Droplet Fragmentation
Secondary fluid masses created during the ejection of a primary drop from a nozzle represent an inefficiency in the printing process. This satellite drop formation occurs when the trailing tail of a liquid jet snaps off and forms smaller, independent spheres. Minor droplets lack the momentum of the main drop and often land off target.
The resulting spray creates a fine mist or haze around the edges of the intended design.
Tail Breakup
Surface tension acts to pull the elongated neck of a jetting fluid into a spherical shape. During satellite drop formation, the tail does not recombine with the main body before it impacts the fabric. Viscosity plays a dampening role by slowing down the contraction of the fluid filament.
Formulating inks with the correct viscoelastic properties minimizes the risk of these secondary particles forming.
Print Quality Impact
Stray ink on the textile surface reduces the overall contrast and blurs fine text or sharp lines. Because satellite drop formation is often erratic, it leads to inconsistent color density in solid areas. High speed printing exacerbates the problem by increasing the shear forces on the ink as it leaves the nozzle.
Maintenance routines must be more frequent when satellites contaminate the printhead faceplate.
Detection Method
Strobe photography and high speed imaging allow technicians to observe the jetting process in real time. Adjusting the voltage pulse or the temperature of the head can often eliminate the tails.
