By the end of this component, students will be able to explain why and how materials are selected and how they enable outcomes (technological products) to function as expected.
Technological products are material objects that have been designed by people and developed through technological practice to serve particular functions.
A crucial relationship between the (chemical) composition and structure of the materials used and their performance properties exists in every technological product.
For this reason, students (technologists) need to be able to evaluate different materials and select the most suitable for their purpose. Students also need to understand how:
- existing materials can be modified
- new materials formulated
- their choice of materials impacts on the design, development, maintenance, and disposal of their outcome.
The benefits of learning about technology products
The intent of technology learning is for students to grow capabilities that support them to "intervene by design".
By understanding how materials are made, how they are structured, how they perform, and how they can be manipulated, students can be innovative and develop successful outcomes.
Products and systems
Technological outcomes can be classified as products or systems, or both. In this component, the focus is on technological outcomes as products and, more specifically, their material natures.
Characteristics of technological outcomes – information about key ideas, examples, and sources related to characteristics of technological outcomes.
The Technological products component is about the identification, description, use, and development of materials. It it also about the impact that selection of materials has on the fitness for purpose of technological outcomes.
Different products require different knowledge bases, depending on the kinds of materials to be used. For example, the knowledge bases required for understanding and developing garements, food products, or furniture will all be very different.
All materials have properties that can be measured objectively or subjectively – these collectively determine the overall performance properties (characteristics such as thermal conductivity, water resistance, texture, flexibility or colour) of a material.
People perceive properties such as taste, feel, texture, or ease of use differently, so they can only be measured subjectively. However, properties such as conductivity, UV resistance, tear resistance, or tensile strength can be measured objectively using appropriate equipment calibrated to an established standard.
To be fit for purpose, a product must be made of materials that will:
- enable its successful functioning
- make it acceptable to users (safe to use, environmentally friendly, economically viable, ethically sound).
The type and arrangement of the particles that make up the material – in other words, their chemical composition and structure –determine material properties.
Materials can be formed, manipulated, and transformed to enhance the fitness for purpose of a technological product.
Forming involves bringing two or more materials together to create a new material that has a different chemical composition and structure and, as a results, a different performance properties.
- mixing flour, water, and salt to make dough
- mixing wood fibres, resin, and wax to make medium-density fibreboard (MDF)
- combining glass fibre and a polymer resin to form fibreglass or fibre-reinforced polymer (FRP).
Manipulating involves working existing materials in ways that do not change their composition and structure or their properties.
Instead, manipulation allows the material to be incorporated into a product in ways that maximise its contribution to the overall performance of the product.
Manipulation can involve actions like laminating materials, changing the shape of materials, or joining different materials together. Cutting, moulding, bending, jointing, gluing, and painting are also examples of manipulative operations.
Transforming involves changing the physical structure or particle alignment of a material (and therefore, some of its properties), without changing its chemical composition.
- beating an egg white
- heat-treating a metal to harden or anneal (strengthen) it
- steaming timber to soften its fibres so that it can be manipulated (bent).
When developing technological products, the techniques and operations can involve a combination of forming, manipulation, and transformation.
Evaluating and selecting materials
For any technological product, materials are selected because their performance properties will help ensure that the product meets the required performance criteria.
Some material properties (for example, wood grain or colour) may be valued for what are fundamentally aesthetic reasons.
Materials need to be properly evaluated so that those selected can be justified as optimal (not merely satisfactory), taking account of all the relevant factors.
When evaluating the suitability of materials, you must understand their composition as well as the techniques and procedures used to form, manipulate, and transform them.
Technologists often use specialised language and symbols to communicate specific information about materials.
Today, materials development cuts across boundaries between traditional disciplines. This leads to the creation of innovative materials (for example, “smart” materials) with exciting performance properties and to the development of technological products that perform new functions.
Developers looking to create new materials must:
- first know the strengths and weaknesses of existing materials
- understand how chemical composition and structure can be changed
- be able to anticipate future needs and desires.
They also need to be aware that new evaluative procedures may need to be devised to assess the suitability of new materials.
The development of “smart” materials with totally new performance properties opens up opportunities for the development of new kinds of products.
What makes a material “smart” is its ability to change or adapt in response to an external stimulus (trigger) or input, which may be technological, environmental, or human. The stimulus causes a transformation in the properties of the material itself.
Products developed using smart materials include heat-regulating clothing, light-responsive sunglasses, artificial muscles, self-cleaning textiles, self-adjusting optical lenses, colour-changing shirts, and self-healing paint.
Impact of materials selection
Materials selection, evaluation and development has a major impact on product design, development, maintenance, and disposal.
By examining this impact, the students gain an understanding of sustainable practices, such as resource management, life-cycle design, and disposal, which are all critical factors to consider in product design decisions.
Acknowledgment: This paper is derived from an earlier version by Dr Vicki Compton and Cliff Harwood.