A question for those who know about casting techniques....

Was watching this the other day:

http://www.youtube.com/user/lieniels...e=results_main

(kind of explains the price they charge for their planes etc!)

During the section in the foundry, after decanting molten metal into the
first intermediate container, you see a chap throw a block of something
into the mix which results in lots of "activity" and bright white light
production from it? What is all that about?

Also at various stages they also seem to chuck tubs of a power or
similar in...



--
Cheers,

John.

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John Rumm wrote:

A question for those who know about casting techniques....
Was watching this the other day:

http://www.youtube.com/user/lieniels...e=results_main

During the section in the foundry, after decanting molten metal into the
first intermediate container, you see a chap throw a block of something
into the mix which results in lots of "activity" and bright white light
production from it? What is all that about?

I had 16 years in different foundries until they (nearly) all shut down.

It's a magnesium compound to change the plain cast iron into spheroidal
graphite (SG) iron. The way they do it in the video is a bit old
fashioned, we've been doing it during the pouring of the metal here for
30+ years ( I think it was a patented method when first brought in).
It makes the cast iron far more ductile, with up to 25% tensile stretch
before it breaks.
Chucking in on top of the ladle does not always distribute the magnesium
evenly.

Also at various stages they also seem to chuck tubs of a power or
similar in...

Rice crispies, (or snap crackle and pop). Sounds just like it when you
throw it on. The slag (impurities) are molten on the surface of the
iron, you sprinkle this powder on, and it coagulates the slag, and
sometimes sets it into an easy to remove lump.
The extra flashing is the magnesium being mixed in that was floating on
the surface.

Alan.
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"John Rumm" wrote in message
o.uk...
A question for those who know about casting techniques....

Was watching this the other day:

http://www.youtube.com/user/lieniels...e=results_main

(kind of explains the price they charge for their planes etc!)

I didn't realise they used such crude techniques as sand casting.

For the price they charged I would have thought they used forged steel
blanks and machined all the surfaces.



During the section in the foundry, after decanting molten metal into the
first intermediate container, you see a chap throw a block of something
into the mix which results in lots of "activity" and bright white light
production from it? What is all that about?

Also at various stages they also seem to chuck tubs of a power or similar
in...



Flux and other stuff they want in the alloy.


I bet they could take a block of steel or tungsten and CNC it into a better
plane than the way they make them in that video.

A.Lee wrote:

John Rumm wrote:

A question for those who know about casting techniques....
Was watching this the other day:

http://www.youtube.com/user/lieniels...e=results_main

I daren't look at the price of the finished plane.

you see a chap throw a block of something
into the mix which results in lots of "activity" and bright white light

It's a magnesium compound to change the plain cast iron into spheroidal
graphite (SG) iron.

From the light I thought it might be magnesium!

http://www.ductile.org/didata/Section2/2intro.htm#History%20of%20Ductile%20Iron%20Develop ment

On Mon, 18 Jun 2012 08:03:13 +0100, dennis@home wrote:

For the price they charged I would have thought they used forged steel
blanks and machined all the surfaces.

Wouldn't a forged and machined blank have stabilty problems due to
uneven stresses in the metal?

--
Cheers
Dave.

On 18/06/2012 08:03, dennis@home wrote:


"John Rumm" wrote in message
o.uk...
A question for those who know about casting techniques....

Was watching this the other day:

http://www.youtube.com/user/lieniels...e=results_main

(kind of explains the price they charge for their planes etc!)

I didn't realise they used such crude techniques as sand casting.

It is an excellent way to make complex shapes.

For the price they charged I would have thought they used forged steel
blanks and machined all the surfaces.



During the section in the foundry, after decanting molten metal into
the first intermediate container, you see a chap throw a block of
something into the mix which results in lots of "activity" and bright
white light production from it? What is all that about?

Also at various stages they also seem to chuck tubs of a power or
similar in...



Flux and other stuff they want in the alloy.


I bet they could take a block of steel or tungsten and CNC it into a
better plane than the way they make them in that video.

It is a foundry. Why would they want to make it any other way? In any
case, machining it would produce a lot of scrap, which casting does not.

Colin Bignell

"Dave Liquorice" wrote in message
ll.co.uk...
On Mon, 18 Jun 2012 08:03:13 +0100, dennis@home wrote:

For the price they charged I would have thought they used forged steel
blanks and machined all the surfaces.

Wouldn't a forged and machined blank have stabilty problems due to
uneven stresses in the metal?

That would be why they use forging to make critical components and casting
to make cheap stuff in industry then?

On Mon, 18 Jun 2012 03:29:52 +0100, John Rumm
wrote:

Was watching this the other day:

http://www.youtube.com/user/lieniels...e=results_main

(kind of explains the price they charge for their planes etc!)

During the section in the foundry, after decanting molten metal into the
first intermediate container, you see a chap throw a block of something
into the mix which results in lots of "activity" and bright white light
production from it? What is all that about?

