Flattening irons back into spec?
06-22-11, 02:01 PM
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Flattening irons back into spec?
I have some irons for my turbo 2 which are a little out of the flatness spec. I was told buy a friend who owns a machine shop that he could probably just mill them flat again and clean them up with flatness grinders. Is this an acceptable way to fix them? Not much metal would be taken off, it is removing about .003 of metal to get a step worn into the combustion side of the iron out. All 3 irons have similar wear.
What do you guys recomend?
What do you guys recomend?
06-22-11, 02:35 PM
#3
i would also recommend lapping versus a surface grinding, because surface grinding is not an even cut and will take off more material from some areas than others varied from the original true flat origination surface.
lapping is recommended because the nitrite layer is only about .015" thick.
.003 is not a specification so i assume he meant .030" which is well beyond the nitrite layer. if you need to take off .030 to get a it back within spec then the irons are either junk or need to be nitrited again, in most cases lapping and nitriting cost about $150-200 per iron.
lapping is recommended because the nitrite layer is only about .015" thick.
.003 is not a specification so i assume he meant .030" which is well beyond the nitrite layer. if you need to take off .030 to get a it back within spec then the irons are either junk or need to be nitrited again, in most cases lapping and nitriting cost about $150-200 per iron.
06-22-11, 03:17 PM
#5
i would also recommend lapping versus a surface grinding, because surface grinding is not an even cut and will take off more material from some areas than others varied from the original true flat origination surface.
lapping is recommended because the nitrite layer is only about .015" thick.
.003 is not a specification so i assume he meant .030" which is well beyond the nitrite layer. if you need to take off .030 to get a it back within spec then the irons are either junk or need to be nitrited again, in most cases lapping and nitriting cost about $150-200 per iron.
lapping is recommended because the nitrite layer is only about .015" thick.
.003 is not a specification so i assume he meant .030" which is well beyond the nitrite layer. if you need to take off .030 to get a it back within spec then the irons are either junk or need to be nitrited again, in most cases lapping and nitriting cost about $150-200 per iron.
06-22-11, 04:12 PM
#7
that is less than i have found from researching on other nitriting measurements, basically the nitriting layer is already burned through on almost all irons with ~70k or more miles then. i still haven't noticed severe wear from lapping irons beyond that .004" figure though.
nitriting was introduced with the later model 13B engines(FC and beyond), early model 12A and prior engines were just milled cast iron and had a tendency to have about twice the wear of the later model engines with the same mileage. i wonder if nickelsil would be an alternative, of course we have neither in vegas. there are facilities in various places who can do either but only a few that can do both lapping and treating, i only do lapping.
keep in mind this was something new when it was introduced so Mazda's nitriting process may be inferior to today's standards.
nitriting was introduced with the later model 13B engines(FC and beyond), early model 12A and prior engines were just milled cast iron and had a tendency to have about twice the wear of the later model engines with the same mileage. i wonder if nickelsil would be an alternative, of course we have neither in vegas. there are facilities in various places who can do either but only a few that can do both lapping and treating, i only do lapping.
keep in mind this was something new when it was introduced so Mazda's nitriting process may be inferior to today's standards.
Last edited by RotaryEvolution; 06-22-11 at 04:17 PM.
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06-22-11, 04:57 PM
#8
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Originally Posted by Karack
because surface grinding is not an even cut and will take off more material from some areas than others varied from the original true flat origination surface.
The trick with the irons is the hard nitrite surface is difficult to surface grind without getting too much heat into the work. Even using coolant. One really has to know his stuff to get good results. The heat can cause the metal to expand and bow up into the wheel causing low spots.
I used a 36 grit "H" hardness wheel (14" x 2") and coolant. It was a bitch. You will have to constantly dress the wheel because the nitrided iron plays hell with it. One has to watch for plate warpage and shimming of the first side down might be needed. That or a variable magnet. Of course, a good stoning on the first side down is a must.
Last edited by TonyD89; 06-22-11 at 05:01 PM.
06-22-11, 05:01 PM
#9
correction, i did find a shop locally who does nitriding after some digging and called for estimates.
keep in mind this is an oven that charges by the hour whether it has 3 irons in it or 20(maximum capacity for a small oven). a full day of baking is $700-800. so if i can get 20 irons together then the process is ~$40 per iron or if i only have 1 set of 3 irons to be baked it is ~$250 per iron.
i think you just proved my point.
keep in mind this is an oven that charges by the hour whether it has 3 irons in it or 20(maximum capacity for a small oven). a full day of baking is $700-800. so if i can get 20 irons together then the process is ~$40 per iron or if i only have 1 set of 3 irons to be baked it is ~$250 per iron.
This is not true. Surface grinding is very accurate and will leave you an almost perfectly flat and smooth surface. Most likely, too smooth for oil retention. Some sort of additional surface prep would be necessary (before re-nitriding).
The trick with the irons is the hard nitrite surface is difficult to surface grind without getting too much heat into the work. Even using coolant. One really has to know his stuff to get good results. The heat can cause the metal to expand and bow up into the wheel causing low spots.
I used a 36 grit "H" hardness wheel (14" x 2") and coolant. It was a bitch. You will have to constantly dress the wheel because the nitrided iron plays hell with it. One has to watch for plate warpage and shimming of the first side down might be needed. That or a variable magnet. Of course, a good stoning on the first side down is a must.
The trick with the irons is the hard nitrite surface is difficult to surface grind without getting too much heat into the work. Even using coolant. One really has to know his stuff to get good results. The heat can cause the metal to expand and bow up into the wheel causing low spots.
I used a 36 grit "H" hardness wheel (14" x 2") and coolant. It was a bitch. You will have to constantly dress the wheel because the nitrided iron plays hell with it. One has to watch for plate warpage and shimming of the first side down might be needed. That or a variable magnet. Of course, a good stoning on the first side down is a must.
Last edited by RotaryEvolution; 06-22-11 at 05:03 PM.
06-24-11, 01:57 PM
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06-24-11, 04:29 PM
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i would also recommend lapping versus a surface grinding, because surface grinding is not an even cut and will take off more material from some areas than others varied from the original true flat origination surface.
lapping is recommended because the nitrite layer is only about .015" thick.
.003 is not a specification so i assume he meant .030" which is well beyond the nitrite layer. if you need to take off .030 to get a it back within spec then the irons are either junk or need to be nitrited again, in most cases lapping and nitriting cost about $150-200 per iron.
lapping is recommended because the nitrite layer is only about .015" thick.
.003 is not a specification so i assume he meant .030" which is well beyond the nitrite layer. if you need to take off .030 to get a it back within spec then the irons are either junk or need to be nitrited again, in most cases lapping and nitriting cost about $150-200 per iron.
Don't know anyone who will "NITRIDE" used plates.
gd
06-24-11, 04:37 PM
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i would also recommend lapping versus a surface grinding, because surface grinding is not an even cut and will take off more material from some areas than others varied from the original true flat origination surface.
lapping is recommended because the nitrite layer is only about .015" thick.
.003 is not a specification so i assume he meant .030" which is well beyond the nitrite layer. if you need to take off .030 to get a it back within spec then the irons are either junk or need to be nitrited again, in most cases lapping and nitriting cost about $150-200 per iron.
lapping is recommended because the nitrite layer is only about .015" thick.
.003 is not a specification so i assume he meant .030" which is well beyond the nitrite layer. if you need to take off .030 to get a it back within spec then the irons are either junk or need to be nitrited again, in most cases lapping and nitriting cost about $150-200 per iron.
Don't know anyone who will "NITRIDE" used plates.
gd
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