Materials Flashcards
Name some permanent joining methods (explain if necessary)
Welding - process that joins metals by using high heat to melt the parts together and allowing them to cool, causing fusion. (Distinct from lower temperature methods)
Brazing - metal-joining process in which metal items are joined together by melting and flowing a filler metal into the joint.
Silver Soldering
Epoxy Resin - Their physical state can be changed from a low viscosity liquid to a high melting point solid, which means that a wide range of materials with unique properties can be made. In joining, they are commonly used as glues and adhesives due to their properties.
Name some temporary joining methods (explain if necessary)
Nuts + Bolts
Self-tapping bolt
Cutting threads (Tap + Die)
What is Hot/Cold Working?
The terms hot and cold working mean that pressure has been applied to the surface of a metal to improve its properties. When the metal is heated during hot working it causes the surface atoms to recrystallise giving the metal different properties that when cold working makes the metal harder. Overall both processes increase the ductility, hardness and strength of the metals.
What is Casting?
Casting processes involve the use of molten material, usually metal. This molten material is then poured into a mould cavity that takes form of the finished part. Casting is generally quite a complex process due to the complex metallurgy of using molten metal.
What is a Lathe?
Lathe is used for turning materials so multiple operations can be performed (using specific tools) to produce various features.
What is Milling?
CNC machining is a cutting technique. There is a revolving cutting tool present. It revolves and travels over a static clamped part. The tool contains multiple cutting edges that removes chips from the material.
Properties of aluminium
- 100% recyclable
- Malleable
- Excellent strength to weight ratio
- low density
- corrosion resistant
Properties of steel
- Hard
- Dense
Properties of brass
Sonorous, ductile, excellent conductor, malleable
What is a thermosetting plastic?
- These polymers can be heated and formed into a specific shape - often complex shapes.
- On cooling these polymers cannot be reheated or reshaped.
- Difficult to recycle
- Strong and heat resistant but can be brittle (mostly used as adhesives)
Examples: Epoxy resin, MF, UF
What is a thermoforming polymer?
- Thermoforming polymers can be heated and formed repeatedly
- Pliable and recyclable
Examples: Acrylic, HDPE, PP, PVC
Properties of acrylic
- durable
- water resistant
- available in many colours
- easily scratched
