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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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cast iron
can anyone tell me that what is fludity in cast iron???should it be
more or less in c.i?? |
#2
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cast iron
wrote in message ... can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Do you want a definition of "fluidity" or a figure for CI? More or less that *what*? Steel? Pure iron? Try Google: http://en.wikipedia.org/wiki/Cast_iron Specifically - what did your teacher ask for? -- Jeff R. |
#3
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cast iron
"Jeff R." wrote in message u... wrote in message ... can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Do you want a definition of "fluidity" or a figure for CI? More or less that *what*? Steel? Pure iron? Try Google: http://en.wikipedia.org/wiki/Cast_iron Specifically - what did your teacher ask for? -- Jeff R. This is the time of year for that, isn't it? Happens other times, but seems to be more often just before spring break. Or I'm seeing things. Mike |
#4
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cast iron
On Feb 24, 4:54 am, wrote:
can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Isn't being "cast" meaning it is solid? So, there is no fluidity. Must be trick question on a final exam! Paul |
#5
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cast iron
On Sun, 24 Feb 2008 13:03:20 -0800 (PST), "
wrote: On Feb 24, 4:54 am, wrote: can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Isn't being "cast" meaning it is solid? So, there is no fluidity. Must be trick question on a final exam! Paul Glass is solid, yet its considered a "slow liquid" Maybe why all those old lathes wont hold tolerance anymore. The cast iron has flowed a bit. G Gunner |
#6
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cast iron
"Gunner" wrote in message ... On Sun, 24 Feb 2008 13:03:20 -0800 (PST), " wrote: On Feb 24, 4:54 am, wrote: can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Isn't being "cast" meaning it is solid? So, there is no fluidity. Must be trick question on a final exam! Paul Glass is solid, yet its considered a "slow liquid" Maybe why all those old lathes wont hold tolerance anymore. The cast iron has flowed a bit. G Gunner I realize you're joking, but the creep properties of cast iron, combined with the structural design of a lathe, doesn't lend itself to significant distortions from "flow." Now, if the bed of a lathe is under stress from being poorly aligned over a period of years or decades, that might be different. -- Ed Huntress |
#7
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cast iron
"Ed Huntress" wrote in message ... "Gunner" wrote in message ... On Sun, 24 Feb 2008 13:03:20 -0800 (PST), " wrote: On Feb 24, 4:54 am, wrote: can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Isn't being "cast" meaning it is solid? So, there is no fluidity. Must be trick question on a final exam! Paul Glass is solid, yet its considered a "slow liquid" this is incorrect. glass is classified as an amorphous solid. http://en.wikipedia.org/wiki/Amorphous Maybe why all those old lathes wont hold tolerance anymore. The cast iron has flowed a bit. G Gunner regards, charlie http://glassartists.org/chaniarts |
#8
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cast iron
"charlie" wrote in message ... "Ed Huntress" wrote in message ... "Gunner" wrote in message ... On Sun, 24 Feb 2008 13:03:20 -0800 (PST), " wrote: On Feb 24, 4:54 am, wrote: can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Isn't being "cast" meaning it is solid? So, there is no fluidity. Must be trick question on a final exam! Paul Glass is solid, yet its considered a "slow liquid" this is incorrect. glass is classified as an amorphous solid. http://en.wikipedia.org/wiki/Amorphous Maybe why all those old lathes wont hold tolerance anymore. The cast iron has flowed a bit. G Gunner regards, charlie http://glassartists.org/chaniarts There's some truth in both statements, Charlie. Amorphous solids -- non-crystalline solids -- have no distinct melting point. The definition of the "glass-transition" temperature, which is arbitrarily considered the temperature at which an amorphous material passes from solid to liquid, is just a viscosity number grabbed out of thin air. So, to explain the behavior of glassy, or amorphous solids, teachers have often described glass, for example, as a "superliquid." The term has no precise meaning. It's just a handy description. There are some 250-year-old windows in one of my family's houses that make a strong case that glass is liquid. They look like wavy gravy at their bottoms, and it's not a result of being blown as cylinders and then cut and flattened (which is, of course, the way they were made). They all get wavy at the same point, on the bottom side. You could say that they're just especially subject to creep, if you think of them as solid. Or you could say they're just a very, very viscous liquid. -- Ed Huntress |
#9
