Helical gears will remain an essential element in mechanical engineering world. They work efficiently during their working lifetime. During this time wear progresses affecting the efficiency of functioning. Even sudden failure may result at any time. So, immediate replacement is a must in all cases. Although, helical gears are standard and being machined with standard cutters having standard modules, but nowadays all the profiles of the gears are being modified during machining for multi reasons. Some modifications are needed to avoid tip or root interferences. Some are needed to adjust the center distance of the mating gears to meet the pre-designed value in the assembly box. Others may be to re-strengthen the tooth to stand heavier loads. Some of the parameter needed for manufacturing can be obtained directly through the use of metrological equipment but modification parameters can’t be measured. So, it has to be deduced by trial-and-error procedure. The procedure results in providing several alternatives, which requires further work to decide on the optimal solution. This paper works on determining the optimal value of the addendum modification. It is done by studying the stress variation along the tooth, the deflection of the tooth under load and the resulting strain due to the change in the addendum modification. Model for presenting the tooth profile with modification is given.

helical gears, addendum modifications, Modified tooth profile