WORKSHOP MANUAL W26 Wärtsilä NSD Nederland B.V. Engine type W26
Chapter 2.5
Subject Engine block/Cylinder liner
Issue date June '00
Cylinder liner reconditioning 1 Material ; Material: GG 30 (Centrifugally cast) 2 Honing quality criteria; 2.1 Uniformity of the honing appearance The overall appearance of the cylinder wall should be clear, uniform and clean. 2.2 Formation of honing scores. Cut edges clean and sharp, with scores uniform. 2.3 Orientation of honing scores Uniform cutting during the upward and downward strokes. 2.4 Honing profile Sharply cut, edges not turned down and smeared over, see fig 3.
3 Hone machining: Whenever new piston rings are mounted, the cylinder liner must be honed by means of “ plateau honing “ -
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If the machining is done in the engine block, honing debris / coolant must be prevented from falling into the sump. Use a fair amount of clean gas oil as coolant, and to flush away the grains. During honing the stones should not leave the liner surface for more than max. 2 - 3 cm length. Clean hone stones regularly ( every 2 - 3 minutes ) by rubbing another hone stone over the running surface of the hone stone to prevent smearing of the honing profile. The up- and down speed in combination with the rotation speed of the honing machine determines the honing groove cross angle. The coarseness of the stone in combination with the contact pressure against the liner wall and the duration of hone machining determines the amount of material that is removed and the roughness of the hone groove created. Use ceramic hones with a coarseness of 100 to roughen the surface. (in case of scoring marks, removal of ovulate etc. diamond stones can be used for pre-machining ) .When roughening, try to remove as little material as possible. Therefore a “divergent shaped” liner is allowed ( see no-go sizes ). In the upper region of the liner extra machining has to be carried out, as the liner is mainly worn in this region.
Therefore hone after each full stroke alternately, the top part of the liner bore (over a height of approx. 20 cm)
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