Pearlitic cast iron

[PeterB]

My next project is Jan Ridders 1-cyl Flame Eater with internal valve.
The internal valve and piston should be made of "pearlitic cast iron". But I can not find a shop where I can buy it.

Now the question: Can I use automatic steel instead of pearlitic cast iron?

 

[Bastelmike]

Hello PeterB,

my first question is, does Jan specify pearlitic cast iron, or does he want ductile iron - cast iron with globular graphite ?
I know of sources for ductile iron off the shelf in round or square; but I dunno any source for something special like pearlitic iron.
How about a short mail to Jan Ridders?

As for the piston, I am not sure whether steel would be a good choice. Cast iron has better properties for sliding parts because of the graphite parts it contains, they are a lubricant for the piston.
Which material is the sliding counterpart, sleeve or cylinder?

For the valve, for me its a question of temperature. For lower temperature every steel should do the job.

Mike

 

[Cogsy]

The internal valve and piston should be made of "pearlitic cast iron

Are you sure you have the latest up-to-date plans for this engine? I've just built it and the plans I got from Jan use graphite for both the piston and valve. Also, Jan suggests Stainless steel for the cylinder although the plans say Aluminium. I built mine using Aluminium but I think the stainless would have been a better material to use.

Good luck with the build. I'm looking forward to seeing it come to life.

 

[lensman57]

Hi,

I build mine out of CI as sugggested by Jan in his original plans. He may have revised his plans and suggested new materials. The choice of cast iron was beacause of :
A: CI retains heat almost better than any other material, this is necessary for the smooth operation of the vaccum engines.
B: CI is a self lubricating material therefore the combination of CI cylinder and piston dies not require any lubricants whose residue will impair the operation of the engine.
On the negative side CI rusts like hell due to the high water vapour present in the combustion of the alchohol, this is not desirable as you are not to lubricate the piston and the cylinder to avoid rust.
The change in material from CI to Stainless and Gaphite will, to a great extent retain the positive qualities of the CI and aviods the negatives as the Graphite piston is almost frictionless. The question however remains, as to what type of Graphite Jan has specified.
If you are living in the UK, it would be very difficult to find any type of Graphite let alone specific grade of this as I have found out.
Perhaps you could email Jan and ask him, he seems to be a very helpful chap.

Regards,

A.G

 

[PeterB]

Hmm... I searched on internet what kind of material Pearlitic Cast Iron is and now I know. I found an explanation in swedish that helped me a lot.
http://sv.wikipedia.org/wiki/Gjutjärn

English version here.

Cast Iron = Gjutjärn

And what I could see, there is four different types of it.
Gråjärn, Segjärn, Vitjärn and Aducerjärn.

And I have a little bit of Cast Iron on my table so I can go forward with my little Flame Eater.

I have made the Mounting base and the cylinder support. Next thing to do is the cylinder.

 

[Cogsy]

He may have revised his plans and suggested new materials.

I haven't seen the old plans, but I believe there are significant changes to bores sizes (up from 18mm to 22mm I think) and some changes to make construction easier, as well as the material differences.

Still, the old design worked as far as I know, so it's no big deal.

 

[PeterB]

The plan I've got is dated Dec-14-2005 and Update Aug-30-2008. The cylinders bore size is 18 mm.
Jan doesn't send it to me. I've found the PDF on the net. I don't remember the URL but the plan was free with Jans permission.

 

[Bastelmike]

Hi Peter,

I looked into two books now and try to explain now a bit about the different types of cast iron. Sorry I can only use european standard designations.

Basically there are two types: iron with lamilar graphite parts GJL and with spheroidal graphite GJS, thats in english called ductile iron.
Besides these main types there are several special varieties like austenitic iron ....

Both GJL and GJS contain ferritic and pearlitic types:

GJL-150 ferritic (older german name GG-15)
GJL-200 ferritic-pearlitic
GJL-250 and higher pearlitic

GJS-400 and GJS-500 ferritic (older german name GGG-40, GGG-50)
GJS-600 and higher pearlitic

Maybe this helps a bit in understanding which cast iron is pearlitic.

Mike

 

[Cogsy]

The plan I've got is dated Dec-14-2005 and Update Aug-30-2008. The cylinders bore size is 18 mm.
Jan doesn't send it to me. I've found the PDF on the net. I don't remember the URL but the plan was free with Jans permission.

That is an older plan, the latest is March 17 2011.

Jan's site has lots of info to help with the build and troubleshoot the engine and is definitely worth a look. It loads in Dutch but has a couple buttons at the top to change both the text and menu to English. If you want the latest plan, an email to Jan normally gets a very quick response.

The link is : http://heetgasmodelbouw.ridders.nu/Webpaginas/pagina_happer_inw_schuif/inw_schuif_frameset.htm

 

[Entropy455]

http://www.allmetalssupply.com/cast_iron.htm

Pearlite is a lamellar structure of the metal’s grain boundaries. Said another way, pearlite describes the behavior of how alpha-ferrite (88% by weight) and cementite (12% by weight) forms during the heat-treating process. Perlite production is maximized when the cast iron is heated and fully dissolved as austenite, then slow-cooled over many hours. This is the opposite of forming martensite, which is a very hard lattice structure that’s formed by rapidly cooling austenite. Needless to say, martensite is not easy to machine.

Do remember when you’re shopping, that both grey iron and ductile iron (aka nodular iron) are both heat treatable alloys. Normally when you purchase either material in its raw state, it will be fully annealed.Thus its pearlite concentration will be maximized, and the material will be in its easiest-to-machine state.

If you desire to avoid heat treating the part after machining,you'll most likely want to use grey cast iron. Grey cast iron is strong, wear resistant, and known for its ability to dampen vibrations. Key word is wear resistant.

Ductile Iron (aka nodular iron) is stronger than grey cast iron. It has a greater impact resistance, which is why it’s often used to make crankshafts and gears. However to get good wear resistance from ductile iron,you MUST case harden it.

I linked a place to purchase cast iron. Note: I’ve never purchased from these guys before, and I have no idea as to the quality of their product, or the reasonableness of their prices. . . . It does look like however that they offer medium-hard cast iron. This will be harder to machine, but your parts will hold up much better in wear resistance.

 

[lensman57]

Hi,

I beleive that if you were to stay with cast iron, a grey cast iron would be suitable as these are the easiest to machine and are the mostly available of the lot from model engineering suppliers, at least here in the UK. The mostly available grade is GR17 British Standard or grade 250 to the rest of the world, preferable if it is a Meehanite production.The other grade of CI which is available is SG(GGG40). This stands for Spheroidal Graphite or the Ductile CI. These are mainly used for high stress applications such as crankshafts or similar. So as long as you obtain grey CI you are set to go. I am interested to see the new plans as my engine was constructed from the very first set of plans that were available and it was neither easy to build nor to get going, particularly as it was my second attempt at engine building. As difficult as it was I wonder how the good folks in the forum feel about drilling and boring stainless steel to the dimensions mentioned. The problem of the availabilty of Graphite not withstanding, of course. Hope this helps.

Regards,

A.G

 

[PeterB]

I 've send a mail to Jan. I hope he will send me the new plan. I also asked abot the material in piston and cylinder. I will tell you more when he send me an answer.

 

[gus]

Hi Entropy,

Thanks for the enlightment.Most of us retirees have forgotten metallurgy cramped into our brainbox many years ago.
Pearlites,ferrites,austenites,martensites etc took a long time to remember when we were in trade school and technical college.