Core Gapping

Dexter offers the ability to provide custom gapped and machined ferrite cores. Dexter stocks a large inventory of manufacturer “standard” gapped cores as well as ungapped ferrite cores from various manufacturers including Magnetics, Inc, Ferroxcube, EPCOS/TDK, Fair-Rite Products and more.

We understand that our customers may need ferrite core gapping and machining services to achieve AL values that aren’t readily available direct from the manufacturer. Our experienced machinists can custom gap cores to an inductance (or AL value) or to a dimensional specification. In doing so, Dexter relieves the high minimum order quantities and extended factory lead times from the manufacturer.

Gapping to an electrical inductance or AL value requires the use of a test coil to guarantee accuracy. Typically tested using a “decade” (multiple of ten) test coil, the proper frequency and voltage levels drive the core to the proper flux level. Alternatively, customer supplied test coils will give exacting accuracy for the end use. AL gaps are typically held to +/-1%
Gapping to a mechanical dimension is very straightforward and tolerances can typically be held to +/-0.001″

Dexter uses a cell manufacturing process to adjust its manufacturing capacity to meet customer demand. Typical lead times are 2 weeks or less. Urgent demands, small runs and prototypes, are often provided in 1 week or less.

Dexter prefers to work with our stock product offerings for gapping, however, if a customer needs their own material gapped, Dexter can receive material in and gap to the same process as if the material were our own.

When an application goes into higher volumes, Dexter will work with the you and manufacturer to develop the proper stocking package to meet your on time delivery needs.

As noted above, gapping can be done either to a physical dimension or a specified AL value and tolerance, but not both. Dexter has developed methodology to properly call out gapping to avoid confusion.

These methods are

Method 1 – gap ONE PIECE of a pair to a physical dimension
Method 2 – gap ALL PIECES to a physical dimension
Method 3 – gap ONE PIECE of a pair to an AL when matched with an ungapped core
Method 4 – gap ALL PIECES of a pair to an AL when matched to an ungapped core
Method 5 – gap ALL PIECES symmetrically to an AL value
Method 6 – gap ALL PIECES symmetrically to a physical dimension