Can free supplies of material to recipient be considered as job-work?

X, a category of goods is made by P,Q and R. P & Q are purchased by supplier and R is supplied by recipient to supplier. This is not job work since job work is on goods belonging to another person. Whereas in this case P and Q are purchased by supplier. Substantial part of inputs belongs to principal in case of job-work. Moreover where supplier is paying tax on whole value of supply i.e. on value of X, there can’t be any inference of job work. This can be covered as part exchange. Refer Case Prestige Engineering India Ltd. v. Collector of Central Excise – 1994 (9) TMI 66 Supreme Court.