Abstract: A lightweight, thin walled, plural metal coated plastic sleeve for use in rotogravure or flexographic printing as well as a rotogravure printing cylinder are disclosed. The sleeve is supported internally and laterally by, for example, an expanding mandrel containing journal bearings and the resulting combination may be used as a rotogravure printing cylinder in a rotogravure printing machine. The sleeve and cylinder are lightweight and easy to handle and store and are adapted for quick changes in the printing machine without removal of the journals and the internal support. The particular method of making the sleeve enhances the adhesion of the copper to the plastic base.

Abstract: A coating of wear resistant tungsten carbide is applied to a photo-etched roto-gravure cylinder, the coating having a thickness in the range of from 15 to 35 microns. Tungsten carbide powder is supplied to a plasma flame spray gun by means of a powder feeder which supplies powder particles at a uniform density and at given sizes. The feeder comprises a hopper having air inlet and outlet passages and vertically spaced porous membranes which confine the powder and permit the passage of air. Air flow through the hopper suspends the powder particles of a desired diameter range adjacent a spray gun feed conduit. When copper cylinders are to be coated, the surface is allowed to oxidize to promote a chemical bonding of the coating to the surface.

Abstract: A coating of wear resistant tungsten carbide is applied to a photo-etched roto-gravure cylinder, the coating having a thickness in the range of from 15 to 35 microns. Tungsten carbide powder is supplied to a plasma flame spray gun by means of a powder feeder which supplies powder particles at a uniform density and at given sizes. The feeder comprises a hopper having air inlet and outlet passages and vertically spaced porous membranes which confine the powder and permit the passage of air. Air flow through the hopper suspends the powder particles of a desired diameter range adjacent a spray gun feed conduit. When copper cylinders are to be coated, the surface is allowed to oxidize to promote a chemical bonding of the coating to the surface.