IMHO- cymbals cast from a mold sound and feel MUCH better than cymbals that are stamped from a large sheet.
Just so you understand...
With the exception of UFIP and we'll get to that...
The terms 'cast' and 'sheet' were developed by marketing agents not manufacturers, and neither accurately describes either method of cymbal making. "Cast" cymbals are not cast into the shape of a cymbal, nor are "sheet" cymbals merely stamped from common sheetmetal.
Cast cymbals - molten bronze, an alloy of tin and copper, is poured into individual blobs about 4"-6" in diameter and about 1-2 inches thick. These 'castings', which is where the name comes from, are called ingots, and each one yeilds one cymbal. The ingots are repeatedly heated and passed through a series of rollers which flatten them into large, thin discs. Using a hydraulic press, the discs have their bells stamped and their initial profile established. The hole is punched, the edges trimmed, and then the discs are ready for cold-working...hammering. After hammering, the cymbals are lathed to their appropriate thickness, then aged.
Sheet cymbals - start as discs cut by an outside fabricator, from large plates of bronze. Because each plate yeilds several cymbals, and the process used to produce each plate is more strictly controlled than the process applied to 'cast' cymbals, 'sheet' cymbals have a justified reputation for being more 'consistent'.
It's like making cookies....
Cast cymbals are drop-cookies, where each cookie starts as a little ball of dough. Sheet cymbals start with a similar dough, but rather than little individual balls, you roll out a large, thin sheet of dough and cut smaller cookies from it.
After you have the thin disc, whether a flattened blob or one cut from a plate, the manufacturing process is very similar...shaping, tempering, cold-working, finishing.
UFIP...
do cast a disc in the shape of a cymbal, using a method called centrifugal-casting, a mold in the shape of cymbal is spun at a high speed, while being filled with molten bronze. Once cooled, the casting resembles a completed by rather thick 'cymbal'. It is then annealed, hammered, and lathed like any other cymbal.