The core of WIP logic (work in process) is made by the allocation of value to stored items between production phases. Money is wasted when in work products or components lie unused e.g. in a trolley used as a buffer. If a manual transfer line is used, only a small quantity of in work products lies waiting between production phases. This problem is amplifi ed if a mistake made in one phase remains unnoticed until a trolley full of defi cient components is brought to the next phase. In manual transfer solutions, since only a few faulty products can be produced before the mistake is noticed both the cost per mistake and the number of mistakes are greatly minimized.