Cast Iron Engine Block Nitriding

[chadzeilenga]

Hello all,
I am planning the buildup of a Ford 390 FE engine for street cruising and occasional strip use in my 1966 Galaxie 500XL. This engine will not be built until next winter, but I am trying to plan as much of it out as I can now so I don't run into too many problems when the time comes.

My question is regarding Ion Nitriding. I have heard about this process briefly before regarding it's use on engine blocks, crankshafts & connecting rods as a way to increase the surface hardness of them. This months AM&P mag has a good article regarding the history and how this process works. I am investigating having this work done on my engine to increase the durability of it.

Does the Ion Nitriding process change the physical dimensions of the part being nitrided? Is there any growth (depending on material) seen when this process is done? I will be purchasing a used 390 engine block and a new cast steel crankshaft for this engine and would like to have these nitrided to increase their strength. If the engine block was nitrided would this be done before or after all of the machining operations (bore & hone cylinders, align hone crank journals?

I am planning on having the corners of the journals on the crankshaft radiused as this is a common process to reduce the stress risers that occur there and am also planning on having the journals micropolished. I am assuming that if I have the nitriding done this will all be after the final machining operations so that the "case" depth will not be reduced and that machining the hardened surface will be difficult and time intensive.

Please offer any advice which you might have regarding this topic.

Thanks,
Chad Zeilenga
SealMaster Bearings
Co-op Engineer

 

[swall]

I can't see the wisdom in nitriding an engine block. Perhaps you heard about nitrided cylinder sleeves and interpreted that to mean the entire block was nitrided? Ion nitriding would be especially difficult, as most ion nitride chambers are not big enough.Also, ion nitriding is a "line of sight" process, which means that getting a uniform nitride layer in the bore would be problematical.

 

[chadzeilenga]

Swall,
I guess that I have only heard of Ion Nitrided cylinder sleeves. The purpose which I was seeking for nitriding the engine block would be to reduce the cylinder wall wear as the block is very strong originally. What do you mean by "line of sight" process?

Chad

 

[swall]

By "line of sight", I meant that it is not a conformal process, i.e. the nitride will not nicely conform to all of the part contours. Think of spray painting--a cloud of paint envelopes the block and some goes down into the bore.Then think of dipping a block in a vat of paint.Every surface gets covered with a uniform layer.

 

[ubrales]

Chad, I have done Nitriding on Inserts for Die Casting Dies and have some of the answers:

1. Nitriding may be done only after all machining operations such as grinding, lapping, polishing, etc. are completed. The nitrided case becomes glass hard, very brittle and is approx. Rockwell C 70.

2. No operations can be done after nitriding.

3. There willl be a slight (0.1%) growth after nitriding.

Regarding your application - nitrided surfaces do not hold lubricant very well. The nitrided case is very brittle. Will these be problems? Also, take into consideration the materials and functions of the mating parts.

 

[76GMC1500]

Nitriding cranks is standard practice and is done by virtually all auto manufacturers today. I've never heard of anybody nitriding a cylinder. Woudl it create problems during the break-in because it is harder than the piston rings? Many motorcylcles (especially 2 strokes) have nickel plated cylinders. The trend now is nikasil.

 

[patprimmer]

There is a company in Melbourne Australia who was setting up to Nikasil coat the bores in V8 engines. He should be in operation by now if it went according to plan. The cost was expected to be about A$2500, finished to size and honed, ready to run. Yes they can do it on cast iron.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[EngJW]

Continental aircraft engines have nitrided cylinder barrels. Since they are thin wall, they are made of steel for strength. Steel is not as good a mating material for piston rings as gray cast iron, so that might be why the nitriding is used. Chrome plating is also used in steel barrels, and there is a company in Texas that does Cermichrome which I think is something like a Nikasil.

John Woodward

 

[willeng]

Pat:

Would you have the name of the place in Melbourne that is setting up for Nikasil coating.

chadzeilenga:

Your best bet might be to have the block cryo-aged then nikasil coat the bores, this will help.

 

[patprimmer]

John

They are:-
LM Electroplating Industries
7 George Circuit
BRIAR HILL Vic 3088
Australia

Phone: 61 3 9435 7029
Fax: 61 3 9432 1995

http://www.electrosil.com.au

They actually call their process "Electrosil" as Nikasil is registered and requires an expensive licence.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[patprimmer]

Sorry

My last post should have been addressed to willeng, not John

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[willeng]

Thanks Terry?

 

[patprimmer]

No problem Fred

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[chadzeilenga]

To all,
Thanks for the info, I think I am going to only get the crankshaft nitrided, as it is going to be new.

Chad