Material Properties
Define "weight"
The pull of gravity on an object
What are three key differences between softwood and hardwood.
- Hardood grows more slowly than softwood.
- Hardwood had a denser structure/fibres.
- Hardwood has a higher tensile strength/is stronger.
What is FDM also known as?
3D printing.
What is design for disassembly and its main advantage?
Designing a product so that it can easily and economically be taken apart,
the components can be reused or repaired, and the materials recycled.
What is the difference between Thermoplastics and thermosets?
Thermoplastics can be heated and shaped/re-shaped over and over again while thermosets cure and cannot be reshaped once set.
Define Hardness
The resistance a material offers to penetration or
scratching.
What is plywood and what is it's main advantage.
Plywood is a laminate/consists of thin layers of wood glued together.
The grain direction of each layer is turn through 90 degrees giving it multi-directional strength.
Define design for manufacture.
design specifically for optimum use of existing manufacturing capability available.
What is mechanised production?
A volume production process involving machines controlled by humans.
What is the result of interlocking synthetic or natural fibres?
Yarn
What is the difference between elasticity and plasticity?
Elasticity (elastic region) is the ability for a material to return to its otiginal shape after stretching while plasticity (plastic region) is the ability of a material to be changed in shape permanently.
What is the composition of glass?
Silica, Soda ash, limestone, and cullet (Crushed waste glass from manufacturing scrap or post-consumer recycling)
What is one advantage of subtractive manufacturing?
High accuracy.
• High quality finish.
• Produces very fine details.
• Minimal distortion.
• Produces very fine details.
• In combination with CAM allows for 24/7 production
Two reasons why aluminium is a better choice than steel for the manufacturing of cars.
- It is lighter
- It doesn't corrode as easily
What defines the grain size in a metal?
The speed at which it is cooled after being heated and shaped.
What is the yield point of a material
At the limit of it’s elastic region (the elastic limit /Yield point) a metrial will hit the plastic region; the material deforms plastically and does not return to its original length or shape.
What is work hardening and why is it done?
Once quenched, metal is reheated to a lower temperature and allowed to cool slowly.
This reduces the brittleness incurred through quenching improving toughness
What is SLS and its main advantage?
Selective laser sintering
I requires no support material hence not waste is produced.
What are the 4 categories of Design for manufacture?
DESIGN FOR MATERIALS
DESIGN FOR PROCESS
DESIGN FOR ASSEMBLY
DESIGN FOR DISASSEMBLY
What are 3 advantages of using polyester in t-shirt.
- it is cheaper than natural fibres
- it is more durable
- it reduces water absorbence
Define photochromicity.
When a material changes in their opacity/tint when exposed to light/UV rays.
What is strain hardening of a metal?
The process of toughening a metal through plastic deformation. It makes the metal harder and stronger through the resulting plastic deformation.
What are the 4 main manufacturing techniques?
Joining techniques
Additive techniques
Subtractive techniques
Shaping techniques
What is parison blow molding?
Parison blow moulding is a manufacturing process used to make hollow plastic products by inflating a heated plastic tube inside a mould.
What do you call the substance that holds a composite together?
Matrix