C-Cores
- Custom sizes
- Custom shapes
- Multiple Cuts
- Special air gap cuts
- Tighter tolerances
- Low noise applications
- Diamond-lapped mating surfaces
- Special edge chamfering
- Special high temperature heat stabilization processes
- Epoxy coating
- Special stack resistance requirements
- Special part marking
- Custom assemblies
- Custom grinding & machining
- Small Planar-type geometries
- Call for more details about these other possibilities
Dimensional Tolerances for Cut C-Cores per EIA Standard RS-217
| Core Dimension | Material Thickness (inches) | Allowable Tolerances (inches) |
| A = Outside Core Width | All | +0.031 max when A ≤ 1.500 +0.047 max when 1.500 < A ≤ 2.500 +0.062 max when 2.500 < A ≤ 3.500 +0.094 max when A > 3.500 |
| B = Outside Core Height | 0.0005, 0.001, 0.002 | +0.062 max when B ≤ 2.000 +0.188 max when 2.000 < B ≤ 4.000 +0.375 max when B > 4.00 |
| 0.004 through 0.014 | +0.062 max when B < 3.000 +0.156 max when 3.000 ≤ B ≤ 4.000 +0.188 max when 4.000 < B ≤ 6.000 +0.375 max when 6.000 < B ≤ 12.000 +0.438 max when B > 12.000 |
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| D = Core Strip Width | All * | +0.031, -0 when D ≤ 1.000 +0.047, -0 when 1.000 < D ≤ 2.812 +0.062, -0 when D > 2.812 +0.094, -0 when E > 2.500 |
| E = Core Leg Buildup | 0.0005 through 0.004 | ±0.016 when E ≤ 0.250 +0.031, -0.016 when 0.250 < E ≤ 1.000 ±0.031 when E > 1.000 |
| 0.007 through 0.014 | ±0.016 when E < 0.250 +0.031, -0.016 when 0.250 ≤ E < 0.562 ±0.031 when E ≥ 0.562 |
|
| F = Inside Window Width | All | -0.016 minimum |
| G = Inside Window Height | All | -0.016 minimum |
| K = Cut Dimension | All | G÷2 if G < 3.750, ± 0.062 1.687 if G ≥ 3.750, ±0.062 |
| R = Inside Window Corner Radius (Reference Only) | 0.0005 through 0.004 0.007 through 0.014 All All |
0.031 when F & G ≤ 2.000 0.062 when F & G ≤ 2.000 0.125 when F or G > 2.000 and F & G ≤ 5.000 0.156 when F > 5.000 |
| Maximum Core Tilt | All | 0.031 when B < 3.500 0.062 when B ≥ 3.500 |
| A & B dimensions are held to a maximum tolerance only, negative tolerances are controlled by the F, G, & E dimensions. F & G dimensions are held to a minimum tolerance only, positive tolerances are controlled by the A, B & E dimensions. * Nanocrystalline tolerance on the D dimension is ± the stated positive tolerance to accommodate material shrinkage during the annealing process. Other tolerances may be different depending on core geometry. Contact our engineering department for more details. |
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- MK Magnetics will gladly manufacture cores to your specific dimensional and physical requirements such as: non-standard mechanical tolerances, multiple cuts, or diamond lapped for lowest possible excitation and/or acoustical noise.
