hi kishoryy,
even i am working in a manufacturing company..in our comapny i have done a work on man power planning...the steps/process are as follows:-
1) Collect the data from every locations(only those locations where your company's other plants are located).
2) then try to complie it department wise and also plant wise
3) then try to tke out the age and numbr of experience that particular employee (management staff & operators) in your company has.
4) then see which employeee (includes both categories) are getting retired by the end of 2008-2009.
5) then try to see if u need any more people or you can trnasfer them from one department to another...or you can outsource your job(operators level) in case you want to reduce the manpower in your shop floor.
this is the way we have done in our company..
regards
ankit