Construction and Processing materials over time
To get an understanding of the materials used in a motor vehicle, we look at parts and what they would have been made of.
Table of Contents
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Engine block
The desired materials for engine blocks should be:
- Able to be cast
- Able to be machined
- Resistant to high temperatures
- Resistant to impact loads
- Thermally conductive
- Able to retain its shape under many different circumstances
- Able to dampen the vibrations from the pistons
- Lightweight
Some of the materials used:
- Grey cast iron
- Great vibration dampening
- Heavy
- Usually cast in one piece, then machined if this is the case. Called a monoblock if done so.
- Aluminium alloys
- Lightweight
- Alloys create a variety of possible mechanical properties
- Some of the alloys used can be from Nickel, Chromium or Magnesium
- Usually Pressure or Gravity casted.
- Occasionally requires the use of cast iron inserts to withstand the loads.
Pistons
The desired materials for pistons should be:
- Able to be machined
- Resistant to impact loads
- Resistant to high temperatures
- Thermally conductive
- Able to retain its shape under varying circumstances
- Lightweight
Some of the materials used:
- Aluminium
- Lightweight and easily machinable
- Spray coatings may be applied to reduce wear on the cylinder walls
Crankshafts
NB: Crankshafts are those things that spin to move the pistons up and down.
The desired materials for crankshafts should have:
- High tensile strength
- High fatigue strength
- Shape stability
- Machinability
Some of the materials used:
- Cast iron
- Easy to cast into its intricate shape
- Good wear resistance
- Could be replaced with ductile Carbon steels
- Was used a while ago
- Alloyed steel
- Usually forged and then heat treated to appropriate qualities
- A common alloy is Vanadium
- Lightweight
- Better shape stability
- Impact dampening
Body Panels
The desired materials for body panels should have:
- Good strength to weight ratio
- Good surface finish
- Formability
- Toughness/Scratch resistance
- Corrosion resistance
- Weldability and Ease of manufacture
- Recyclability
Some materials used were
- Aluminium (Pre-1916)
- Steel and steel alloys
- High formability
- Alloys reduced weight while maintaining tensile strength.
- Stainless steels also reduce corrosion resistance.
- Alternatives such as Aluminium alloys and thermoplastics allow for recyclability and corrosion resistance.
Frame
Good frames should have
- Lightweight
- Stiffness
- Fatigue strength
- Weldability
- Corrosion resistance
Some materials used were
- Steel alloys
- Aluminium Alloys
- Joined with rivets as it is harder to weld
- Corrosion resistant
Windscreens
- Laminated glass was introduced in 1927.
- Tempered glass was introduced in the 1950s.
- It is used for rear windows as it obstructs vision.
Wheels
- In 1920s a solid disc riveted to the rim was introduced over the previous "axle goes immediately to tyre"
- This was better as they resisted the wheel flexing while turning.
- Today cast aluminium, fabricated steel or magnesium alloys are used
- Mostly cast aluminium alloys due to their formability, fatigue strength and impact resistance.
Tyres
- Originally, tyres had no tread pattern
- It was introduced in 1916, and vastly improved road-holding abilitiies
Good tyres have high
- Friction/Traction
- Wear resistance
- Shock absorption/Vibration dampening
- Abillity to not fail under petrochemical attacks.
Materials used include
- Rubber
- Universal material for tires
- New construction methods in 1948 (radial ply) helped improve passenger comfort and reduced wear.
QUICK SUMMARY
- All uses of timber have been replaced by iron, steel, and aluminium over time.
- Iron has been largely replaced by steel except in engine blocks which are still commonly cast iron.
- Aluminium and aluminium alloys have started to replace steel in areas where weight is an issue due to its better strength-to-weight ratio.
- Alloy steels with manganese etc have been developed for specialised uses over plain carbon steels.
- Stainless steel is now popular for cables and pins due to its high corrosion resistance.
- Carbon fibre is an excellent alternative to aluminium or alloy steel frames due to its high strength-to-weight ratio.
- However when it fails it is sudden and catastrophic.
- Rubber has been replaced with synthetic rubber.
- Polymers have found use where insulation is needed, or when high strength is not important
- eg cable coverings, dashboards, handles etc
Bicycle
- Timber: Used in early bicycles due to lack of suitable alternatives
- Iron: used initially on wooden wheels and in early frames
- Steel: Frames, wheel, spokes, tubing (good strength and relatively low weight)
- Usually steel frames were joined by brazing using lugs
- Extensively used in brake and gear construction until 1970s
- Ease of fabrication, reasonable strength, cost effective
- Alloy steels:
- Reynolds 531 is a manganese molybdenum steel that offered better strength to weight ratio than plain carbon steel
- Stainless steels:
- Reynolds 953 is a martensitic ageing stainless steel which offers UTS of up to 2000MPa
- Aluminium alloys
- Used widely in modern bicycles
- Reynolds 6061Al/Si/Mg: excellent corrosion resistance and workability
- Reynolds 7005 Al/Zn: greater strength but greater density
- Aluminium is light but considerably weaker, so tubes are not circular but oval to increase resistance to bending
- Titanium alloys:
- Expensive
- Must be welded with TIG method and done very carefully or there may be weld cracking
- Carbon Fibre Reinforced Polymer CFRP
- Excellent strength to weight ratio
- Easily moldable, ease of construction
- Tough and strong, however when the material fails it occurs though sudden catastrophic failure with little warning
- Rubber
- Replaced iron tyres
- Light and provided suspension
- Polymers
- Flexibility, lightweight, good resistance to deterioration
- Used in cycle lights, cables, finishing pieces
page revision: 13, last edited: 18 Feb 2021 03:39