An exemplary embodiment of the invention provides a method of direct chill casting a composite metal ingot. The charging unit includes a pair of mounting members, a discharging electrode filament, a shield casing, a grid, and a connecting member. The protrusions preferably cover a majority of the outer surface of the pet toy. The insulating layer includes a flange that abuts against an inner face of an inner frame during a procedure for forming a housing of a plug, thereby preventing moisture from entering an interior of the housing of the plug. Method includes heating andor accelerating a gas to form an effluent gas stream, feeding a particulate-bearing carrier stream through an axial injection port into the effluent gas stream to form a mixed stream, in which the axial injection port includes a plurality of chevrons located at a distal end of said axial injection port, and impacting the mixed stream on a substrate to form a coating.