Although injected zamak is not a big hit on google, zamak injections (processes) are, with around 45,000 hits, so I think it's fair to say that the inyectado is referring to the zamak.

http://64.233.183.104/search?q=cache:c4sLtIiBtUQJ:machinedes...

*Required strength normally dictates the metal used. Lead alloy is common in lightly loaded applications. However, most applications use Zamak 3 zinc alloy. While molten, this alloy easily can be injected into thin cross sections and intricate shapes while maintaining 41,000-psi tensile strength upon solidification. Higher strength requirements are met by Zamak 5, which provides 47,600 psi strength*