yutaini, I take it your talking about a U/S parts washer. In terms of temperature, surfactant conc., energy input and frequency changes. These all are dependent on the type of "dirt" that's adhering to the part. It would probably be best if you contacted the manufacturer of the equipment. They in all probability have extensive experience/knowledge and know the best methods for optimizing the system by manipulating the above.
Hope this helps.
saxon