Welcome to the Xianghuai Website.We are mainly engaged in designing and manufacturing flexographic printing machines.

  Central Impression Drum Drum  construction in a central impression press can be of double-wall steel or cast iron. In either case the drum will be temperature-controlled by a heating/cooling device. As markets have advanced in flexography, and the product expected from a CI press has improved to high degree of excellence, press manufacturers have been compelled to hold more demanding tolerances in regard to the CI drum. Very commonly employed today is the use of digitally controlled heating/cooling elements, which hold drum temperature within a range of ±1°F. This close tolerance is a necessary element in the printing excellence being demanded of press manufacturers and converters today. If the press experiences variation in drum temperature, which causes CI drum size variation, the operator will be continually attempting to compensate, causing missed impressions or overimpression.

  The CI cylinder, independent of its method of construction, must be manufactured to meet high Total Indicated Runout (TIR) characteristics. It is very common today that specifications on a new press dictate that the drum not exceed 0.0003" TIR. Ideally, the drum will be held to a lower actual number if possible. Realizing that the TIR of the drum will only be as good as the supporting journal and bearings, manufactures of presses are demanding the use of printer-quality roller bearings with a TIR of around 0.0002". The use of custom hand-fit bronze bushings, which were very prevalent in the past, is losing favor with manufacturers today. The bronze bushings must be constantly lubricated, usually with a lube pump. The advantage of printer-quality roller bearings manufactured to acceptable tolerances is that they can be lubricated in a similar manner to gearbox (enclosed oil bath or grease pack).