Afair, it's a lump of calcium carbonate, which forms a slage on the
top, which you see the bloke raking off.
Used to see them doing that down the steelworks every day.

On 18/06/2012 04:56, A.Lee wrote:
John wrote:

A question for those who know about casting techniques....
Was watching this the other day:

http://www.youtube.com/user/lieniels...e=results_main

During the section in the foundry, after decanting molten metal into the
first intermediate container, you see a chap throw a block of something
into the mix which results in lots of "activity" and bright white light
production from it? What is all that about?

I had 16 years in different foundries until they (nearly) all shut down.

It's a magnesium compound to change the plain cast iron into spheroidal
graphite (SG) iron. The way they do it in the video is a bit old
fashioned, we've been doing it during the pouring of the metal here for
30+ years ( I think it was a patented method when first brought in).
It makes the cast iron far more ductile, with up to 25% tensile stretch
before it breaks.
Chucking in on top of the ladle does not always distribute the magnesium
evenly.

How would it normally be done here?

Also at various stages they also seem to chuck tubs of a power or
similar in...

Rice crispies, (or snap crackle and pop). Sounds just like it when you
throw it on. The slag (impurities) are molten on the surface of the
iron, you sprinkle this powder on, and it coagulates the slag, and
sometimes sets it into an easy to remove lump.
The extra flashing is the magnesium being mixed in that was floating on
the surface.

Thanks for that clear explanation ;-)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

On 18/06/2012 04:56, A.Lee wrote:
John wrote:

A question for those who know about casting techniques....
Was watching this the other day:

http://www.youtube.com/user/lieniels...e=results_main

During the section in the foundry, after decanting molten metal into the
first intermediate container, you see a chap throw a block of something
into the mix which results in lots of "activity" and bright white light
production from it? What is all that about?

I had 16 years in different foundries until they (nearly) all shut down.

It's a magnesium compound to change the plain cast iron into spheroidal
graphite (SG) iron. The way they do it in the video is a bit old
fashioned, we've been doing it during the pouring of the metal here for
30+ years ( I think it was a patented method when first brought in).
It makes the cast iron far more ductile, with up to 25% tensile stretch
before it breaks.
Chucking in on top of the ladle does not always distribute the magnesium
evenly.

How would it normally be done here?

Depends on who is doing it.
One place I worked, there would be an intermediate spout, a bit like an
elongated, flat, funnel. Before the metal was needed, 20kg or so of
magnesium mix was put inside the funnel (for 500kg of cast metal), then
the metal poured from the furnace, through the funnel, and into the
pouring ladle.
It mixed as it went through, and was pretty much fool proof, as it would
be mixed again as it churned about when entering the large ladle,
ensuring all of the metal had its influx of magnesium.

You'd then put the collagulant on, scrape off the slag and impurites,
then pour it when the temperature was right.

You had a limited time to do it, 5 minutes or less, as the magnesium
burned off. With full treatment, all of the carbon in the metal would be
in spheroidal shapes. As it went off, the carbon would gradually return
to its natural state in cast iron, looking like corn flakes when viewed
through a microscope - this is why grey cast iron is brittle - it snaps
along the lines of graphite. SG does away with this weakness, adds
tensile strength, but loses some hardness, but is far cheaper than steel
to produce.
Each pouring had to have a sample taken, and polished and viewed through
the microscope. Something like less than 75% spheroidal would result in
all of that batch being quarantined, possibly scrapped if the castings
were no better than the sample.

Another place did it with the magnesium in the mould, in a little
chamber, which swirled the metal round as it was poured in. This got
away with the problem of the magnesium buring off, but there was the
added problem of impurities in the finished casting due to the swirling
and splashing inside the mould, which could be negated slightly by
designing some curves and stops on the runnings bars (where the molten
metal runs to get to the finished piece mould).



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On Monday, June 18, 2012 3:49:34 PM UTC+1, A.Lee wrote:

Depends on who is doing it.
One place I worked, there would be an intermediate spout, a bit like an
elongated, flat, funnel. Before the metal was needed, 20kg or so of
magnesium mix was put inside the funnel (for 500kg of cast metal), then

Thanks for that Mr. Lee, I'd always wondered how they made grey cast iron into the SG stuff but had never tried to find out.

Presumably, a few of the eye-wateringly expensive planes might shatter if dropped?

A lot of the cast iron stuff you see sold in the UK (wood burning stoves, typically) is obviously
made in some Asian sweat shop foundry. I believe that most of it is grey cast iron but don't know for certain.
Would you expect it to be the grey, brittle variety? Is the magnesium additive stuff very expensive?

Onetap wrote:

A lot of the cast iron stuff you see sold in the UK (wood burning
stoves, typically) is obviously made in some Asian sweat shop foundry. I
believe that most of it is grey cast iron but don't know for certain.
Would you expect it to be the grey, brittle variety?

Yes, I would guess that most of the cast iron stoves, garden seat ends
etc would be grey cast iron.
Anything with a precision use (in the loosest terms), such as exhaust
manifolds, pump bodies etc would be of one of the ductile alloys, making
them easier to machine, and harder to break.