E-Cores
- Customizable to meet your needs
- NOTE: Please see “C-Cores” for all info
Dimensional Tolerances for Cut E-Cores
| Core Dimension | Material Thickness (inches) | Allowable Tolerances (inches) |
| A = Outside Core Width | 0.001 through 0.004 | +0.094 max when A ≤ 5.000 +0.188 max when 5.000 < A ≤ 10.000 +0.312 max when A > 10.000 |
| 0.007 through 0.014 | +0.125 max when A ≤ 5.000 +0.250 max when 5.000 < A ≤ 10.000 +0.375 max when A > 10.000 |
|
| B = Outside Core Height | 0.001, 0.002, 0.004 | +0.094 max when B ≤ 5.000 +0.156 max when 5.000 < B ≤ 10.000 +0.250 max when B > 10.000 |
| 0.007 through 0.014 | +0.125 max when B ≤ 5.000 +0.188 max when 5.000 < B ≤ 10.000 +0.312 max when B > 10.000 |
|
| D = Core Strip Width | All * | +0.031, -0 when D < 1.000 +0.047, -0 when 1.000 ≤ D < 2.000 +0.062, -0 when D ≥ 2.000 +0.156, -0 when 2E > 2.000 |
| 2E = Core Leg Buildup | All | ±0.031 when 2E ≤ 1.000 +0.062, -0.031 when 1.000 < 2E ≤ 2.000 ±0.062 when 2E > 2.000 |
| F = Inside Window Width | All | -0.016 minimum |
| G = Inside Window Height | All | -0.016 minimum |
| K = Cut Dimension | All | G ÷ 2.000, ± 0.062 |
| R = Inside Window Corner Radius (Reference Only) | 0.0005 through 0.004 0.007 through 0.014 All All |
0.031 when F & G ≤ 2.000 0.062 when F & G ≤ 2.000 0.125 when F or G > 2.000 and F & G ≤ 5.000 0.156 when F > 5.000 |
| Maximum Tilt | All | 0.031 when F < 3.500 0.062 when F ≥ 3.500 |
| A&B dimensions are held to a maximum tolerance only, negative tolerances are controlled by the F, G, & 2E dimensions. F&G dimensions are held to a minimum tolerance only, positive tolerances are controlled by the A, B & 2E dimensions. * Nanocrystalline tolerance on the D dimension is ± the stated positive tolerance to accommodate material shrinkage during the annealing process. Other tolerances may be different depending on core geometry. Contact our engineering department for more details. |
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Toroids
- Customizable to meet your needs
- Cut in half, 1/4’s, or 1/8’s
- Diamond lapped if cut in half
- Epoxy coated
- Matched sets 2, 3, 6
- Gapped to meet your inductance requirements
- Open airgaps for Hall sensors
- Chamfered or radiused ID & OD
- Special internal stack resistance requirements
- Nylon, Aluminum, and Phenolic cased
- Call for more details about these and other possibilities
Dimensional Tolerances for Toroids
| Core Dimension | Material Thickness (inches) | Allowable Tolerances (inches) |
| OD = Outside Core Width or Diameter | All | +0.031, -0.016 when OD ≤ 1.500 ±0.031 when 1.500 < OD ≤ 2.500 +0.062, -0.031 when 2.500 < OD ≤ 3.500 ±0.062 when 3.500 < OD ≤ 12.000 +0.125, -0.062 when 12.000 < OD ≤ 24.000 ±0.125 when OD > 24.000 |
| ID = Inside Core Width or Diameter | All | ±0.016 when ID ≤ 2.500 +0.031, -0.016 when 2.500 < ID ≤ 3.500 ±0.031 when 3.500 < ID ≤ 12.000 +0.062, -0.031 when 12.000 < ID ≤ 24.000 ±0.062 when ID > 24.000 |
| D = Core Strip Width | All * | +0.031, -0 when D ≤ 1.000 +0.047, -0 when 1.000 < D ≤ 2.812 +0.062, -0 when D > 2.812 |
| E = Core Buildup | All | ±0.016 when E ≤ 0.250 +0.031, -0.016 when 0.250 < E ≤ 1.000 ±0.031 when E > 1.000 |
| For unimpregnated cores, measurements will be made with core shaped into the most favorable position because these cores are often flexible. For epoxy coated (cased or encapsulated) cores add .0.040″ to the maximum “OD” and “D” dimensions, subtract 0.040″ from the minimum “ID” dimension. “E” dimension tolerance applies before coating only. * Nanocrystalline tolerance on the D dimension is ± the stated positive tolerance to accommodate material shrinkage during the annealing process. Other tolerances may be different depending on core geometry. Contact our engineering department for more details. |
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MK Magnetics will gladly manufacture cores to your specific dimensional and physical requirements such as: non-standard mechanical tolerances, multiple cuts, diamond lapped for lowest possible excitation and/or acoustical noise.
