Hi KP,
If you don't want raw materials to be updated in standard cost, in CK40N - maintain SFG and FG material types. Here, it will release the standard cost only for semi-fin and finished goods.
If raw material master updated with S also, will not give any issue while rolling up the cost to next level as its consider the material prices based on price strategies of valuation variant.
BR, Srinivas Salpala