Cylinder liners - Reconditioning of spare parts for power plant and marine diesel engines
Cylinder liners - Reconditioning in accordance to engine manufacturers recommendations
The cylinder liners of modern 4-stroke diesel engines are generally made out of alloyed cast iron – with lamellar graphite structure - casted by using the so-called centrifugal casting process.
Due to the relatively low dynamic stress and the almost static thermal stress, the cylinder liner is not among the highly stressed components in a diesel engine. Nevertheless, the cylinder liner fulfills an extremely important function. It leads the piston with its piston rings so that it can convert the combustion energy into kinetic energy.
To this end, the running surface of the cylinder liner must meet special tribological requirements. On the one hand, the friction of the piston rings should be as low as possible to minimize the engines internal friction losses. On the other hand, the running surface must be able to continously stock the lubricating oil, to avoid mixed- or even solid friction that can lead to piston seizures or piston jamming in the worst case. For this to work even sure, another important component is required - the lubricating oil. Amongst other things, the lubricating oil is to ensure that the tribological conditions for an undisturbed interaction between the cylinder liner, pistons and piston rings is most possible for thousands of hours.
But what properties are required of a high quality cylinder liner?
- Dimensional accuracy
- Dimensional stability
- Wear resistance
These properties are given due to the use of advanced casting and machining technologies. Nevertheless, after several thousand hours of running time, a cylinder liner must be checked in accordance to the engine manufacturers recommendation. The cylinder liners wear limit that he specified decides whether a liner can be reconditioned and used again or must be exchanged for a new one. No compromises should be made here.
An already worn cylinder liner may quickly affect other engine components resulting in serious engine damage finally.
An example therefore?
During normal engine operation, the piston continuously change his contact side against the wall of the cylinder liner. This movement (the contact side-change) is denoted as the piston secondary movement; briefly called KSB. This permanent side-change creates additional stresses into the piston skirt. FEM calculations and engine operation simulations, that have been carried out by us, are showing an additional load of 275 kN into the piston skirt, for an engine with a bore diameter > 450mm. Sounds like a lot ...? It is...
At this point it must be additionally noted, that this load has been calculated by us with an ideal clearance between piston skirt and cylinder liner wall. So we assumed new parts for both. Nevertheless, the reader of this article should not be worried about this. Until the specified wearlimit of a cylinder liner, the additional load from the KSB was part of the FEM calculation for every modern piston design. And simplified it can be stated: Each piston is structural durable until the cylinder liner is reaching his wear limits. Beyond the wear limit it's just a matter of time until the piston is damaged or – in worst case - decides to visit the crankshaft ...
And exact this is the reason why you should control your cylinder liners carefully and not to make any compromises or taking unnecessary risks. A cylinder liner that is just 1/10 mm within the wear limit yet, measured during a planned overhaul, is theoretically still in order, but will for sure not run over the next 6 to 8000 hours within the wear limit again.
We are happy to offer you the professional overhaul of your cylinder liners. In addition to the cleaning and crack detection, the rehoning of the cylinder liner in accordance to the manufacturer's instructions is for certain.
Sounds interesting? We are pleased to submit our offer to meet your requirements, ...just send us your inquiry.
MAN B&W
- MAN 23/30H
- MAN 23/30A-K
- MAN 27/38
- MAN 28/32H
- MAN 28/32S
- MAN 32/40
- MAN 32/40CD
- MAN 48/60A
- MAN 48/60B
Hyundai Himsen
- Himsen 25/33
Pielstick
- Pielstick PC2
- Pielstick PC2.5
- Pielstick PC2.6
SKL
- SKL NVD48
- SKL NVD48.2
Sulzer
- Sulzer ZA40S
- Sulzer Z40/48
MaK
Marine Motor Service GmbH
Cylinder liner reconditioning suitable for:
- MaK M25
- MaK M32
- MaK M43
- MaK M331
- MaK M332
- MaK M451AK
- MaK M452AK
- MaK M453AK
- MaK M453C
- MaK M551AK
- MaK M552AK
- MaK M552C
Wärtsilä
Marine Motor Service GmbH
Cylinder liner reconditioning suitable for:
- Wärtsilä VASA32
- Wärtsilä W32
- Wärtsilä W34SG
- Wärtsilä W34DF
- Wärtsilä W38A
- Wärtsilä W46A
- Wärtsilä W46B
- Wärtsilä W46C
- Wärtsilä W46D
- Wärtsilä W46GD