Grinding Contact Length Calculator

Inputs

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Current wheel diameter.
in
OD being ground, or the bore diameter for internal work (must exceed the wheel).
in
Radial wheel infeed per pass. Conventional finish passes commonly run in the 0.005-0.05 mm range.
in

Results

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Equivalent diameter(D_e)
1.714in
Pass

The single curvature the contact zone behaves as — bigger De = longer contact = harder-acting wheel.

Also computed

Contact length(l_c)0.0367in

Geometric arc of contact; real contact runs somewhat longer under deflection.

Contact ÷ depth(l_c/a_e)46.7

Method notes 4 notes
  • Curvature sum: 1/De = 1/ds ± 1/dw (+ external, − internal); a flat is the wheel alone. lc = √(ae·De) is the geometric value — elastic deflection stretches real contact somewhat longer.
  • Per-grit chip thickness falls as contact grows: the same wheel acts HARDER on internal work and SOFTER on small external diameters — the reason ID grinding picks softer grades than OD grinding of the same steel.
  • Burn risk tracks contact length at a given removal rate; when an OD recipe moves to a bore, drop the infeed or the wheel grade, not just the speed.
  • Kinematics only — grit, bond, dressing and coolant data come from the wheel maker; speeds live in the grinding wheel speed calculator.

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