No aadhar is not mandatory to generate uan, you can generate uan without aadhar but for benefit of employees later on you have to do kyc- aadhar,bank account no etc.
Even pf authority provided non aadhar form also to withdraw benefits.
For esic, aadhar is compulsory as they are doing treatment only on basis of aadhar. Esic has stopped bio metric pehchan & now they are not providing esic cards in delhi- & later- on they will stop it every location too so please suggest your employees to make theier aadhar asap.
Regards
nishu#