Service order for products under Warranty

Hi all,

We want to create a Service order for products under Warranty and Non-Warranty.

So the main challenge we are facing while creating Service order and subsequent Sales order for Warranty products.

For Warranty products we don't want to charge anything to customer, so is it possible to create such a Service order and Sales order wherein nothing will be charged to customer but all the cost incurred while servicing the product should be debited to profit and loss account.

Any help will be appreciated.

Thanks

Prasad.