Iron Castings
Iron castings in grey (cast) iron and ductile (SG) iron are the most economical way to make strong, vibration-damping and wear-resistant parts such as machine beds, housings, pump bodies and pulleys. They are usually sand cast and machined.
What it is
Grey iron (for example FG 200–300 / IS 210) has graphite flakes that give excellent machinability, vibration damping and compressive strength. Ductile or SG iron (for example SG 400/12–600/3 / IS 1865) has graphite nodules that give much higher toughness and ductility, approaching steel.
Iron's low melting point and fluidity make it easy to cast into complex shapes at low cost.
Typical applications
- Machine tool beds and bases
- Pump and valve bodies
- Gearbox and motor housings
- Pulleys, flywheels and brake drums
- Agricultural and automotive parts
Suitable materials
- Grey iron FG 200, FG 260, FG 300
- Ductile iron SG 400/12, SG 500/7, SG 600/3
- Alloyed and wear-resistant irons
Points to consider
- Choose SG iron where toughness or impact matters; grey iron for damping and cost.
- Specify grade and whether test bars or microstructure checks are needed.
- Stress relieve machine beds before precision machining.
- Allow machining allowance and draft in the design.
Frequently asked questions
What is the difference between grey iron and SG iron?
Grey iron has flake graphite, giving good damping and machinability but low toughness. SG (ductile) iron has nodular graphite, giving much higher strength and ductility.
Why are machine beds made of cast iron?
Grey iron absorbs vibration well, is stable and machines easily, which suits machine tool structures.
Can cast iron be welded?
It is difficult and needs special procedures; castings are usually designed to avoid welding.