BS EN IEC 63093-1:2020 pdf free.Ferrite cores – Guidelines on dimensions and the limits of surface irregularities  General specification.
These surfaces are generally ground in order to limit the residual air gap between the twocore halves. Consequently, irregularities on these surfaces have to be considered as majorones,and carefully evaluated with regard to their influence on the magnetic properties of thecomplete circuit.
This should be considered as the most important part of the core due to its function ofcarrying the total flux generated by the winding. The centre post of ferrite cores is generallycircular (with or without a hole) or rectangular. If the centre post is circular, it is called centrepole and if the centre post is rectangular, it is called centre leg.
The main function of the outer legs is to guide the magnetic flux in a closed magnetic circuit.
The back has the same magnetic function as the outer legs; it can include wire-slots and wire-way areas (for example on RM-cores), the shapes and dimensions of which are dictated bythe winding and isolation requirements.
Besides accommodating clamping, the back surface (ground or not) serves as a referenceplane for grinding the mating surface to achieve its required parallelism，flatness andsmoothness.
The wire-slot area is the lateral area of the outer walls,interfacing with the cut-out portion.
The wire-way area is located on the bottom (inside) surface of the back, also called the floor.The wire-way runs radially from the centre post to the edge of the back wall, centred withrespect to the wire-slot areas.The purpose of the wire-way is to provide a path for leads toreach from the inside of the coil to terminals on the outside.
The clamping recess areas on the back accommodate clamping clips，affording securemounting,and preventing mechanical interference from the clip above the plane of the backsurface.
lrregularities such as chips，cracks and pull-outs should be compared to five simplegeometries which are shown in Table 1.
Such a table should be used as a reference for evaluation by operators either at the outgoingstage (core manufacturers) or at the incoming inspection (customers).BS EN IEC 63093-1 pdf download.