Difference between revisions of "Upgrade/RFFoil/WoodsMetal"
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| − | Wood's metal is an | + | Wood's metal is an alloy with a low melting point, about 60 degrees C. A lot of information on Woods metal can just be found on WikiPedia: |
http://en.wikipedia.org/wiki/Wood%27s_metal | http://en.wikipedia.org/wiki/Wood%27s_metal | ||
| − | Wood's contains cadmium and lead, and therefore is poisonous. However, there are a variety of alloys with similar low melting point | + | Wood's metal contains cadmium and lead, and therefore is poisonous. However, there are a variety of alloys with similar low melting point that do not contain cadmium. |
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A few things that I found so far (September 2014) | A few things that I found so far (September 2014) | ||
| − | * non-toxic are field's metal (62 C) and cerrolow 136 (58 | + | * non-toxic are field's metal (62 C) and cerrolow 136 (58 C) |
* cerrosafe (74 C) is said to be specifically suitable for machining: this is probably because on solidification is first shrinks a little and then slowly expands again. after 1 hour it has almost exactly the same size as in the molten state | * cerrosafe (74 C) is said to be specifically suitable for machining: this is probably because on solidification is first shrinks a little and then slowly expands again. after 1 hour it has almost exactly the same size as in the molten state | ||
* cerrobend (basically Wood's metal) expands on solidification by about a factor 1.006 | * cerrobend (basically Wood's metal) expands on solidification by about a factor 1.006 | ||
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http://www.rotometals.com/SearchResults.asp?Search=fields+metal | http://www.rotometals.com/SearchResults.asp?Search=fields+metal | ||
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| + | In the end we have ordered from Lowden Limited 1kg of Fields metal and 1 kg of Cerrolow 136. These are less toxic. | ||
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| + | == How to decide on what to use? == | ||
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| + | Cerrolow 136 (58 �C, 8.5 kg/l, 1.7kEuro/liter) is about half the price of Field's metal (62 �C, 7.88 kg/l, 3.4kEuro/liter). | ||
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| + | What do we need to look at to decide which one we use? | ||
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| + | * shrinkage expansion after solidification: Clow136 skrinks 2x10-4. For a thickness of 2mm, that is less than 1 micron, so probably irrelvant. For Field's metal, we don't know. | ||
| + | * expansion coefficient? Both should be very close to Al (22-23x10^-6/�C). | ||
| + | * melting temperature/conductivity? (how warm could foil become while machining?) | ||
| + | * fluidity: how easily does it flow? does it have sufficient capillary action to make a good film between foil and mold? | ||
| + | * Al affinity: does it stick well to the Al during milling in its solid phase? can we easily get it off again in its liquid phase? | ||
| + | * recoverability: stuff is rather expensive (count 5 liter for final box?). how well can we recover it? | ||
| + | * toxity: Field's metal does not contain lead and less bismuth | ||