Consider a batch process with two stations. Each station can handle a batch size of up to $100$ units. Station $1$ has a processing time of $2$ minutes per unit, and no setup time. Station $2$ has a setup time of $20$ minutes per batch, and a processing time of $1$ minute per unit. Processing units for a batch in Station $2$ may only start when all the units in the same batch have been processed in Station $1.$ In contrast, set up for a batch in Station $2$ may being before that time.