STRESS RELEAVING/ STABILIZING CAST IRON

[pete]

In an earlier post I mentioned that I had a full set of unmachined castings and drawings for a Sanderson Beam Engine in 1/12th scale obtained from Great Britten 10-12 yrs. ago, One of my relatives and I want to build two of these engines but blown up by 50% to 1/8th scale, ( He's pretty good with Auttocad and is reworking all the drawings to 1/8th).

We could make patterns and then have castings poured but would prefer not to do so, What we want to do is machine all the parts from cast iron plate and rod stock.
Does anyone have any opionions on what grade/type of cast iron we should use?

As far as I know at one time cast iron engine blocks were rough machined then placed outside to go thru numerous heating, cooling cycles that took months to slowly stress releave these engine blocks and then they were re-machined to final correct dimentions. Can the same thing be done at home on a smaller scale? by useing the kitchen oven/freezer. If we rough cut the bar and plate material then place this in the oven at say 300-500 degrees F. then hold that temp for an hr. then cool slowly to room temp. then place the cast iron in the freezer for a couple of day's then repeat the heat/cool cycle 4-6 more times would this compleatly stress releave the material? These beam engines will not be cheap to build in materials and tooling so we do NOT want the parts to warp after machining, what is machined flat HAS to stay flat.With the ammount of talent and experience on this site someone has to know how to do this the easy way.

Pete

 

[compound driver 2]

Continuose cast mehanite is the best iron to use for a job like that. you dont need speroidal graphite its over the top.
You will NOt need to stress relieve Mehanite and its very consistant through out the bar.
Plate iron again Mehanite.

I am machining cylinder blocks for steam most weeks and its the only material il use.

 

[pete]

Compound: Thanks very much for the info, Were planning to sell c.d.s with plans and machining instructions for this beam engine once engines are completed and plans are proven correct, and we will credit you with provided information for material specs. Again thanks a lot.

Pete

 

[Richard Carlstedt]

If you buy normal cast iron plate and bar, you will not need to relieve it. Working with Castings is a totally different situation.
In a production operation, time is important and so the engine blocks were pulled out to soon from the mold. Additives today and procedures have eliminated that for Car engines
Today, modern methods produce iron is a very stable form.
Freezing is good, as metal moves anytime it exceeds a lower temperature than it saw earlier.For model work its unnecessary.
Cast irons are known by their tensile strength,
Gray iron is soft and is 20 K Psi
Ductile irons are stronger at 40 to 60 K PSI
Meehanite is very strong ($) and goes from 60 to 130K PSI

you should have good luck with Ductile bar and plate.
As mentioned earlier by another poster, they generally call this"Continuous Cast"
See Mc Master Carr

If you want to see what can be done with Cast iron, go to my website and look at the hypocycloidal Engine, mostly from Cast iron plate. No Castings were used and no stainless.Just mild steel and Cast iron.
The steam cylinder and pump bowls were made with 80 K Meehanite
The upper base that has the big bull gear is 20 K iron.
The gears, pillow block bearings, pump bodies and pump housing were made with ductile 40 K iron.
I love working with CI, it is neat stuff.

Rich
www.stationarysteam.com

 

[Maryak]

Rich,

Had a peep at your site

They are magnificent engines

Best Regards
Bob

 

[kf2qd]

Another way to stress relieve cast iron is to tumble it for a while. The bouncing and banging does wonders and speeds up the process. Also heating them up - 500-600 degress and letting them soak for a few hours and them slow cooling. Because of the small size of the parts you would be making a couple hours would probably do. if you could get some castings from an oil fired furnace you would probably like them better than castings from an electric furnace - it may be because the oil fired furnace rotates and mixes the iron (and mabe adds some carbon) while it is molten. I have worked with some smaller castings - as long as the chemistry was right stability was not an issue. Your castings are not going to be that complex so all the horror stories don't really apply. if they really know what they are doing, the biggest problem will be getting the castings clean enough (grinding, sandblasting, wire brushing) so that all the sand is out of the way for the machining.

 

[raym 11]

Richard;
What is a source for purchasing meehanite?

Ray M

 

[pete]

Thanks again for everyones responses, Also if anyone knows of a supplier of Meehanite preferably on the west coast, U.S. or Canada It would be very helpfull.

Pete

 

[jack404]

Meehanite in the US of A is CI2 ( Cast Iron Grade 2) online metals has CI2 offcuts listed

its a bit more than regular but can be recast over and over

i use it here often enough, and is better that others i've tryed

good luck with it all eh

cheers

jack

 

[gmac]

Pete;
if you locate a source let me know - your neighbour in Penticton, BC. :big:

These guys may be able to identify sources on this side of the border, they don't list Meehanite on their website but do handle iron. Ontario based but have facilities in Edmonton. The Edmonton office was a little slow responding to my e-mails but did get back with good info.

http://www.terranovasteel.ca/Lang_English/contact.html

Product list;

http://www.terranovasteel.ca/Downloads/8323_TSI_AB_LineCard_A.pdf

Garry

 

[pete]

jack404 and gmac Thanks a lot for the info, will check them out. GMAC, Penticton eh! cool, your almost a neibour. If you want to send me a pm, Not too many HSM types in the Okanogan area.

Pete

 

[Noggin]

UK grade number for mehanite quality is "250" if anyone is interested.

