When calculating takt time , how can we consider low volume , and high volume products on schedule with shared facility ?

I think, takt time remains the same as (available minutes for production)/(required units of production), whether for low or high volume.

But if one has to share resources -say there is one machine for a mix of different products- then there must be scheduling. Subsequently, takt time is calculated for each product based on the demand volume and the time allocated for that product.

In a shared-resource situation, if any of the takt time cannot be matched by the production capacity, one may be able to take available minutes from the other value stream(s) as the production rate may be different for each product. This way the schedule is updated and optimized. If there is still lack of available minutes, then one must resort to overtime or weekend shift.

Staggering the production is a possibility as there may be deadlines to met. However, machine setup would take away the available minutes. So one should plan accordingly.