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"Ed Huntress" wrote in message ... "charlie" wrote in message ... "Ed Huntress" wrote in message ... "Gunner" wrote in message ... On Sun, 24 Feb 2008 13:03:20 -0800 (PST), " wrote: On Feb 24, 4:54 am, wrote: can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Isn't being "cast" meaning it is solid? So, there is no fluidity. Must be trick question on a final exam! Paul Glass is solid, yet its considered a "slow liquid" this is incorrect. glass is classified as an amorphous solid. http://en.wikipedia.org/wiki/Amorphous Maybe why all those old lathes wont hold tolerance anymore. The cast iron has flowed a bit. G Gunner regards, charlie http://glassartists.org/chaniarts There's some truth in both statements, Charlie. Amorphous solids -- non-crystalline solids -- have no distinct melting point. The definition of the "glass-transition" temperature, which is arbitrarily considered the temperature at which an amorphous material passes from solid to liquid, is just a viscosity number grabbed out of thin air. did you read the link? it has nothing to do with the melting point. it has to do with the formation of crystals and the speed of cooling. So, to explain the behavior of glassy, or amorphous solids, teachers have often described glass, for example, as a "superliquid." The term has no precise meaning. It's just a handy description. they were wrong. There are some 250-year-old windows in one of my family's houses that make a strong case that glass is liquid. They look like wavy gravy at their bottoms, and it's not a result of being blown as cylinders and then cut and flattened (which is, of course, the way they were made). They all get wavy at the same point, on the bottom side. You could say that they're just especially subject to creep, if you think of them as solid. Or you could say they're just a very, very viscous liquid. -- Ed Huntress that is also incorrect. your wavy windows did not creep. that again is an old wive's tale. your windows were made that way because the craftsmen of the time thought they would last longer with the wavy or thicker part down, or did it because of esthetics in your case as it would look odd to have the demarkation lines at different points in adjacent windows. if this were true, then why aren't the glass objects the egyptians made 5000 years ago puddles in a museum about now? there are articles that measure the creep or thickening of glass, and the time for this to occur to something you could see is longer than the age of the earth. http://www.glasslinks.com/newsinfo/supercooled.htm http://math.ucr.edu/home/baez/physic...ass/glass.html "The use of the term "supercooled liquid" to describe glass still persists, but is considered by many to be an unfortunate misnomer that should be avoided. In any case, claims that glass panes in old windows have deformed due to glass flow have never been substantiated. Examples of Roman glassware and calculations based on measurements of glass visco-properties indicate that these claims cannot be true. The observed features are more easily explained as a result of the imperfect methods used to make glass window panes before the float glass process was invented." regards, charlie http://glassartists.org/chaniarts |
#10
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cast iron
"charlie" wrote in message ... "Ed Huntress" wrote in message ... "charlie" wrote in message ... "Ed Huntress" wrote in message ... "Gunner" wrote in message ... On Sun, 24 Feb 2008 13:03:20 -0800 (PST), " wrote: On Feb 24, 4:54 am, wrote: can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Isn't being "cast" meaning it is solid? So, there is no fluidity. Must be trick question on a final exam! Paul Glass is solid, yet its considered a "slow liquid" this is incorrect. glass is classified as an amorphous solid. http://en.wikipedia.org/wiki/Amorphous Maybe why all those old lathes wont hold tolerance anymore. The cast iron has flowed a bit. G Gunner regards, charlie http://glassartists.org/chaniarts There's some truth in both statements, Charlie. Amorphous solids -- non-crystalline solids -- have no distinct melting point. The definition of the "glass-transition" temperature, which is arbitrarily considered the temperature at which an amorphous material passes from solid to liquid, is just a viscosity number grabbed out of thin air. did you read the link? it has nothing to do with the melting point. it has to do with the formation of crystals and the speed of cooling. I didn't read the link before writing, but I have now. It isn't very helpful. However, the description of glass from the same source says this: "Glass is generally treated as an amorphous solid rather than a liquid, though both views can be justified." It points to a rather detailed university reference, titled "Is Glass Liquid or Solid?", which concludes: "There is no clear answer to the question "Is glass solid or liquid?". In terms of molecular dynamics and thermodynamics it is possible to justify various different views that it is a highly viscous liquid, an amorphous solid, or simply that glass is another state of matter which is neither liquid nor solid. The difference is semantic." I don't want to get into a ****ing contest over this, but I've written entire articles about amorphous solids, including both glassy ceramics and glassy metals, and including the thermodynamic and metastable/kinetic properties of glass ceramics. If a material is amorphous, it doesn't form crystals -- that's the definition of "amorphous." But glass, and other glassy materials, can form crystals under specific conditions. So the shorthand of calling it a "slow liquid" or a "superliquid" isn't complete, but it isn't completely wrong, either. As I said, it's a handy description. If you want to get into the distinctive properties of amorphous solids with school students you're in for a very dissappointing time. It's actually quite a complex subject, one that's still evolving. So, to explain the behavior of glassy, or amorphous