.

Now industries must consider the cost of materials because it affects the overall price of the product.

Factors that influence cost, well, raw material cost.

So some materials like gold or titanium are very expensive.

There's also processing cost, how easy is it to shape, cut, or mold? If you've gotta heat the material to a very high temperature, that's gonna use a lot of energy and cost a lot of money.

Now gold is an excellent electrical conductor, and it is used in high-end electrical goods, but it's very expensive.

Now polymer garden chairs are cheaper than timber or metal, as they are easier to mold.

They're much quicker and easier to mold.

You don't need to heat them to a higher temperature, and also, shaping timber is much more complicated.

Car manufacturers use different materials depending on the type of vehicle and its purpose, and this, obviously, is all about cost.

So you can see we've got a family car, where steel is probably used 'cause it's budget-friendly, but it's obviously due to its strength as well and its low cost.

We then have higher-performance cars, where aluminum is probably getting used, and that's because it's lightweight, but it's also corrosion-resistant.

And then if we're talking about racing cars, they want maximum performance, and what they're gonna use is carbon fiber.

It's got a very high cost, but its strength-to-weight ratio is significantly higher than aluminum and steel.

Sustainability means choosing materials that reduce harm to the environment.

Factors in this include renewability, can the material be replaced that we are using, for example, wood versus plastic.

Recyclability, can it be reused instead of going into waste? And also carbon footprint, how much energy is used to produce it? And if we look at an aluminum can as an example of this, recycled aluminum requires less energy to produce than new aluminum.

Producing aluminum uses a lot of energy.

And also, things like disposable cutlery.

Bamboo is replacing plastic because it grows quickly and also it's biodegradable.

So next time you go into your local takeaway, you might find it's bamboo instead of a polymer.

Now in a school workshop, cost is often the most critical factor when selecting materials because, of course, the department must work within a limited budget, sometimes an extremely limited budget.

Schools aim to select materials that are affordable, easily sourced, but also, just to make sure that students can work with them easily and safely.

And, of course, you might have worked with pine or Scots pine, it's easy to work with, and it's relatively cheap.

Copper is also what we call a soft metal, so it's easy to work with, and you might, if you've done anything with textiles, use some cotton.

As a result, schools typically select the most cost-effective materials that still meet the project's performance requirements.

Resources are utilized efficiently while still enabling students to acquire knowledge and the skills needed.

So we're now onto task B.

A pupil wants to make a camping stove.

The stove will be made by hand using workshop tools.

The two material options are aluminum sheet, which comes in 1,000-by-500 millimeters, and it comes in 22 swg, which stands for standard wire gauge, and that's how we measure certain sheet materials, and that actually means it's about 0.

7 millimeters thick, and it's a cost of 12 pounds 47.

We also have low carbon steel, also known as mild steel.

This sheet comes in the same size in terms of the 1000-by-500 millimeters, but it's slightly thicker at one millimeter, and it's slightly cheaper at 11 pounds 40.

Questions I'd like you to answer.

Using research, I want you to compare each material for suitability for the product, the camping stove, and also, the manufacturing methods.

Remember, it's being made in a school.

I need to select a material and justify your choice.

You need to consider material performance, cost, and of course, sustainability.

Pause the video now, have a go at this task, and come back to me when you've made your justified choice.

So how did you get on? Well, let's have a look at what I decided.

So, first of all, I looked at aluminum and steel.

Well, aluminum has very good strength, toughness, and is lightweight when compared to other metals.

It has very good corrosion resistance and can be easily recycled.

It's easy to work with when manufacturing.

It is slightly more expensive than low carbon steel.

Low carbon steel has very good strength and toughness, but it's heavier than aluminum.

It has poor corrosion resistance and is prone to rusting easily.

Low carbon steel can be easily recycled and is cheaper than aluminum.

So my choice, well, aluminum is the better choice for this project because it meets all the performance requirements, strength, toughness, and corrosion resistance.

Although slightly more expensive, it will be easier to work with during the manufacturing processes that are taking place in a school workshop.

And I'm sure you made the same decision.

Well done with that task.

So that brings us to the end of this lesson.

Materials for manufacture are chosen based on performance, cost, and sustainability to ensure products are functional, affordable, and environmentally responsible.

Physical and working properties like strength, flexibility, and durability determine how well a material performs. And finally, manufacturers must balance trade-offs between performance, cost, and sustainability when selecting materials for various applications.

Well done today.

You've been absolutely fantastic.

I look forward to seeing you all next time.

Goodbye.