You need formula parameters in work centers to:
You can define these standard values as you wish. The most common standard values are setup and machine time ("tr" or "te" according to REFA). In certain situations you must also define additional standard values, such as labor time and/or cleanout times.
Moreover, complex manufacturing processes require additional planning capabilities, such as calculation of energy or spatial requirements.
Key words describe formula parameters.
You should choose names for parameters that are easy to remember if you want to enter them in a formula definition later.