Home

MK Magnetics Core Tolerances
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.
    		•

    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.
    home | news | products | about us | contact
    MK MAGNETICS INC • 17030 Muskrat Avenue, Adelanto, CA 92302
    760.246.6373 • 800.605.9565 • FAX 760.246.6378 • www. mkmagnetics.com • info@mkmagnetics.com
    Copyright © MK Magnetics, Inc. All rights reserved. • www.mkmagnetics.com