Variable Force Spring Design

Measure detent resistance and define the required spring force before, during and after engagement.

Integrate force over displacement through the actual working interval. Multiplying peak force by full stroke overestimates work for most changing curves.

State the held position, environment and dwell duration, then record first restart and the subsequent force profile.

The fixture and assembled mechanism can introduce rate-related resistance. A curve without speed is difficult to reproduce.

Mounting offsets can shift the curve relative to the mechanism’s working positions. Specify both part and assembly reference states.

The combined effects of profile change, friction and restart can be more visible there than during a continuous sweep.