Materials and Stock

Some material characteristics to consider when selecting candidates:

• Magnets

  • Required strength (ferrite, neodymium, samarium-cobalt)

  • Acceptable losses (eddy currents)

  • Stock shape availability (bar, ring, arc, etc.)

  • Compatible pre- and post-processing (electrical conductivity for EDM, brittleness for machining)

  • Risk of demagnetization loading (localized heat, mechanical shock, etc.)

  • Supply chain import sensitivity (rare earth metals vs ferrite)

  • Protective coatings

• • Spur (cost-effective option suited for low speeds, loads, and high noise level)

    • Simple

    • Common

    • Can be made using wire EDM

    • Shorter life due to large instantaneous loading

    • Imprecise (large backlash from single engaged tooth)

• • • Helical (budget option for higher speeds, low-medium loads, and low noise)

      • Moderate

      • Quieter operation from gradual engagement

      • Smooth power transmission (multiple teeth engaged)

      • Unbalanced loading requires thrust bearing to secure in place

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• • • Herringbone (higher performing option for higher speeds, medium-high loads, and low noise)

      • Complex to produce

      • Smooth power transmission (multiple teeth engaged)

      • Symmetric tooth design yields balanced loading, no thrust bearing needed

• • • • Bevel

        • Compact

        • Angular transmission of torque

        • More difficult to produce

        • Can be combined with the above tooth patterns

• • • • Worm (suited for compact, high torque applications)

        • Compact

        • Angular transmission of torque

        • Transmits very large torques

        • High energy losses (due to large contact area)

• • • • Rack and pinion

        • Convenient conversion of rotational to linear motion in the same plane

        • Precise control

• • • • Harmonic gearing

        • Flexible gear ring deformed by rotating cam inside static ring

        • Unequal numbers of teeth to control angular advance per rotation

        • No backlash

        • Compact