Inter department movement in a manufacturing Industry

Hello,
I work in a Manf Industry as a Prod.manager.
Every time i get request from other supporting dept such as mainteannce, Warehouse facility to take people from production dept.
In our company there doesn't exist any HR policy?
Every time i suffer losses of skilled ppl migrating to other Depts.
Pls suggest how should i come out of this?
I am planning to recommend to my GM that there should be a HR policy defined?pls suggest?

More than Policy, what you need is Man-power Planning. You need to have clear understanding on the employee strength required in various functions and levels as well as where to locate them, internal or external. Maint., Ware house etc are ancillary to manufacturing areas and putting experienced people from mfg. area in these functions will be of immense help to Mfg. itself in the long run. So there is no need to feel bad if good guys from MFG are pushed to such ancillary jobs.