Materials and Their Applications

Comprehensive flashcards covering the physical and mechanical properties of materials, their classifications (metals, woods, polymers, composites, etc.), and both workshop and industrial testing methods.

What are the two principal categories of material properties?

Mechanical properties (associated with how a material reacts to an external force) and physical properties (associated with the actual make-up or structure of the material).

What is the standard stock size for medium density fibreboard (MDF)?

$2,440\,mm \times 1,220\,mm$.

What are the available standard thicknesses for MDF as mentioned in the text?

$25\,mm$, $18\,mm$, $15\,mm$, $12\,mm$, $9\,mm$, $6\,mm$, and $4\,mm$.

What is the definition of compressive strength?

The ability to withstand being crushed or shortened by pushing forces (compression).

What is the definition of tensile strength?

The ability to resist stretching or pulling forces (tension).

What is the difference between hardness and toughness?

Hardness is the ability to resist abrasive wear, scratching, or indentation, while toughness is the ability to absorb impact force without fracture.

What is the difference between ductility and malleability?

Ductility is the ability to be drawn out under tension (e.g., into a wire), while malleability is the ability to withstand deformation by compression without cracking.

What is the definition of fusibility?

The ability of a material to be converted from a solid to a liquid or molten state, usually by heat.

How does the manufacturing process differ between a galvanized low carbon steel watering can and an HDPE watering can?

The steel can requires multiple processes (cutting, bending, welding, galvanizing), whereas the HDPE can is made via a single process like blow moulding or rotational moulding.

What are the three sub-classifications of metals?

Ferrous (contains mostly iron and carbon), non-ferrous (does not contain iron), and alloys (a combination of two or more elements, one being a metal).

What is the approximate melting point of aluminium?

$660\,^{\circ}\text{C}$.

What is the difference between hardwood and softwood trees?

Hardwoods come from broad-leafed deciduous trees (slow-growing), while softwoods come from coniferous cone-bearing trees (fast-growing, usually evergreen).

What characterizes a thermoplastic polymer?

It can be repeatedly reheated and reshaped, allowing it to be recycled.

What characterizes a thermosetting polymer?

When heated, it undergoes a chemical change forming rigid cross links; it cannot be reheated or reshaped.

What is a composite material?

A material comprised of two or more different materials, resulting in a material with enhanced properties.

What is the definition of a smart material?

A material whose physical properties change in response to an input or change in the environment, such as electricity, pressure, temperature, or light.

What is the difference between a smart material and a modern material?

Smart materials react to external changes in the environment, whereas modern materials (developed through new processes) do not react to external changes.

In workshop testing, how is hardness tested for resistance to surface indentation?

By using a dot punch and a hammer to hit the material once with the same force; a smaller indent indicates a harder material.

In workshop testing for ductility and malleability, what do cracks on the outside and inside of a $90\,^{\circ}$ bend indicate?

Cracks on the outside indicate a lack of ductility; cracks on the inside indicate a lack of malleability.

What industrial test is used to measure the toughness of a material?

The Izod impact test, which uses a swinging pendulum to strike a notched test piece.

What are the three common industrial tests for hardness?

The Rockwell test (measures distance between preload and applied load indentation), the Brinell test (measures diameter of an indent from a steel ball), and the Vickers pyramid test (uses a diamond square-based pyramid).

What are the two standard methods of non-destructive testing (NDT)?

Ultrasonic testing (using sound waves and a transducer) and X-ray testing (projecting an image to see internal flaws like voids or cracks).

What formula is used to calculate resistance in industrial electrical conductivity testing?

Ohm's law: $V=IR$.