Esi & pf liability in case of job work out side premises

principal employer is a registered with ESPF act. Principal employer sends raw material to outside factory ( company or partnership firm or sole proprietorship) to convert form of the raw material (basically job work like injection moulding or powder coating or plating). the outside factories may or may not be covered under PF or ESI as they are independant entity. please suggest, is the principal employer company must deduct pf & esi from the job work charges bills submitted. sanjiv