solids, teachers have often described glass, for example, as a "superliquid." The term has no precise meaning. It's just a handy description. they were wrong. As I said, it's a handy description. And if you're going to get into the expansion and exothermic properties of glass at the supposed "glass transition temperature," note that even water has a non-linear expansion property at a critical temperature above crystallization that isn't much different, physically, from the secondary "transformation" properties of glass. There are some 250-year-old windows in one of my family's houses that make a strong case that glass is liquid. They look like wavy gravy at their bottoms, and it's not a result of being blown as cylinders and then cut and flattened (which is, of course, the way they were made). They all get wavy at the same point, on the bottom side. You could say that they're just especially subject to creep, if you think of them as solid. Or you could say they're just a very, very viscous liquid. -- Ed Huntress that is also incorrect. your wavy windows did not creep. that again is an old wive's tale. your windows were made that way because the craftsmen of the time thought they would last longer with the wavy or thicker part down, or did it because of esthetics in your case as it would look odd to have the demarkation lines at different points in adjacent windows. OK. I've been corrected about that before but I keep forgetting. Old wives's tales die hard. d8-). Then, my glass-topped dining room table, which had a hefty planter on it for years and creeped so much that you can see it with the naked eye. if this were true, then why aren't the glass objects the egyptians made 5000 years ago puddles in a museum about now? Because they aren't stressed sufficiently to creep, for the viscosity of the glass. All glass creeps under load and time. So does steel. So does concrete. What you're saying is that the stress level for glass to creep in human-scale quantities of time is higher than the load imposed by the glass's own weight. That's true of most materials. there are articles that measure the creep or thickening of glass, and the time for this to occur to something you could see is longer than the age of the earth. http://www.glasslinks.com/newsinfo/supercooled.htm http://math.ucr.edu/home/baez/physic...ass/glass.html "The use of the term "supercooled liquid" to describe glass still persists, but is considered by many to be an unfortunate misnomer that should be avoided. In any case, claims that glass panes in old windows have deformed due to glass flow have never been substantiated. Examples of Roman glassware and calculations based on measurements of glass visco-properties indicate that these claims cannot be true. The observed features are more easily explained as a result of the imperfect methods used to make glass window panes before the float glass process was invented." OK. But glassy solids, or amorphous solids, are still just very viscous liquids with close-order organization that gives them properties different from a standard liquid. Like Silly Putty, they can shatter, for example. But physics today describes supercooled liquids as something different. The physics of amorphous materials is not simple. Gunner's shorthand description is arguable as a partial explanation. "Amorphous solid," in thermodynamic terms, is an oxymoron. The implications of calling glass a "liquid" can be misleading if it's carried too far, to be sure. But so are most simplifications. That includes calling glass a "solid." -- Ed Huntress |
#11
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cast iron
On Tue, 26 Feb 2008 09:51:28 -0700, "charlie"
wrote: "Ed Huntress" wrote in message ... "Gunner" wrote in message ... On Sun, 24 Feb 2008 13:03:20 -0800 (PST), " wrote: On Feb 24, 4:54 am, wrote: can anyone tell me that what is fludity in cast iron???should it be more or less in c.i?? Isn't being "cast" meaning it is solid? So, there is no fluidity. Must be trick question on a final exam! Paul Glass is solid, yet its considered a "slow liquid" this is incorrect. glass is classified as an amorphous solid. http://en.wikipedia.org/wiki/Amorphous Wiki seemed to have missed this... http://www.sciencedaily.com/releases...0809130014.htm Maybe why all those old lathes wont hold tolerance anymore. The cast iron has flowed a bit. G And you seemed to have missed the G Gunner regards, charlie http://glassartists.org/chaniarts |
#12
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cast iron
On 26 Feb 2008 12:49:59 -0500, Maxwell Lol wrote:
Gunner writes: Glass is solid, yet its considered a "slow liquid" Urban myth. http://en.wikipedia.org/wiki/Glass#B..._antique_glass You also seemed to have missed the G Tuesdays are Humor Impaired days? Gunner |
#13
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cast iron
charlie wrote:
Glass is solid, yet its considered a "slow liquid" Gunner this is incorrect. glass is classified as an amorphous solid. http://en.wikipedia.org/wiki/Amorphous regards, charlie You know thats the trouble with science, they keep changing things. When I was in school (which was even farther back than when Gunner was) I'm pretty sure it was considered a "super cooled liquid" or some such description. :-) ...lew... |
#14
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cast iron
