Stacking factor
The stacking factor is used in electrical transformer design. Since transformers are made up of metal sheets, almost always iron, they are laminated so they do not contact each other. This is done to reduce the intensity of eddy current losses in the core, while keeping a high flux carrying capacity. The lamination is not a ferro-magnetic material, therefore, when calculating the flux density of the iron core this must be taken into account. The stacking factor gives an approximate number to how much of the core is effective when calculating flux.