Paper Machine Dryer Inspection : Part I - Metallurgy of Cast Iron and Inspection of Heads and Journals, 1997 Engineering Conference Proceedings
Many paper machine dryer failures result from fatigue of heads and journals which originate due to casting flaws or poor quality castings. This paper reviews differences in gray cast iron metallurgy between “old” and “modern-day” dryer castings. The influence of cast iron structure and flake morphology on mechanical and physical properties, including fatigue strength and sonic velocity is reviewed.
Today, in-service dryers are routinely tested for surface flaws using the magnetic particle method. These inspections have revealed new problems because significant flaws must be evaluated to determine if they are propagating or benign. Methods of in-service evaluation of flaws, including in-place metallography are discussed. Examples are given of fatigue failures which have occurred in dryer heads and journals after long periods of operation.
Paper Machine Dryer Inspection : Part I - Metallurgy of Cast Iron and Inspection of Heads and Journ