"Lew Hartswick" wrote in message ... charlie wrote: Glass is solid, yet its considered a "slow liquid" Gunner this is incorrect. glass is classified as an amorphous solid. http://en.wikipedia.org/wiki/Amorphous regards, charlie You know thats the trouble with science, they keep changing things. When I was in school (which was even farther back than when Gunner was) I'm pretty sure it was considered a "super cooled liquid" or some such description. :-) ...lew... That was before global warming. Now they realize it's not really supercooled. ga -- Ed Huntress |
#15
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cast iron
Ed Huntress wrote:
But glass, and other glassy materials, can form crystals under specific conditions. Inquiring minds and all- How does one make a glass crystal without introducing impurities (and making it simply glass like)? Kevin Gallimore |
#16
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cast iron
"axolotl" wrote in message ... Ed Huntress wrote: But glass, and other glassy materials, can form crystals under specific conditions. Inquiring minds and all- How does one make a glass crystal without introducing impurities (and making it simply glass like)? Kevin Gallimore 'Can't help there, Kevin. Quartz is, of course, chemically identical to glass, but is crystalline. And practically all glasses contain impurities. -- Ed Huntress |
#17
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cast iron
On Feb 26, 3:56*pm, "Ed Huntress"
'Can't help there, Kevin. Quartz is, of course, chemically identical to glass, but is crystalline. And practically all glasses contain impurities. -- Ed Huntress Actually quartz can be either crystalline or amorphous. Dan |
#18
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cast iron
wrote in message ... On Feb 26, 3:56 pm, "Ed Huntress" 'Can't help there, Kevin. Quartz is, of course, chemically identical to glass, but is crystalline. And practically all glasses contain impurities. -- Ed Huntress Actually quartz can be either crystalline or amorphous. Dan Clear, pink, and other colors, too. g -- Ed Huntress |
#19
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cast iron
Ed Huntress wrote:
"axolotl" wrote in message ... Ed Huntress wrote: But glass, and other glassy materials, can form crystals under specific conditions. Inquiring minds and all- How does one make a glass crystal without introducing impurities (and making it simply glass like)? Kevin Gallimore 'Can't help there, Kevin. Quartz is, of course, chemically identical to glass, but is crystalline. And practically all glasses contain impurities. That's a bit like someone I saw calling inconel stainless steel. While common glasses are predominately SiO2 it does have significant additions of other chemicals to give it the required properties and to lower the working temperature to something acceptable. Citing wiki http://en.wikipedia.org/wiki/Glass for some info, although I think it is wrong with the melting point for SiO2 which is normally given as 1650C. I do some glassblowing as a hobby and the glass is normally gathered at about 1050C(1922F) to 1100C(2012F) depending on the glass type, the lead glass being 24% PbO, by weight I think. The glass used for manual glassblowing being formulated to give a long working period, whereas machine made glass typically stiffens much more quickly to suit rapid turnaround. A very different material to quartz. -- Ed Huntress |
#20
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cast iron
"David Billington" wrote in message ... Ed Huntress wrote: "axolotl" wrote in message ... Ed Huntress wrote: But glass, and other glassy materials, can form crystals under specific conditions. Inquiring minds and all- How does one make a glass crystal without introducing impurities (and making it simply glass like)? Kevin Gallimore 'Can't help there, Kevin. Quartz is, of course, chemically identical to glass, but is crystalline. And practically all glasses contain impurities. That's a bit like someone I saw calling inconel stainless steel. While common glasses are predominately SiO2 it does have significant additions of other chemicals to give it the required properties and to lower the working temperature to something acceptable. Citing wiki http://en.wikipedia.org/wiki/Glass for some info, although I think it is wrong with the melting point for SiO2 which is normally given as 1650C. I do some glassblowing as a hobby and the glass is normally gathered at about 1050C(1922F) to 1100C(2012F) depending on the glass type, the lead glass being 24% PbO, by weight I think. The glass used for manual glassblowing being formulated to give a long working period, whereas machine made glass typically stiffens much more quickly to suit rapid turnaround. A very different material to quartz. That's certainly true. Except when it's not. g Unlike Inconel, glass is not a specific alloy. And there certainly are glasses that are pure or nearly pure silica: fused quartz glass, and fused silica glass, for example. These are technical glasses that you aren't likely to encounter in your glassblowing hobby, but they're chemically identical to crystalline quartz. The term "glass" itself is pretty flexible, as you know. And Kevin's question about pure silica glass does have some answers. There are products made from pure quartz, as well as synthetic ones that wind up being pure silica in the final product. Concerning melting temperatures, I'm not familiar with the actual numbers, but watch for confusion to arise over the definition of "melting temperature" for glass. As I said earlier, it's defined arbitrarily on the basis of a selected value of viscosity. It may not have much to do with the working properties with which you're familiar. -- Ed Huntress |
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