ponyboy302

can some one explain the difference in the different metals and finishes used on car parts .. such as steel ,aluminum ,billet ,cast iron ,forged,nodular iron,polished, powder coated etc.??? where is it best to use certain metals rather than others and when is it not such a good thing ?

stang8689

Polished is metal or aluminum sanded and buffed to a shine.

Billet is a type of metal with a low gloss polished lookin finish

Forged is the strongest metal over nodular, hyper, etc.

Power coated is when you bake the paint on with high temps for a durable finish and easy maitence

67mustang302

Aluminum is much lighter than iron/steel but not quite as strong(in most common alloy forms anyway, though aluminum is still pretty tough) but has much better heat conducting capabilities. Cast iron vs nodular iron(sometimes called cast steel) vs steel is determined by the content of carbon in the iron alloy. Cast iron is generally 2-4% carbon whereas steel is lower, around 0.5-1.5% carbon iirc. Nodular iron at it's highest carbon content overlaps some with cast iron, up to around 2.2 or 2.5% I think is still considered nodular(but is differentiated from typical cast iron based on the nodular structure of the carbon molocules, hence the term nodular). Cast metals are just poured into a mold and cool, forged are poured into a mold, or injected under pressure and then held under pressure as they cool, making them denser with more uniform grain structures, so they're stronger, but for the same volume are heavier because of the increased density, forged iron alloys also have a MUCH higher tensile strength than cast iron. Polishing is just making it shiny and smooth, which has advantages by removing any minor imperfections in the surface that could start stress fractures, powder coating is like painting in a way, but the object to be coated is magnetically charged and then the coating which is attracted to the charge is sprayed on and then baked, which causes the powder coat itself to bond to the surface of the material, very durable. As far as which to use depends primarily on the mechanical forces involved, heat and cost, as well as the necessity to maintain a certain weight