Marine Diesel Engine Liner
05-06-2008, 06:17 AM,
#1
Marine Diesel Engine Liner
Hello, I'm new in this Forum and want to have an advise.


I have a customer that wants his Cylinder Liners and Pistons to be repaired.

I only have a Thermal Spray, Twin Wire Arc Spray. I need to know what is the material to be sprayed to the Liners and Pistons?

Please note that the material of the Liner is Cast Iron.

Liner, Piston Ring and Piston. In this three, I'm quite concern also for the issue of the dissimilar material that is involve in this job. If same material is sprayed to the liner and piston, there might be a possibility of seizure.


-Francis
Reply
05-09-2008, 09:41 AM,
#2
RE: Marine Diesel Engine Liner
mcg_pinsbushing Wrote:Hello, I'm new in this Forum and want to have an advise.


I have a customer that wants his Cylinder Liners and Pistons to be repaired.

I only have a Thermal Spray, Twin Wire Arc Spray. I need to know what is the material to be sprayed to the Liners and Pistons?

Please note that the material of the Liner is Cast Iron.

Liner, Piston Ring and Piston. In this three, I'm quite concern also for the issue of the dissimilar material that is involve in this job. If same material is sprayed to the liner and piston, there might be a possibility of seizure.


-Francis

hello
you will try WC 10Co 4Cr
size -45+15
I think it will do it
good luck
Reply
05-10-2008, 01:30 PM,
#3
RE: Marine Diesel Engine Liner
Hi Francis

Sign0016 to the Surface Engineering Forum.

I would consider 13Cr steel or a 1%C steel for cylinder liners.

What is the piston material and is it just the skirt that needs repair?

Piston rings would ideally be molybdenum coated.
Reply
05-10-2008, 01:54 PM,
#4
RE: Marine Diesel Engine Liner
Hi Gordon,


Thank you for your email.

Thanks for welcoming me.


Yes I understand because Chrome Carbide-Nickel Chrome and 95 MXC is very hard and honing these is not impossible but very expensive.

So 420 Stainless Steel is the alternative choice. What do you mean about 1%C steel,? What type of material is that?

What is the piston material and is it just the skirt that needs repair?

Both the Cylinder Liner and Piston is Cast Iron. The entire piston will be sprayed and after that we will cylinder grind it.


-Francis
Reply
05-10-2008, 02:19 PM,
#5
RE: Marine Diesel Engine Liner
Hi Francis
Quote:What do you mean about 1%C steel
A plain steel with around 1% carbon content (like Metco Sprasteel 80AW wire).

For the piston I think molybdenum would be good.
Reply
05-10-2008, 02:36 PM,
#6
RE: Marine Diesel Engine Liner
Hi Gordon,


Thank you for your email.

First I would like to know, if 420 Stainless Steel is for high temperature use? About how many degrees Celsius would you think its maximum operating temperature would be?

Please note that the Combustion Camber of the Marine Diesel Engine is subjected to high temperature.

For the Cylinder Liner, I have seen in Durum (Germany) DURMAT AS-888 and AS-890, in which the two of them can resist temperature about 870 degrees Celsius. And having a hardness of 45 HRC which can easily be Honed.

Durmat AS890 Is equivalent to 90MXC (Tafa). These wires is capable of increasing its hardness after prolong use.

Will these materials be okay? I have not tried them yet.


-Francis
Reply
05-10-2008, 02:58 PM,
#7
RE: Marine Diesel Engine Liner
Hi Francis

Quote:First I would like to know, if 420 Stainless Steel is for high temperature use? About how many degrees Celsius would you think its maximum operating temperature would be?
I think 420 Stainless Steel and most of the coatings mentioned should be ok. After all the original cast iron I assume worked fairly well. With cooling and lubricating oils the coating temperatures should be well below that of the combustion gases.

Quote:For the Cylinder Liner, I have seen in Durum (Germany) DURMAT AS-888 and AS-890, in which the two of them can resist temperature about 870 degrees Celsius. And having a hardness of 45 HRC which can easily be Honed.

Durmat AS890 Is equivalent to 90MXC (Tafa). These wires is capable of increasing its hardness after prolong use.

Will these materials be okay? I have not tried them yet.
No experience on this, but I would expect them to work well although possibly a little over the top Big Grin
Reply
05-10-2008, 03:11 PM,
#8
RE: Marine Diesel Engine Liner
Hi Gordon,


Thank you for your advise but one last thing. You mentioned: "Piston rings would ideally be molybdenum coated". I know this because I can see that on all catalogs of the thermal spray wires manufacturers.

But how can you be able to machine the Piston Rings after it is been coated with Molybdenum?

I think it's a little bit difficult to mount it in the lathe machine.


-Francis
Reply
05-10-2008, 04:35 PM,
#9
RE: Marine Diesel Engine Liner
Hi Francis

I think most piston rings are processed by loading multiple rings onto a mandrel, where they are pre-ground, grit blasted, thermally sprayed and then finished ground. Coating is normally recessed into piston ring face like https://www.gordonengland.co.uk/pmg16.htm
Reply
05-15-2008, 08:33 AM,
#10
RE: Marine Diesel Engine Liner
Gordon Wrote:Hi Francis

I think most piston rings are processed by loading multiple rings onto a mandrel, where they are pre-ground, grit blasted, thermally sprayed and then finished ground. Coating is normally recessed into piston ring face like https://www.gordonengland.co.uk/pmg16.htm
Reply
05-15-2008, 10:48 AM,
#11
RE: Marine Diesel Engine Liner
Hi DYNA

Sign0016 to the Surface Engineering Forum.

Are you having problems with your post? Remember that you can "Preview Post" and edit as much as you like before "Post Reply". Once posted you can still go back and edit Big Grin
Reply
05-15-2008, 12:46 PM,
#12
RE: Marine Diesel Engine Liner
Gordon Wrote:Hi DYNA

Sign0016 to the Surface Engineering Forum.

Are you having problems with your post? Remember that you can "Preview Post" and edit as much as you like before "Post Reply". Once posted you can still go back and edit Big Grin


Hi Gordon,
as you see I am new at this Forum.
My reply was about marine diesel engines piston crowns reconditioning. I am working 38 years for low speed marine diesel engines factory, last 3 years as reconditioning manager.
Piston crowns has generally grooves rings oversized, also piston crown botton is burned. In this case any metal sparying technology is not sufficient. Grooves section has to be remooved by turning, then rewelded with proper material. The best way for this is SAW technology. Of course piston crown has to be preheated before. After rewelding annealing is required. Next - machining according to original diamensions and grooves chromium plating. In this case piston crown is real equivalent for th enew one.
About cylinder liners - main problem is the oil deposit inside cast iron. After long sevice cast iron is as "foam" with the oil, so only long carefull preheating removin oli from the material. Of course defetting and grit blasting is obligatory. The best technology is flame powder coating - MoNiSF powder, the gun cost is about 3500�.
Note: for main engine parts Classification Societies approval is required. Unfortunately till now LLoyd's, DNV, GL are not interested specially in reconditioning technologies.
Thomas
Reply
05-16-2008, 05:00 PM,
#13
RE: Marine Diesel Engine Liner
Some sound advice I think. Thanks Thomas Cheers
Reply




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