Stock

Stock is the raw material a part is machined from before any material is removed: a bar, plate, block or casting of a specific size, larger than the finished part to leave material for machining. Stock size and shape directly affect both material cost and how many operations are needed to reach final geometry.

Why stock size is a real decision, not just a starting point

Choosing stock that is too close to final size can leave no margin for distortion or setup error, while stock that is too large wastes material and adds unnecessary material removal time, so stock sizing is itself a small optimization problem.

Where stock size comes from

Not usually shown directly; inferred from the part's overall envelope plus a margin, and sometimes specified explicitly for cast or forged starting stock.

Common mistakes

Assuming standard stock sizes always exist close to what a part needs; an odd finished size can force using a larger standard stock size, adding material cost and removal time that a design change could have avoided.

Is stock the same as raw material?

Stock is raw material sized and shaped as the specific starting point for a specific part, before machining begins.

Does stock size affect the price of a part?

Yes, both directly through material cost and indirectly through the machining time needed to remove the extra material.

Why not always use stock exactly at final size?

Because some margin is needed for machining, alignment error and, in castings and forgings, dimensional variation from the raw part.