Frequently Asked Question

Dimensional and Surface Location Errors in CUTPRO.
Last Updated 3 months ago

When the tool and/or workpiece are flexible in peripheral milling, relative displacements occur between the two are imprinted on the surface finish, resulting in dimensional form or surface location errors. The errors are generated when the cutting edge is perpendicular to the finish surface. The displacements of the edge after leaving the normal surface are removed by the following tooth; hence they don’t affect the tolerance of the part. The helical edges leave periodic but saw teeth type of waves on the surface.

If the spindle rotates at low speeds, the form errors are generated mainly by the static deflection of the tool. If the spindle speed is high, the system either experiences forced (resonance) or chatter vibrations. Chatter leaves rough surface finish, while forced vibration leaves positive (down milling) or negative (up milling) offset on the surface finish. If such problems occur, the user needs to either avoid matching the tooth passing frequency (spindle speed times no of teeth) with the natural frequency of the system, or use zero helix and radial depth of cut which contains less than two teeth.

CUTPRO has been predicting the entire surface form since its inception in 1989. Unlike approximate solutions, CUTPRO milling module rotates/vibrates the tool while moving – vibrating the workpiece, which is the true kinematic model of milling. The chips are calculated by subtracting the digitized surface generated by one tooth by the previously generated surface, hence the surface errors, chips, forces, torque, power, vibration amplitudes are all calculated simultaneously most accurately.

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