Is the magnesium additive stuff very expensive?

For cheap consumer goods with little problem if they do break, then yes
it would be expensive. The expense would be mainly in the quality
control of the metal - it doesnt work with too high carbon, sulphur,
silicon, manganese and other elements in it. To get a good alloy, you
need to use a good starting point, roughly 50% good quality steel
scrap, and 50% old iron castings to give a good alloy.

For cheap castings, they would be likely to melt down anything that came
in, giving an alloy that would not be suitable for any ductile
treatment, but fine for big lumps that are not likely to be machined or
bashed in use.

Alan.
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On Sunday, June 24, 2012 9:02:08 AM UTC+1, A.Lee wrote:

Yes, I would guess that most of the cast iron stoves, garden seat ends
etc would be grey cast iron.

Thank you, much appreciated.

On 24/06/2012 09:02, A.Lee wrote:
Onetap wrote:

A lot of the cast iron stuff you see sold in the UK (wood burning
stoves, typically) is obviously made in some Asian sweat shop foundry. I
believe that most of it is grey cast iron but don't know for certain.
Would you expect it to be the grey, brittle variety?

Yes, I would guess that most of the cast iron stoves, garden seat ends
etc would be grey cast iron.
Anything with a precision use (in the loosest terms), such as exhaust
manifolds, pump bodies etc would be of one of the ductile alloys, making
them easier to machine, and harder to break.

Is the magnesium additive stuff very expensive?

For cheap consumer goods with little problem if they do break, then yes
it would be expensive. The expense would be mainly in the quality
control of the metal - it doesnt work with too high carbon, sulphur,
silicon, manganese and other elements in it. To get a good alloy, you
need to use a good starting point, roughly 50% good quality steel
scrap, and 50% old iron castings to give a good alloy.

Does not the inclusion of scrap steel in effect mean the new alloy is
also a form of steel rather than iron in the strict sense? Or is it a
percentage thing when it comes to classification?


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

On 24/06/2012 09:02, A.Lee wrote:

For cheap consumer goods with little problem if they do break, then yes
it would be expensive. The expense would be mainly in the quality
control of the metal - it doesnt work with too high carbon, sulphur,
silicon, manganese and other elements in it. To get a good alloy, you
need to use a good starting point, roughly 50% good quality steel
scrap, and 50% old iron castings to give a good alloy.

Does not the inclusion of scrap steel in effect mean the new alloy is
also a form of steel rather than iron in the strict sense? Or is it a
percentage thing when it comes to classification?

Percentage.
Steel has a low carbon content, up to 1%, cast iron can go up to 5%.
Other elements come into it as well, so it is very rare to be able to
melt down old iron castings, and use it again, you usually have to add
some things, and take away silicon and other elements.

Ductile irons need a balanced amount of each element, say 0.6% copper,
2.7% carbon, 1% silicon etc. Melting down old scrap cannot give this, so
a mix of good quality steel (with its high iron content, and low other
elements) dilutes the mixture, allowing you to adjust the alloy to get
the result you want.
You could add carbon, manganese and copper and other elements if needed.

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On 24 Jun,
(A.Lee) wrote:

Percentage.
Steel has a low carbon content, up to 1%, cast iron can go up to 5%.
Other elements come into it as well, so it is very rare to be able to
melt down old iron castings, and use it again, you usually have to add
some things, and take away silicon and other elements.

Ductile irons need a balanced amount of each element, say 0.6% copper,
2.7% carbon, 1% silicon etc. Melting down old scrap cannot give this, so
a mix of good quality steel (with its high iron content, and low other
elements) dilutes the mixture, allowing you to adjust the alloy to get
the result you want.
You could add carbon, manganese and copper and other elements if needed.

When I visited Hepworth and Grandage???'s foundry about 40 years ago they
used a mix of scrap in their electric furnace. they then blew oxygen through
it and then sent a sample to the labs whilst th melt was on hold. When the
results were returned they then threw in selected scrap and other additives
to make the carbon (and other alloying elements) up to the required amount.

Presumably experience determined the mix of washing machines, old engine
blocks, tin cans, girders, irn bru etc. used in the original mix.

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On Mon, 25 Jun 2012 00:55:58 +0100, wrote:

When I visited Hepworth and Grandage???'s foundry about 40 years ago they
used a mix of scrap in their electric furnace. they then blew oxygen through
it and then sent a sample to the labs whilst th melt was on hold. When the
results were returned they then threw in selected scrap and other additives
to make the carbon (and other alloying elements) up to the required amount.

Presumably experience determined the mix of washing machines, old engine
blocks, tin cans, girders, irn bru etc. used in the original mix.

Exactly the same process on a larger scale took place in the
steelworks where I worked almost exactly 40 years ago on leaving
school. Fascinating stuff, at the time.
It occurred to me what a splendid way of getting rid of evidence it
was.