there is general increase in the density from titanium to zinc why?

There is a general increase in density from Titanium to copper not upto zinc.
Since the shielding effect of d electrons is less ,therefore there is a gradual increase in attraction from nucleus and decrease in metallic radii.
This decrease in metallic radii causes decrease in size of an atom from Ti to Cu.
Since density = mass per unit volume and with decrease in size volume of atom decreases and  thus density increases.