Physical & Working Properties in Depth
Physical and Working Properties in Depth
The core content introduces the main materials in each category, but the specialist section pushes further. This lesson looks at extra metals, papers, polymers, systems components, textiles and timbers you need for your chosen material category, and the physical and working properties that let you compare any material scientifically.
Advanced Metals: High Carbon Steel, Tungsten Steel & Titanium
High carbon steel contains more carbon than mild steel. This makes it very hard and able to hold a sharp edge, but also brittle, so it is used for cutting tools, chisels and blades rather than structural parts that might bend. Tungsten steel is an alloy of steel and tungsten. It keeps its hardness even at high temperatures caused by friction, which is why it is used for high-speed cutting tools and drill bits.
Titanium is light, strong and highly resistant to corrosion. These properties make it ideal for aerospace parts and medical implants such as hip replacements, where the metal must not react with the human body. Its main disadvantages are cost and the difficulty of machining it, since it work-hardens quickly and generates a lot of heat when cut.
High carbon steel is hard but brittle; tungsten steel stays hard at high temperatures; titanium is light, strong and corrosion-resistant but expensive to machine.
Papers, Boards and Packaging Laminates
Beyond copier paper, cartridge paper, tracing paper, folding boxboard, corrugated board and solid white board, the specification also covers foil-lined board and packaging laminate, the material used for cartons like Tetra Pak. Combining several materials in one laminate gives packaging properties that no single material could offer on its own.
Physical characteristics used to describe paper and board include density (how heavy the material feels for its size), transparency and surface texture. These characteristics affect how well a material prints, folds or bonds to other layers without cracking.
A carton of long-life milk needs to be rigid, leak-proof and keep out light and oxygen so the contents do not spoil without refrigeration. Paperboard gives the structure and a printable surface for branding. A thin layer of polyethylene bonds the layers together and seals against liquid. A layer of aluminium foil blocks light and oxygen. Together, the laminate does a job that paperboard alone could never do.
Additional Thermoforming Polymers: ABS, PET & PVC
Acrylonitrile-butadiene-styrene (ABS) is tough and resistant to impact, which is why it is used for products that get knocked around, such as construction bricks and power tool casings. Polyethylene terephthalate (PET) is lightweight, transparent and can be blow moulded into thin-walled shapes, making it the standard choice for drinks bottles because it also resists gases escaping or entering.
Polyvinyl chloride (PVC) can be manufactured as a rigid or a flexible polymer depending on the additives used, so the same base material is used for both drainage pipes and flexible cable insulation. When comparing polymers for an exam answer, always link the property, such as tensile strength or impact resistance, to the actual use of the product.
ABS resists impact and suits casings; PET is blow moulded into drinks bottles; PVC is made rigid for pipes or flexible for cable insulation.
Systems: Microcontrollers and PIC Chips
A microcontroller, often called a PIC, is a control device that gives a product its programmable behaviour. Instead of wiring separate switches and logic gates for every function, a single microcontroller can be programmed with a flowchart-based routine that reads inputs, makes decisions, and switches outputs on or off, including delays, loops and counts.
Additional Textiles: Regenerated Cellulosic Fibres
Viscose, acetate and Tencel are examples of regenerated cellulosic fibre. They start life as wood pulp or cotton linters, which are dissolved and pushed through tiny holes to form new fibres. This gives them a soft handle and good drape like a natural fibre, while offering some of the consistency of a synthetic fibre, which is why they are often used for linings and lightweight clothing.
Natural fibres like wool and cotton absorb moisture well but can lose strength when wet. Synthetic fibres like polyester and nylon keep their strength when wet and resist creasing, but do not breathe as well. Regenerated fibres like viscose sit in between, offering comfort closer to natural fibres but with some of the manufacturing consistency of a synthetic. Choosing between them means weighing elasticity, breathability and durability against the end use of the product.
Additional Timbers: Jelutong, Larch & Chipboard
Jelutong is a pale, straight-grained hardwood that is very easy to carve and shape, so it is often chosen for pattern-making and modelling rather than finished furniture. Larch is a durable softwood that resists rot even outdoors, making it a common choice for cladding and fencing. Chipboard is a manufactured board made from wood chips bonded together with resin under heat and pressure. It is cheap and available in large flat sheets, which is why it is widely used as the core material in flat-pack furniture.
Physical & Working Properties: The Common Language
Whichever material category you study, compare materials using the same properties. Density tells you how heavy a material feels for its size — useful when comparing a lightweight polymer casing to a heavier metal one.
Conductivity explains why metals are chosen for wiring and heat sinks, while polymers and timbers are chosen as insulators to keep people safe from heat or electric shock. Tensile strength, covered above, explains why some materials are chosen for structural parts that get pulled or stretched.
Density, conductivity and tensile strength are physical and working properties used to justify material choice across every category in the exam.