Excise duty implications on job work charges

Dear Professionals

What are the excise duty implications on job work charges.

If an SSI unit does job work for another SSI unit exempt of Excise duty upto Rs.1.5 crores, does the SSI unit who performs job work needs to pay excise duty on the job work done.

Eg: If Company "A" an SSI unit performs job work for Company "B" an SSI unit, does company "A" needs to pay excise duty on the job work done towards Company "B"?

Please advice and provide your sugesstions.

Regards

Deepak