The basic principles of casting

The easiest process to  get your shaped product whether it is complex or not is casting.You pour the molten metal simply in mould it gets solidified and tada!!! You get your product.
Looks simple but Casting not only depends on how you solidify or how grains align themselves but it is a lot more, how you set the whole tool and design the pattern along to get the product.
Before learning what it actually involves in depth, it is better to get the brief idea of some basics.
You have your molten metal and mold cavity.
But what you also need to learn some important principles of design that affect casting.

1. External corners must be rounded.

    Why?The stress concentration .The rounded corner decreases stress localization and reduces the brittle chilled edges.
2. The loaded part better to be in compression.
  Especially in cases in which material performs better in compression like Cast Iron.
If still the part need to be in tension then a restricting device that compensates the effect of tensile strain must to be present.
So,a clamping device is needed.
3.Changes in area better to be uniform rather than abrupt.
  Again stress concentration.
4.Avoid  a lot of metal accumulation at junctions.
  It is because the core may not solidify at the junction and it can cause blow holes too.
5.Avoid thin castings.
  Why?Because the strength is decreased.You can get better strength thin sections formed by metal forming processes because the directional orientation  of grains after forming process is much more in continuous flow rather than that of casting process.
6.Shot blast the parts.

It increases fatigue strength..The beauty of shot blasting are the steel shots.These steel shots strike the work piece due to centrifugal action and increases it fatigue strength.It must be done to ensure the strength of the casting as they can subjected to cyclic loads.

The grain flow due to forging.