Special high temperature heat stabilization processes
Special edge chamfering
Epoxy coated
Special stack resistance requirements
Special part marking
Custom assemblies
Custom grinding & machining
Small Planar type geometries
Call for more details about these and other possibilities.
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 low excitation or low noise.
Mechanical 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, and
0.002
+0.062 max when B ≤ 2.000
+0.188 max when 2.000 < B ≤ 4.000
+0.375 max when B > 4.000
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
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
Width
All
-0.016 minimum
K = Cut Dimension
All
±0.062
R = Inside Window
Corner Radius
(Reference Only)
All
0.062 when F ≤ 2.000 and G ≤ 2.000
0.125 when F > 2.000 or G > 2.000
Maximum Core Tilt
All
0.031 when B < 3.500
0.062 when B ≥ 3.500
Note: A&B dimensions are held to maximum only. Negative tolerance for A & B are controlled by the F, G, & E dimensions. F&G dimensions are held to a minimum tolerance only. Positive tolerance for the F&G are controlled by the A, B & E dimensions.
Note: Nanocrystalline tolerances on D dimension are ± the stated positive tolerance to accommodate material shrinkage during the annealing process. Other tolerances may be different depending on geometry. Contact our engineering department for more details.
Customizable To Meet Your Needs
Custom sizes
Custom shapes
Multiple cuts
Special air gap cuts
Tighter tolerances
Low noise applications
Diamond-lapped mating surfaces
Special high temperature heat stabilization processes
Special edge chamfering
Epoxy coated
Special stack resistance requirements
Special part marking
Custom assemblies
Custom grinding & machining
Small Planar type geometries
Call for more details about these and other possibilities.
Standard Mechanical 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
.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, and
0.004
+0.094 max when A ≤ 5.000
+0.156 max when 5.000 < A ≤ 10.000
+0.250 max when A > 10.000
0.007
through
0.014
+0.125 max when A ≤ 5.000
+0.188 max when 5.000 < A ≤ 10.000
+0.312 max when A > 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)
All
0.062 when F ≤ 2.000 and G ≤ 2.000
0.125 when F > 2.000 or G > 2.000
Maximum Tilt
All
0.031 when F < 2.500
0.062 when F ≥ 2.500
Note: A&B dimensions are held to maximum only. Negative tolerance for A & B are controlled by the F, G, & 2E dimensions. F&G dimensions are held to a minimum tolerance only. Positive tolerance for the F&G are controlled by the A, B & 2E dimensions.
Customizable To Meet Your Needs
Cut in half
Diamond lapped if cut in half
Epoxy coated
Gapped to meet your inductance requirements
Air gapped for hall sensors
Chamfered ID & OD
Special stack resistance
Nylon & aluminum casedSmall Planar type geometries
Call for more details about these and other possibilities.
Standard Mechanical Tolerances for Uncased 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
Note: For unimpregnated cores, measurements will be made with core shaped into the most favorable position (minimum eccentricity), because these cores are often flexible.
Note: 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.
