You can't include units in a value from a component. Components just don't interface with Mathcad's unit handling. Usually you just add units subsequently. But there is no need to define conversion factors. The "units" in Mathcad are just variables that contain the value of the unit, exactly what you want as a conversion from just the measure (in that unit) to a proper value. Hence if you output a value that is a number of millimeters to a variable called test, you can simply update test by test:=test*mm. If the units are not completely fixed by the logic of the program but are specified in the Excel worksheet, the problem is more complicated. For that you should visit the collaboratory and look up my define variables work sheet, or, for a sample implementation, the AISC steel shapes work sheet.
