Page 38 - 2022 - Q4 - Minerva in Focus

MARINE TECHNOLOGY Cylinder honing: workshop capabilities
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Cylinder lubrication is crucial for proper
engine operation, ensuring a good per- and hit marks. In such cases, honing using depend on the case and target set by the
special cutting diamond stones can remove
customer, along with our experts’ guidance.
formance and long working life of major damaged material and save the liner from The rougher the starting surface finish is,
engine components such as pistons and scrapping. At Injegov, we perform honing the more material removal will be needed
liners. using our Chris marine honing machines on- to achieve the best finish possible.
board and at our dedicated honing rigs.
Honing has to do with how - scrubbing with Is cylinder honing necessary?
abrasive (as opposed to an operation that Common misconceptions regarding cylinder
produces chips), of which common objec- liner honing When replacing piston rings with new ones,
tives include getting a specific finish or very it is always preferable to restore the liner
finely toleranced geometry. Owners should be aware, though, of some surface by honing! Honing creates small
During routine maintenance, besides cali- common misconceptions regarding cylinder pockets on the liner surface, trapping oil
bration of cylinder liner diameter and visual liner honing: and ensuring proper cylinder lubrication.
inspection of liner surface, honing patterns, • 1st, The honing method is not the same
liner surface quality, and roughness should for all liners of all makers. Different So, do I need new rings after honing?
be carefully examined and, if needed, re- liners require different roughness and
stored. The quality of the liner surface is cru- honing patterns which in turn require Yes, the new rings need a freshly honed
cial for the even distribution of lubrication oil using different honing stones and arms. surface to bed in, even if the original honing
and the proper operation of the piston rings. • 2nd, Honing stones and tools must be pattern is visible. The honing pattern holds
To produce state-of-the-art surface finishes kept in good condition as they directly vital oil for the ring; it lubricates, cools, and
without compromising productivity, a multi- affect the quality of the honing pro- removes wear particles.
step honing process, combining rough hon- cedure. Damaged grinding stones or
ing with peak or plateau honing, is used. The improper tool operation will result in
honing process’s outcome depends on many substandard results.
parameters, including the machine type, • 3rd, Honing is not machining! Although
working conditions, tools, process fluid, and, honing can remove material and sur-
most importantly, the operator experience. face damage (especially when using
Honing is the method recommended by diamond stones) and can marginally
engine makers for restoring liner surfaces. At improve overall liner geometry, honing
the honing rigs in our workshops in Piraeus cannot completely remove ovality from
and Tuzla or onboard the vessels, we make liners!
sure to perform honing using the right honing
stones each time to achieve the suggested How much does honing remove from the
roughness values and honing pattern. cylinder?
Besides restoring the surface quality, honing
of liners can also be used to repair liners con- When honing (abrasive flow machining), the
taminated with cat fines that have suffered amount of material removal can be con-
scuffing, corrosion damages, or scratches trolled to remove as little as 002” and will

by Antonis Kalampokas,
INJEGOV SA Honing operation on a MAN B&W Cylinder liner Liner internal diameter surface after honing

38 MINERVA IN FOCUS – ISSUE 22 / Q4 2022