 

[Mainer]

I think plain gray iron would be quite good enough for a model. If you get the continuous-cast stuff it won't need stress relieving.

 

[Jasonb]

Some of those parts may be easier to make by fabrication rather than machining from the solid in which case Mild steel would be better suited as its easily silver soldered whereas CI can be a bit tricky.

Jason

 

[pete]

Jason, Thanks for the info on soldering cast as I didn't know that. Yeah some of the parts may be alot easier to make useing mild steel. Will have to give this some thought.

Pete

 

[Kermit]

Meehanite as defined by a manufacturer in India. (I think there is some misspelled words in there as well)

The special features that make MEEHANITE are based on the microstructure. It differs from all other unalloyed or lightly alloyed normal carbon steels and cast irons in that its microstructure does not contain any hard and brittle iron carbide, i.e, cementite. Thus the basic components of MEEHANITE are ferrite, retained austenute and nodular graphite.
Austempering quenches cast iron or carbon steel above the austenite transformation ranges in a medium with a high enough rate of heat transfer to prevent the transformation of high temperature formation products. The process is completed at a temperature that is too low for pearlite to form and too high for martensite to form. Austempering involves quenching austenite and holding it at a constant temperature (usually between 450° F and 800° F) above the martensite start temperature (Ms) until transformation to bainite is complete. Bainite has a very fine acircular or feathery structure and a dispersion of cementite (iron carbide) and ferrite (alpha iron). Bainite is tougher than quenched and tempered structures in certain steels at specific hardness levels. The martensite transformation is a diffusionless reaction that proceeds rapidly (at the speed of sound) as a shear wave through the material. The martensite transformation often results in distortion and cracking in conventionally quench and tempered parts.

Cast irons are a large group of ferrous alloys which solidify with a eutectic. They contain high amounts of iron, significant amounts of silicon (about 1-3%), and are considered to be ternary alloys (Fe-C-Si). Cast irons tend to be brittle depending on the particular alloy. They generally have low melting points, good fluidity, castability, wear resistance, and excellent mechanicability. Because of these benefits, cast irons are being included in an increasing number of engineering applications, including pipes, machines, and car parts. Cast irons are available in two colors: gray and white.

Gray cast irons contain a significant amount of silicon. When this silicon is alloyed with ferrite and carbon (approximately 2% of each), the iron carbide becomes unstable. The silicon causes the carbon to quickly pull out of the solution, resulting in graphite. Once the carbon is extracted, the solution becomes a matrix of relatively pure, soft iron. Weak bonding occurs between the plates of graphite and leads to high-energy growth in that direction. As a result of that growth, thin flakes are formed. The benefit of working with graphite is that it can improve wear resistance due to its high thermal conductivity. When compared to steel, however, gray cast irons have less strength and shock resistance.

White cast irons have a lower silicone content and faster cooling times. Unlike gray cast irons, the carbon in white cast irons expedites out of the melt as the metastable phase cementite. The eutectic mixture that emerges from the initial participation is large and cannot undergo participation hardening. Instead, this mixture increases the bulk hardness. White cast irons are too brittle to be used in more structural components but their hardness and abrasion resistance allow them to be used in wear surfaces such as slurry pumps, lifter bars, shell liners, grinding mills, and the balls and rings of coal pulverizers.

Another form of cast irons is known as “malleable iron”. Malleable iron starts outs as white cast iron and is then heated to approximately 900° C. At this temperature the graphite separates out slowly, allowing surface tension to form into spheroidal particles rather than flakes. The end result is more like mild steel but there is a size limit because the material is made from white cast irons. Malleable irons are ideal for castings, especially ducts. The castings that use these irons most often are electrical fittings, hand tools, pipe fittings, washers, brackets, fence fittings, power line hardware, machine parts, farm equipment, and mining hardware.

http://www.globalspec.com/FeaturedP...hite_Types_Ductliron_/47840/0?fromSpotlight=1

Go there to look around some more and get more info on meehanite.

Kermit

Edit: should anyone become interested - globalspec has a membership and provides udates and links to news releases for a wide range of manufacturing and production industries. JUST KNOW THIS. Along with the nice info; once they have your email address you WILL BE emailed by the sales teams of ANY link you click on. Very aggrevating for someone just wanting to look for information. MY SUGGESTION? create a new email account just for this purpose and let them have that. then you can click on links to your hearts content and never be bothered by the sales teams.

Just thought I should save someone else the trouble I encountered(TANSTAAFL)there ain't no such thing as a free lunch

 

[Kermit]

AND FURTHERMORE. ;D

An interesting blurb from a copyrighted book, courtesy of www.books.google.com


View attachment meehanite.pdf

 

[Richard Carlstedt]

Pete
I lost track of this thread and so never responded
i am sure you can find a source of Meehanite from the company
http://www.meehanitemetal.com/

It is a superb metal, dense and strong.
I got mine from a Ontario Canada distributor years ago.
When you cut it, it makes very fine chips and so you get good finishes.
I think a 60 T Ductile iron with work for you too
You can find that in Mc Master car in all forms
or from other metal supplliers.
Rich

 

[zeeprogrammer]

Rich,

I hadn't seen this thread before. Very interesting.
Took a gander at your link too.
I have to agree with Maryak
th_confused0052

Thanks.

 

[pete]

Richard, Thanks for the heads up on the mehanite supplier. I'll be checking them out.

Pete